Article pubs.acs.org/JAFC
Cytotoxic Activity of Dietary Lignan and Its Derivatives: Structure− Cytotoxic Activity Relationship of Dihydroguaiaretic Acid Tuti Wukirsari,† Hisashi Nishiwaki,† Kosuke Nishi,† Takuya Sugahara,†,‡ Koichi Akiyama,§ Taro Kishida,†,‡ and Satoshi Yamauchi*,†,‡ †
Faculty of Agriculture and §Integrated Center for Sciences, Tarumi Station, Ehime University, 3-5-7 Tarumi, Matsuyama, Ehime 790-8566, Japan ‡ South Ehime Fisheries Research Center, 1289-1 Funakoshi, Ainan, Ehime 798-4292, Japan S Supporting Information *
ABSTRACT: Cytotoxic activities of synthesized lignan derivatives were estimated by WST-8 reduction assay against HL-60 and HeLa cells to show the structure−activity relationship. The activities of some effective compounds were examined against Colon 26 and Vero cells. Dietary secoisolariciresinol (SECO, 1) and its metabolite, 9,9′-anhydrosecoisolariciresinol (2), did not show the cytotoxic activity. On the other hand, all stereoisomers of dihydroguaiaretic acid (DGA, 9,9′-dehydroxysecoisolariciresinol, 3−5) exhibited the activity (IC50: around 30 μM). The IC50 value of (8R,8′R)-9-butyl DGA derivative 13 was around 6 μM. This fact means that the hydrophobic group was advantageous for higher activity at 9- and 9′-positions. By the evaluation of the effect of 7and 7′-aryl group on the activity, we discovered the highest activity of (8R,8′R)-7-(3-hydroxy-4-methoxyphenyl)-7′-(2ethoxyphenyl) DGA derivative 47 showing around 1 μM of IC50 value, which is about 24-fold higher activity than that of natural (8R,8′R)-DGA. The derivative of dietary lignan showed the high cytotoxic activity. KEYWORDS: lignan, cytotoxic activity, secoisolariciresinol, dihydroguaiaretic acid
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INTRODUCTION Lignans are widely distributed in grains, vegetables, and fruits.1 Applications of dietary and medicinal lignan to the health and food industry, including inhibitory activity of cAMP by dibenzylbutyrolactone and furofuran lignans,2 inhibitor and antagonist of PAF by neoliganan kadsurenone and (+)-dihydroguaiaretic acid,2 biological activity as polyphenol by furofuran lignan,3 IgE-suppressive activity−structure relationship of (−)-matairesinol,4 immunomodulatroy effect of (−)-matairesinol,5 effect of secoisolariciresinol (1) on 3T3-L1 adipocytes,6 inhibition of the discolorlation of yellowtail dark muscle by (−)-matairesinol,7 and cytotoxic activity−structure relationship of morinol A8 have been reported. Dietary lignans have served as lead structures for new clinical candidates from natural products. On the other hand, the research on metabolism of plant lignans to many types of lignans and lignan derivatives are also continuing,9 suggesting that new lignan metabolites would be discovered in the future. This fact suggests that the effect of each lignan and its derivative on health should be clarified by structure−activity relationship research because safety of food is focused. In this study, cytotoxic activity of dietary secoisolariciresinol (1) and its reductive products, dihydroguaiaretic acid stereoisomers (3-5), were examined as a first stage. The effect of the stereochemistry was compared and discussed for the first time. The activity of 9,9′-anhydrosecoisolariciresinol (2), which is proposed as a metabolite compound from secoisolariciresinol,10 was also estimated. As a next stage, we designed the 9- and 9′drivatives 6−15 and the aromatic derivatives 16−59 to clarify the structure−cytotoxic activity relationship for the first time. © 2014 American Chemical Society
To achieve this project, the synthetic route to 9- and 9′derivatives 6−15 was also developed (Figure 1). The effect of the structure between the 8- and 8′-position of butane-type lignan on the cytotoxic activity11 and butane-type lignan as an apoptosis inducer12 have been reported. However, structure−activity relationships on 9- and 9′-positions and 7and 7′-aromatic rings have been unknown. Our purpose is to find out the most advantageous substituent for cytotoxic activity on each portion. The results could give information about the structure−activity relationship of dietary and metabolite lignans, which contribute to development of new clinical medicine based on dietary compounds.
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MATERIALS AND METHODS Chemicals. (−)-Secoisolariciresinol (SECO) (1),13 9,9′anhydrosecoisolariciresinol (2),14 and stereoisomers of dihydroguaiaretic acid (3−5)15,16 were synthesized by the previously described method. The derivatives 6−15 were synthesized by the new synthetic method shown in Scheme 1, and their procedures are described in Supporting Information. The derivatives 16−59 were synthesized by the previously described method15 with modification. NMR data of 16−18, 20−24, 26−30, and 32−43 agreed with those of the literature.17,18 The [α]D values of 20−22, 26−28, and 32−34 were opposite but equal amounts to the corresponding enantiomers in the literature.18 Optical rotation values were Received: Revised: Accepted: Published: 5305
March 2, 2014 May 13, 2014 May 19, 2014 May 19, 2014 dx.doi.org/10.1021/jf5010572 | J. Agric. Food Chem. 2014, 62, 5305−5315
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Figure 1. Butane-type lignans and their derivatives.
J = 9.5, 5.4 Hz), 3.30 (6H, s), 3.35 (2H, dd, J = 9.5, 5.4 Hz), 3.76 (6H, s), 5.58 (2H, s), 6.51 (2H, d, J = 1.9 Hz), 6.59 (2H, dd, J = 7.9, 1.9 Hz), 6.78 (2H, d, J = 7.9 Hz); 13C NMR (100 MHz, CDCl3) δ 35.1, 40.6, 55.7, 58.7, 72.7, 111.3, 113.9, 121.9, 132.9, 143.6, 146.4; MS (EI) m/z 390 (M+, 41), 358 (21), 189 (32), 137 (100); HRMS (EI) m/z calcd for C22H30O6 390.2043, found 390.2050. (8R,8′R)-4,4′-Dihydroxy-3,3′-dimethoxy-9a,9′a-dihomolignane-9a,9′a- dinitrile (8). Colorless oil; [α]D25 +40 (c 0.5, CHCl3); 1H NMR (400 MHz, CDCl3) δ 2.24 (2H, m), 2.36− 2.38 (4H, m), 2.57 (2H, dd, J = 14.0, 9.4 Hz), 2.98 (2H, dd, J = 14.0, 5.0 Hz), 3.88 (6H, s), 5.58 (2H, s), 6.64 (2H, d, J = 1.9 Hz), 6.66 (2H, dd, J = 7.9, 1.9 Hz), 6.87 (2H, d, J = 7.9 Hz); 13 C NMR (100 MHz, CDCl3) δ 19.0, 36.3, 39.3, 56.0, 111.0, 114.7, 118.1, 121.7, 129.6, 144.7, 146.9; EIMS m/z 380 (M+, 43), 137 (100), 122 (12); HRMS (EI) m/z calcd for C22H24O4N2 380.1737, found 380.1739. (8R,8′R)-3,3′-Dimethoxy-4,4′,9-liganetriol (9). Colorless oil; [α]D25 −24 (c 1.0, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.90 (3H, d, J = 6.9 Hz), 1.40−1.70 (1H, br), 1.77 (1H, m), 1.88 (1H, dq, J = 6.9, 3.3 Hz), 2.39 (1H, dd, J = 13.8, 8.1 Hz), 2.53 (1H, dd, J = 13.8, 7.6 Hz), 2.65 (1H, dd, J = 13.8,
measured with a Horiba SEPA-200 instrument. NMR data were obtained with a JNM-ECS400 spectrometer, using tetramethylsilane and trifluoroacetic acid as a standard (0 ppm) for 1H NMR and (−76.5 ppm) for 19F-NMR, respectively. EIMS data were measured with a JMS-MS700 V spectrometer. The synthetic methods are described in Supporting Information. The numbering of compounds follows the nomenclature of lignans.19 (8R,8′R)-4,4′-Dihydroxy-3,3′-dimethoxylignane-9,9′-diyl diacetate (6). Colorless crystals; mp 108−110 °C; [α]D25 −30 (c 1.3, CHCl3); 1H NMR (400 MHz, CDCl3) δ 2.07 (6H, s), 2.07−2.11 (2H, overlapped), 2.61 (4H, m), 3.78 (6H, s), 4.03 (2H, dd, J = 11.4, 5.7 Hz), 4.20 (2H, dd, J = 11.4, 5.9 Hz), 5.62 (2H, br. s), 6.47 (2H, d, J = 2.0 Hz), 6.55 (2H, dd, J = 8.0, 2.0 Hz), 6.79 (2H, d, J = 8.0 Hz); 13C NMR (100 MHz, CDCl3) δ 21.0, 35.1, 39.6, 55.8, 64.5, 111.2, 114.2, 121.7, 131.5, 144.0, 146.5, 171.1; MS (EI) m/z 446 (M+, 42), 189 (19), 137 (100); HRMS (EI) m/z calcd for C24H30O8 446.1941, found 446.1940. (8R,8′R)- 3,3′,9,9′-Tetramethoxy-4,4′-lignanediol (7). Colorless oil; [α]D25 −27 (c 1.1, CHCl3); 1H NMR (400 MHz, CDCl3) δ 2.01 (2H, m), 2.61 (4H, d, J = 7.3 Hz), 3.28 (2H, dd, 5306
dx.doi.org/10.1021/jf5010572 | J. Agric. Food Chem. 2014, 62, 5305−5315
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Scheme 1. Syntheses of 9- and 9′-Derivatives of (8R,8′R)-Dihydroguaiaretic Acid
(8R,8′R)-3,3′-Dimethoxy-4,4′-dihydroxyligan-9-yl acetate (10). Colorless oil; [α]D25 −28 (c 0.8, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.91 (3H, d, J = 7.1 Hz), 1.83 (1H, dq, J = 7.1, 3.1 Hz), 1.94 (1H, m), 2.06 (3H, s), 2.40 (1H, dd, J = 13.7, 7.8 Hz), 2.52 (1H, dd, J = 13.9, 8.2 Hz), 2.61 (1H, dd, J = 13.7, 6.9 Hz), 2.62 (1H, dd, J = 13.9, 6.5 Hz), 3.78 (3H, s), 3.79 (3H, s), 4.00 (1H, dd, J = 11.2, 6.7 Hz), 4.19 (1H, dd, J = 11.2, 5.8 Hz), 5.53 (1H, s), 5.55 (1H, s), 6.47−6.48 (2H, m), 6.55 (1H, dd, J = 8.0, 2.0 Hz), 6.57 (1H, dd, J = 7.9, 1.9 Hz), 6.79 (1H, d, J = 8.0 Hz), 6.80 (1H, d, J = 7.9 Hz); 13C NMR (100 MHz, CDCl3) δ 15.2, 21.1, 35.0, 35.4, 40.6, 41.9, 55.7, 55.8,
7.0 Hz), 2.67 (1H, dd, J = 13.8, 7.5 Hz), 3.57 (1H, dd, J = 10.9, 6.6 Hz), 3.72 (1H, dd, J = 10.9, 5.3 Hz), 3.77 (3H, s), 3.78 (3H, s), 5.64 (2H, br s), 6.50 (1H, d, J = 1.9 Hz), 6.54 (1H, d, J = 1.9 Hz), 6.57 (1H, dd, J = 8.0, 1.8 Hz), 6.61 (1H, dd, J = 8.0, 1.8 Hz), 6.78 (1H, d, J = 8.0 Hz), 6.80 (1H, d, J = 8.0 Hz); 13C NMR (100 MHz, CDCl3) δ 15.6, 35.0, 35.3, 40.5, 45.8, 55.75, 55.78, 63.0, 111.29, 111.34, 114.0, 114.1, 121.67, 121.71, 132.9, 133.2, 143.6, 143.7, 146.4, 146.5; MS (EI) m/z 346 (M+, 11), 137 (100), 122 (14); HRMS (EI) m/z calcd for C20H26O5 346.17808, found 346.17811. 5307
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HRMS (EI) m/z calcd for C23H32O4 372.2302, found 372.2305. (8R,8′R)-9-(N,N-Dimethylamino)-3,3′-dimethoxylignane4,4′-diol (15). Colorless oil; [α]D25 −59 (c 0.4, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.85 (3H, d, J = 7.0 Hz), 1.71 (1H, m), 1.86 (1H, dq, J = 7.0, 2.3 Hz), 2.15−2.24 (2H, overlapped), 2.20 (6H, s), 2.33 (1H, dd, J = 13.8, 9.7 Hz), 2.39 (1H, dd, J = 13.7, 7.1 Hz), 2.49 (1H, dd, J = 13.7, 8.4 Hz), 2.77 (1H, dd, J = 13.8, 5.1 Hz), 3.71 (3H, s), 3.76 (3H, s), 6.39 (1H, d, J = 1.8 Hz), 6.46 (1H, d, J = 1.8 Hz), 6.51 (1H, dd, J = 8.0, 1.8 Hz), 6.55 (1H, dd, J = 8.0, 1.8 Hz), 6.74 (1H, d, J = 8.0 Hz), 6.77 (1H, d, J = 8.0 Hz); 13C NMR (100 MHz, CDCl3) δ 14.8, 33.9, 36.3, 40.0, 40.2, 46.2, 55.6, 55.7, 60.1, 111.1, 111.3, 113.7, 113.8, 121.7, 121.8, 133.3, 133.5, 143.49, 143.54, 146.3; MS (EI) m/z 373 (M+, 100), 164 (20), 137 (43); HRMS (EI) m/z calcd for C22H31O4N 373.2254, found 373.2260. (8R,8′R)-2-Butoxy-3′-methoxy-4′-lignanol (19). Colorless oil; [α]D25 −42 (c 0.8, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.81 (3H, d, J = 6.9 Hz), 0.85 (3H, d, J = 6.7 Hz), 0.96 (3H, t, J = 7.4 Hz), 1.46 (2H, m), 1.68 (2H, m), 1.75 (1H, m), 1.85 (1H, m), 2.35 (1H, dd, J = 13.6, 8.4 Hz), 2.38 (1H, dd, J = 12.9, 8.2 Hz), 2.57 (1H, dd, J = 13.6, 6.8 Hz), 2.69 (1H, dd, J = 12.9, 6.2 Hz), 3.78−3.84 (1H, overlapped), 3.80 (3H, s), 3.90 (1H, m), 5.43 (1H, s), 6.53 (1H, d, J = 1.8 Hz), 6.58 (1H, dd, J = 7.9, 1.8 Hz), 6.78 (2H, br d, J = 7.9 Hz), 6.82 (1H, dd, J = 7.7, 7.3, 1.4 Hz), 7.03 (1H, dd, J = 7.3, 1.5 Hz), 7.12 (1H, ddd, J = 7.8, 7.7, 1.8 Hz); 13C NMR (100 MHz, CDCl3) δ 13.9, 14.1, 14.2, 19.4, 31.5, 35.9, 36.1, 38.6, 41.1, 55.8, 67.3, 110.9, 111.3, 113.9, 119.8, 121.6, 126.8, 130.2, 130.8, 133.9, 143.4, 146.2, 157.2; MS (EI) m/z 356 (M+, 88), 163 (34), 137 (81), 107 (29), 59 (100); HRMS (EI) m/z calcd for C23H32O3 356.2351, found 356.2340. (8R,8′R)-3-Butoxy-3′-methoxy-4′-lignanol (25). Colorless oil; [α]D25 −28 (c 0.6, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.83 (6H, d, J = 6.7 Hz), 0.98 (3H, t, J = 7.4 Hz), 1.49 (2H, m), 1.72−1.82 (4H, m), 2.37 (1H, dd, J = 13.6, 8.1 Hz), 2.41 (1H, dd, J = 13.5, 8.1 Hz), 2.55 (1H, dd, J = 13.6, 6.7 Hz), 2.59 (1H, dd, J = 13.5, 6.7 Hz), 3.82 (3H, s), 3.91 (2H, t, J = 6.5 Hz), 5.45 (1H, s), 6.54 (1H, d, J = 1.7 Hz), 6.59 (1H, dd, J = 8.1, 1.7 Hz), 6.63 (1H, m), 6.67 (1H, br d, J = 7.5 Hz), 6.70 (1H, m), 6.80 (1H, d, J = 8.1 Hz), 7.14 (1H, dd, J = 7.8, 7.8 Hz); 13C NMR (100 MHz, CDCl3) δ 13.9, 14.0, 19.3, 31.5, 37.6, 37.9, 41.1, 41.5, 55.8, 67.5, 111.3, 111.5, 113.9, 115.3, 121.3, 121.6, 128.9, 133.5, 143.3, 143.5, 146.2, 159.0; MS (EI) m/z 356 (M+, 23), 164 (62), 137 (100), 107 (74), 58 (62); HRMS (EI) m/z calcd for C23H32O3 356.2351, found 356.2342. (8R,8′R)-4-Butoxy-3′-methoxy-4′-lignanol (31). Colorless oil; [α]D25 −18 (c 0.7, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.81 (3H, d, J = 6.8 Hz), 0.82 (3H, d, J = 6.8 Hz), 0.98 (3H, t, J = 7.3 Hz), 1.49 (2H, m), 1.70−1.79 (4H, m), 2.36 (1H, dd, J = 13.6, 3.2 Hz), 2.38 (1H, dd, J = 13.5, 3.2 Hz), 2.55 (1H, dd, J = 13.5, 3.5 Hz), 2.56 (1H, dd, J = 13.6, 3.5 Hz), 3.82 (3H, s), 3.93 (2H, t, J = 6.5 Hz), 5.46 (1H, s), 6.54 (1H, d, J = 1.8 Hz), 6.57 (1H, dd, J = 8.1, 1.8 Hz), 6.78 (2H, d, J = 8.5 Hz), 6.80 (1H, d, J = 8.1 Hz), 6.98 (2H, d, J = 8.5 Hz); 13C NMR (100 MHz, CDCl3) δ 13.9, 19.3, 31.5, 37.86, 37.91, 40.5, 41.1, 55.8, 67.7, 111.3, 113.9, 114.1, 121.6, 129.8, 133.5, 133.6, 143.5, 146.2, 157.2; MS (EI) m/z 356 (M+, 12), 208 (39), 137 (99), 107 (74), 58 (100); HRMS (EI) m/z calcd for C23H32O3 356.2351, found 356.2341. (8R,8′R)-4-Methoxy-3-lignanol (44). Colorless oil; [α]D25 −24 (c 0.5, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.81 (3H, d, J = 6.7 Hz), 0.82 (3H, d, J = 6.7 Hz), 1.75−1.83 (2H, m),
64.7, 111.2, 111.3, 114.0, 114.1, 121.7, 132.2, 132.9, 143.7, 143.8, 146.3, 146.4, 171.3; MS (EI) m/z 388 (M+, 25), 137 (100); HRMS (EI) m/z calcd for C22H28O6 388.1886, found 388.1885. (8R,8′R)-3,3′,9-Trimethoxy-4,4′-liganediol (11). Colorless oil; [α]D25 −30 (c 1.0, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.87 (3H, d, J = 6.9 Hz), 1.80−1.88 (2H, m), 2.36 (1H, dd, J = 13.8, 7.8 Hz), 2.49 (1H, dd, J = 13.8, 7.7 Hz), 2.65 (1H, dd, J = 13.8, 7.1 Hz), 2.66 (1H, dd, J = 13.8, 7.0 Hz), 3.25 (1H, dd, J = 9.4, 6.2 Hz), 3.32 (3H, s), 3.40 (1H, dd, J = 9.4, 5.3 Hz), 3.765 (3H, s), 3.772 (3H, s), 5.53 (1H, s), 5.55 (1H, s), 6.48 (1H, d, J = 1.9 Hz), 6.52 (1H, d, J = 1.9 Hz), 6.57 (1H, dd, J = 8.1, 1.9 Hz), 6.59 (1H, dd, J = 8.1, 1.9 Hz), 6.77 (1H, d, J = 8.1 Hz), 6.79 (1H, d, J = 8.1 Hz); 13C NMR (100 MHz, CDCl3) δ 15.4, 34.8, 35.3, 40.7, 43.3, 55.70, 55.74, 58.8, 72.9, 111.28, 111.32, 113.9, 121.79, 121.80, 133.0, 133.4, 143.5, 143.6, 146.3, 146.4; MS (EI) m/z 360 (M+, 14), 137 (100), 122 (14); HRMS (EI) m/z calcd for C21H28O5 360.1937, found 360.1929. (8R,8′R)-9-Fluoro-3,3′-dimethoxy-4,4′-lignanediol (12). Colorless oil; [α]D25 +20 (c 0.2, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.94 (3H, d, J = 6.8 Hz), 1.85−1.98 (2H, m), 2.43 (1H, dd, J = 13.8, 7.6 Hz), 2.56 (1H, dd, J = 13.6, 7.4 Hz), 2.62−2.69 (2H, m), 3.798 (3H, s), 3.803 (3H, s), 4.45 (2H, m), 5.46 (1H, s), 5.48 (1H, s), 6.49 (1H, br s), 6.51 (1H, br s), 6.58 (1H, br d, J = 8.1 Hz), 6.60 (1H, br d, J = 7.7 Hz), 6.79 (1H, dd, J = 7.7, 1.2 Hz), 6.81 (1H, dd, J = 8.1, 1.2 Hz); 13C NMR (100 MHz, CDCl3) δ 15.5, 34.3, 34.8 (d, J = 77.8 Hz), 40.9, 43.8 (d, J = 17.2 Hz), 55.7, 55.8, 84.0 (d, J = 167.7 Hz), 111.15, 111.21, 113.9, 114.0, 121.7, 132.0, 132.8, 143.6, 143.8, 146.3, 146.4; 19F NMR (376 MHz, CDCl3) δ −226.4; MS (EI) m/z (%) 348 (M+, 57), 137 (100); HRMS (EI) m/z calcd for C20H25O4F 348.1737, found 348.1728. (8R,8′R)-3,3′-Dimethoxy-9a,9b,9c,9d-tetrahomolignane4,4′-diol (13). Colorless oil; [α]D25 −37 (c 0.9, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.83 (3H, d, J = 6.9 Hz), 0.89 (3H, t, J = 7.2 Hz), 1.10 (1H, m), 1.24−1.44 (7H, m), 1.49 (1H, m), 1.73 (1H, dq, J = 6.9, 2.3 Hz), 2.33 (1H, dd, J = 13.7, 2.4 Hz), 2.35 (1H, dd, J = 13.7, 4.1 Hz), 2.47 (1H, dd, J = 13.7, 7.8 Hz), 2.57 (1H, dd, J = 13.7, 5.9 Hz), 3.75 (3H, s), 3.77 (3H, s), 5.49 (2H, s), 6.41 (1H, d, J = 1.8 Hz), 6.44 (1H, d, J = 1.8 Hz), 6.51 (1H, dd, J = 8.0, 1.9 Hz), 6.55 (1H, dd, J = 8.0, 1.9 Hz), 6.77 (1H, d, J = 8.0 Hz), 6.78 (1H, d, J = 8.0 Hz); 13C NMR (100 MHz, CDCl3) δ 14.1, 14.8, 22.7, 27.7, 28.9, 32.4, 35.4, 37.5, 40.3, 42.3, 55.65, 55.73, 111.19, 111.24, 113.79, 113.83, 121.69, 121.73, 133.7, 133.8, 143.4, 146.2, 146.3; MS (EI) m/z 386 (M+, 49), 137 (100); HRMS (EI) m/z calcd for C24H34O4 386.2458, found 386.2449. (8R,8′R)-3,3′-Dimethoxy-9a,9b,9b-trihomoligane-4,4′-diol (14). Colorless crystals; mp 70−71 °C; [α]D25 −41 (c 0.4, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.83 (3H, d, J = 6.9 Hz), 0.84 (3H, d, J = 6.5 Hz), 0.89 (3H, d, J = 6.6 Hz), 1.08 (1H, ddd, J = 18.2, 4.9, 4.9 Hz), 1.18 (1H, ddd, J = 18.2, 3.9, 3.9 Hz), 1.58−1.66 (2H, m), 1.75 (1H, dq, J = 6.6, 2.2 Hz), 2.31 (1H, dd, J = 14.0, 9.6 Hz), 2.34 (1H, dd, J = 14.0, 6.8 Hz), 2.43 (1H, dd, J = 13.8, 8.0 Hz), 2.56 (1H, dd, J = 13.8, 5.4 Hz), 3.74 (3H, s), 3.77 (3H, s), 5.44 (1H, s), 5.45 (1H, s), 6.40 (1H, d, J = 1.9 Hz), 6.43 (1H, d, J = 1.9 Hz), 6.51 (1H, dd, J = 8.0, 1.9 Hz), 6.55 (1H, dd, J = 8.0, 1.9 Hz), 6.76 (1H, d, J = 8.0 Hz), 6.78 (1H, d, J = 8.0 Hz); 13C NMR (100 MHz, CDCl3) δ 14.6, 22.3, 24.0, 25.5, 35.1, 37.6, 38.4, 39.6, 40.2, 55.6, 55.7, 111.16, 111.21, 113.7, 113.8, 121.7, 121.8, 133.6, 133.8, 143.4, 146.2, 146.3; MS (EI) m/z 372 (M+, 33), 137 (100), 122 (13); 5308
dx.doi.org/10.1021/jf5010572 | J. Agric. Food Chem. 2014, 62, 5305−5315
Journal of Agricultural and Food Chemistry
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2.33 (1H, dd, J = 13.5, 5.6 Hz), 2.41 (1H, dd, J = 13.5, 8.7 Hz), 2.57 (1H, dd, J = 13.5, 6.1 Hz), 2.65 (1H, dd, J = 13.5, 6.0 Hz), 3.86 (3H, s), 5.54 (1H, s), 6.56 (1H, dd, J = 8.1, 1.9 Hz), 6.69 (1H, d, J = 1.9 Hz), 6.73 (1H, d, J = 8.1 Hz), 7.10 (2H, d, J = 7.3 Hz), 7.16 (1H, dd, J = 7.3, 7.3 Hz), 7.23−7.27 (2H, m); 13C NMR (100 MHz, CDCl3) δ 13.9, 14.0, 38.2, 38.3, 40.7, 41.4, 56.0, 110.4, 115.1, 120.3, 125.6, 128.1, 129.0, 135.0, 141.7, 144.5, 145.2; MS (EI) m/z 284 (M+, 69), 137 (100), 101 (75), 91 (30); HRMS (EI) m/z calcd for C19H24O2 284.1776, found 284.1768. (8R,8′R)-4-Methoxy-2′,3-lignanediol (45). Colorless oil; [α]D25 −30 (c 0.4, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.83 (3H, d, J = 6.5 Hz), 0.85 (3H, d, J = 6.6 Hz), 1.79 (1H, m), 1.87 (1H, m), 2.34 (1H, dd, J = 13.6, 8.7 Hz), 2.42 (1H, dd, J = 13.6, 8.9 Hz), 2.58 (1H, dd, J = 13.6, 6.2 Hz), 2.67 (1H, dd, J = 13.6, 5.9 Hz), 3.85 (3H, s), 4.78 (1H, s), 5.58 (1H, s), 6.58 (1H, dd, J = 8.1, 2.1 Hz), 6.70−6.74 (3H, m), 6.83 (1H, ddd, J = 7.4, 7.3, 0.9 Hz), 7.03 (1H, dd, J = 7.6, 1.5 Hz), 7.07 (1H, d, J = 7.7, 1.7 Hz); 13C NMR (100 MHz, CDCl3) δ 14.1, 35.4, 36.6, 38.6, 40.7, 56.0, 110.4, 115.1, 115.2, 120.4, 120.5, 127.0, 127.5, 131.1, 135.0, 144.5, 145.1, 153.6; MS (EI) m/z 300 (M+, 90), 137 (100), 107 (27); HRMS (EI) m/z calcd for C19H24O3 300.1725; found 300.1730. (8R,8′R)-2′,4-Methoxy-3-lignanol (46). Colorless oil; [α]D25 −32 (c 0.4, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.81 (3H, d, J = 6.2 Hz), 0.82 (3H, d, J = 6.1 Hz), 1.76 (1H, m), 1.84 (1H, m), 2.33 (1H, dd, J = 13.6, 8.6 Hz), 2.39 (1H, dd, J = 13.2, 8.7 Hz), 2.57 (1H, dd, J = 13.6, 6.4 Hz), 2.69 (1H, dd, J = 13.2, 5.8 Hz), 3.74 (3H, s), 3.85 (3H, s), 5.52 (1H, s), 6.57 (1H, dd, J = 8.2, 2.0 Hz), 6.69 (1H, d, J = 2.0 Hz), 6.73 (1H, d, J = 8.2 Hz), 6.81 (1H, br d, J = 8.1 Hz), 6.85 (1H, ddd, J = 7.6, 7.3, 1.0 Hz), 7.04 (1H, dd, J = 7.3, 1.7 Hz), 7.15 (1H, ddd, J = 7.8, 7.6, 1.7 Hz); 13C NMR (100 MHz, CDCl3) δ 14.06, 14.12, 35.7, 36.3, 38.6, 40.7, 55.1, 56.0, 110.2, 110.3, 115.1, 120.0, 120.4, 126.8, 130.2, 130.6, 135.3, 144.5, 145.2, 157.6; MS (EI) m/z 314 (M+, 100), 137 (88), 121 (45); HRMS (EI) m/z calcd for C20H26O3 314.1882, found 314.1891. (8R,8′R)-2′-Ethoxy-4-methoxy-3-lignanol (47). Colorless oil; [α]D25 −28 (c 0.5, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.80 (3H, d, J = 6.9 Hz), 0.85 (3H, d, J = 6.7 Hz), 1.33 (3H, t, J = 7.0 Hz), 1.75 (1H, m), 1.85 (1H, m), 2.32 (1H, dd, J = 13.6, 8.6 Hz), 2.35 (1H, dd, J = 13.1, 8.7 Hz), 2.58 (1H, dd, J = 13.6, 6.4 Hz), 2.73 (1H, dd, J = 13.1, 5.6 Hz), 3.85 (3H, s), 3.95 (2H, m), 5.51 (1H, s), 6.57 (1H, dd, J = 8.2, 2.1 Hz), 6.68 (1H, d, J = 2.1 Hz), 6.72 (1H, d, J = 8.2 Hz), 6.79 (1H, d, J = 8.0 Hz), 6.83 (1H, dd, J = 7.4, 7.4 Hz), 7.04 (1H, dd, J = 7.4, 1.7 Hz), 7.13 (1H, ddd, J = 7.4, 7.4, 1.7 Hz); 13C NMR (100 MHz, CDCl3) δ 14.2, 14.3, 14.9, 35.8, 36.4, 38.8, 40.6, 56.0, 63.2, 110.3, 111.0, 115.1, 119.9, 120.3, 126.7, 130.3, 130.8, 135.4, 144.5, 145.2, 157.0; MS (EI) m/z 328 (M+, 78), 137 (100), 135 (54); HRMS (EI) m/z calcd for C21H28O3 328.2038, found 328.2020. (8R,8′R)-2′-Butoxy-4-methoxy-3-lignanol (48). Colorless oil; [α]D25 −17 (c 0.5, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.80 (3H, d, J = 6.8 Hz), 0.84 (3H, d, J = 6.8 Hz), 0.97 (3H, t, J = 7.4 Hz), 1.48 (2H, m), 1.71 (2H, m), 1.76 (1H, m), 1.86 (1H, m), 2.30 (1H, dd, J = 13.5, 8.9 Hz), 2.36 (1H, dd, J = 13.0, 8.9 Hz), 2.59 (1H, dd, J = 13.5, 6.1 Hz), 2.72 (1H, dd, J = 13.0, 5.6 Hz), 3.86 (3H, s), 3.89 (2H, m), 5.51 (1H, s), 6.57 (1H, dd, J = 8.1, 2.0 Hz), 6.68 (1H, d, J = 2.0 Hz), 6.72 (1H, d, J = 8.1 Hz), 6.79 (1H, d, J = 8.2 Hz), 6.84 (1H, d, J = 7.3 Hz), 7.04 (1H, dd, J = 7.3, 1.4 Hz), 7.13 (1H, ddd, J = 7.8, 7.7, 1.4 Hz); 13C NMR (100 MHz, CDCl3) δ 13.9, 14.1, 19.4,
31.5, 35.8, 36.6, 38.9, 40.7, 56.0, 67.3, 110.3, 110.9, 115.1, 119.8, 120.3, 126.7, 130.2, 130.8, 135.4, 144.5, 145.2, 157.1; MS (EI) m/z 356 (M+, 61), 208 (33), 163 (20), 137 (100), 107 (26); HRMS (EI) m/z calcd for C23H32O3 356.2351, found 356.2347. (8R,8′R)-2′-Isopropoxy-4-methoxy-3-lignanol (49). Colorless oil; [α]D25 −26 (c 0.4, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.79 (3H, d, J = 6.5 Hz), 0.85 (3H, d, J = 6.8 Hz), 1.24 (3H, d, J = 5.9 Hz), 1.26 (3H, d, J = 6.0 Hz), 1.75−1.88 (2H, m), 2.30 (1H, dd, J = 13.0, 8.7 Hz), 2.32 (1H, dd, J = 13.5, 8.6 Hz), 2.58 (1H, dd, J = 13.5, 6.4 Hz), 2.72 (1H, dd, J = 13.0, 5.2 Hz), 3.85 (3H, s), 4.48 (1H, m), 5.52 (1H, s), 6.57 (1H, dd, J = 8.1, 2.0 Hz), 6.69 (1H, d, J = 2.0 Hz), 6.72 (1H, d, J = 8.1 Hz), 6.78−6.82 (2H, m), 7.04 (1H, dd, J = 7.4, 1.7 Hz), 7.11 (1H, ddd, J = 7.8, 7.1, 1.7 Hz); 13C NMR (100 MHz, CDCl3) δ 14.0, 14.3, 22.0, 22.1, 36.0, 36.4, 39.0, 40.7, 56.0, 69.2, 110.3, 112.3, 115.1, 119.6, 120.3, 126.6, 131.00, 131.04, 135.4, 144.5, 145.2, 155.7; MS (EI) m/z 342 (M+, 92), 137 (100), 107 (50); HRMS (EI) m/z calcd for C22H30O3 342.2195, found 342.2177. (8R,8′R)-4-Methoxy-2′-methyl-3-lignanol (50). Colorless oil; [α]D25 −36 (c 0.4, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.81 (3H, d, J = 6.6 Hz), 0.87 (3H, d, J = 6.8 Hz), 1.73−1.85 (2H, m), 2.21 (3H, s), 2.35 (1H, dd, J = 13.5, 8.3 Hz), 2.39 (1H, dd, J = 13.5, 9.1 Hz), 2.56 (1H, dd, J = 13.5, 6.6 Hz), 2.65 (1H, dd, J = 13.5, 5.2 Hz), 3.85 (3H, s), 5.53 (1H, s), 6.57 (1H, dd, J = 8.1, 2.2 Hz), 6.69 (1H, d, J = 2.2 Hz), 6.73 (1H, d, J = 8.1 Hz), 7.03 (1H, m), 7.07−7.12 (3H, m); 13C NMR (100 MHz, CDCl3) δ 13.7, 14.3, 19.4, 36.5, 38.8, 39.0, 40.6, 56.0, 110.4, 115.1, 120.3, 125.5, 125.7, 129.9, 130.1, 135.0, 136.2, 139.8, 144.6, 145.2; EIMS m/z (%) 298 (M+, 82), 137 (100), 105 (21); HRMS (EI) m/z calcd for C20H26O2 298.1933, found 298.1932. (8R,8′R)-2′-Fluoro-4-methoxy-3-lignanol (51). Colorless oil; [α]D25 −37 (c 0.4, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.83 (3H, d, J = 6.8 Hz), 0.84 (3H, d, J = 6.7 Hz), 1.77 (1H, m), 1.83 (1H, m), 2.32 (1H, dd, J = 13.5, 8.9 Hz), 2.46 (1H, dd, J = 13.5, 8.9 Hz), 2.58 (1H, dd, J = 13.5, 5.9 Hz), 2.69 (1H, dd, J = 13.5, 6.0 Hz), 3.86 (3H, s), 5.54 (1H, s), 6.57 (1H, dd, J = 8.1, 1.9 Hz), 6.68 (1H, d, J = 1.9 Hz), 6.73 (1H, d, J = 8.1 Hz), 6.97 (1H, br d, J = 8.8 Hz), 7.02 (1H, dd, J = 7.3, 6.6 Hz), 7.08 (1H, dd, J = 7.4, 1.6 Hz), 7.14 (1H, m); 13C NMR (100 MHz, CDCl3) δ 13.97, 13.99, 34.1, 37.4, 38.5, 40.7, 56.0, 110.4, 115.09, 115.10 (d, J = 22.3 Hz), 120.3, 123.7 (d, J = 3.7 Hz), 127.3 (d, J = 7.9 Hz), 128.5 (d, J = 15.9 Hz), 131.3 (d, J = 4.8 Hz), 134.9, 144.6, 145.2, 161.3 (d, J = 244.3 Hz); 19F NMR (376 MHz, CDCl3) δ −119.1; MS (EI) m/z 302 (M+, 90), 137 (100); HRMS (EI) m/z calcd for C19H23O2F 302.1682, found 302.1680. (8R,8′R)-4-Methoxy-3,3′-lignanediol (52). Colorless oil; [α]D25 −19 (c 0.5, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.80 (3H, d, J = 6.7 Hz), 0.81 (3H, d, J = 6.7 Hz), 1.73−1.81 (2H, m), 2.36 (1H, dd, J = 13.5, 8.5 Hz), 2.38 (1H, dd, J = 13.5, 8.6 Hz), 2.52 (1H, dd, J = 13.4, 6.5 Hz), 2.57 (1H, dd, J = 13.4, 6.4 Hz), 3.86 (3H, s), 4.90−5.40 (1H, br), 5.65 (1H, br s), 6.54 (1H, dd, J = 2.1, 1.7 Hz), 6.58 (1H, dd, J = 8.2, 2.1 Hz), 6.64− 6.69 (3H, m), 6.74 (1H, d, J = 8.2 Hz), 7.11 (1H, dd, J = 7.8, 7.8 Hz); 13C NMR (100 MHz, CDCl3) δ 13.8, 13.9, 37.1, 37.6, 40.6, 41.1, 56.0, 110.4, 112.7, 115.1, 115.8, 120.6, 121.6, 129.2, 134.9, 143.5, 144.6, 145.0, 155.4; MS (EI) m/z 300 (M+, 91), 137 (100); HRMS (EI) m/z calcd for C19H24O3 300.1725, found 300.1733. 5309
dx.doi.org/10.1021/jf5010572 | J. Agric. Food Chem. 2014, 62, 5305−5315
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Table 1. Cytotoxic Activities of (8R,8′R)-Secoisolariciresinol (1), (8R,8′R)-9,9′-Anhydrosecoisolariciresinol (2), All Stereoisomers of Dihydroguaiaretic Acid (3−5), and 9-,9′-Derivatives of (8R,8′R)-Dihydroguaiaretic Acid 6−15 against HL-60 and HeLa Cells (IC50 ± SD, n = 3)
CDCl3) δ 0.815 (3H, d, J = 6.8 Hz), 0.821 (3H, d, J = 6.7 H), 1.72−1.83 (2H, m), 2.34 (1H, dd, J = 13.5, 8.5 Hz), 2.41 (1H, dd, J = 13.5, 8.6 Hz), 2.55 (1H, dd, J = 13.5, 6.4 Hz), 2.64 (1H, dd, J = 13.5, 6.3 Hz), 3.87 (3H, s), 5.54 (1H, s), 6.56 (1H, d, J = 8.1, 2.1 Hz), 6.68 (1H, d, J = 2.1 Hz), 6.74 (1H, d, J = 8.1 Hz), 6.79 (1H, ddd, J = 10.0, 2.1, 1.7 Hz), 6.83−6.89 (2H, m), 7.20 (1H, ddd, J = 7.8, 7.7, 6.3 Hz): 13C NMR (100 MHz, CDCl3) δ 13.9, 14.0, 37.9, 38.2, 40.7, 41.2, 56.0, 110.4, 112.5 (d, J = 20.8 Hz), 115.1, 115.7 (d, J = 21.0 Hz), 120.3, 124.7, 129.4 (d, J = 8.5 Hz), 134.8, 144.3 (d, J = 7.1 Hz), 144.6, 145.3, 162.8 (d, J = 245.3 Hz); 19F NMR (376 MHz, CDCl3) δ −115.2; MS (EI) m/z 302 (M+, 74), 137 (100); HRMS (EI) m/z calcd for C19H23FO2 302.1682, found 302.1682. (8R,8′R)-4-Methoxy-3,4′-lignanediol (56). Colorless oil; [α]D25 −21 (c 0.5, CHCl3); 1H NMR (CDCl3) δ 0.797 (3H, d, J = 6.5 Hz), 0.801 (3H, d, J = 6.7 Hz), 1.70−1.78 (2H, m), 2.32 (1H, dd, J = 13.5, 8.9 Hz), 2.35 (1H, dd, J = 13.5, 8.9 Hz), 2.55 (1H, dd, J = 13.5, 6.7 Hz), 2.56 (1H, dd, J = 13.5, 6.7 Hz), 3.86 (3H, s), 4.77 (1H, s), 5.56 (1H, s), 6.57 (1H, dd, J = 8.1, 2.0 Hz), 6.68 (1H, d, J = 2.0 Hz), 6.72 (2H, d, J = 8.5 Hz), 6.74 (1H, d, J = 8.1 Hz), 6.95 (2H, d, J = 8.5 Hz); 13C NMR (100 MHz, CDCl3) δ 13.9, 38.1, 38.3, 40.5, 40.8, 56.0, 110.4, 115.0, 115.1, 120.4, 130.0, 133.9, 135.0, 144.5, 145.2, 153.4; MS (EI) m/z 300 (M+, 95), 137 (100), 107 (35); HRMS (EI) m/z calcd for C19H24O3 300.1725, found 300.1731. (8R,8′R)-4,4′-Methoxy-3-lignanol (57). Colorless oil; [α]D25 −22 (c 0.8, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.80 (3H, d, J = 6.7 Hz), 0.81 (3H, d, J = 6.5 Hz), 1.75 (2H, m), 2.32
(8R,8′R)-3′,4-Methoxy-3-lignanol (53). Colorless oil; [α]D25 −25 (c 0.6, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.82 (6H, d, J = 6.8 Hz), 1.73−1.84 (2H, m), 2.33 (1H, dd, J = 13.6, 8.5 Hz), 2.39 (1H, dd, J = 13.4, 8.6 Hz), 2.56 (1H, dd, J = 13.6, 6.3 Hz), 2.62 (1H, dd, J = 13.4, 6.2 Hz), 3.78 (3H, s), 3.86 (3H, s), 5.55 (1H, s), 6.56 (1H, dd, J = 8.2, 1.9 Hz), 6.65 (1H, m), 6.68−6.74 (4H, m), 7.16 (1H, dd, J = 7.9, 7.8 Hz); 13C NMR (100 MHz, CDCl3) δ 14.0, 38.0, 38.2, 40.7, 41.5, 55.1, 56.0, 110.4, 110.9, 114.6, 115.1, 120.3, 121.5, 129.0, 135.0, 143.3, 144.6, 145.2, 159.4; MS (EI) m/z 314 (M+, 100), 137 (96), 122 (37); HRMS (EI) m/z calcd for C20H26O3 314.1882, found 314.1890. (8R,8′R)-4-Methoxy-3′-methyl-3-lignanol (54). Colorless oil; [α]D25 −26 (c 0.6, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.81 (3H, d, J = 6.6 Hz), 0.82 (3H, d, J = 6.7 Hz), 1.73−1.84 (2H, m), 2.30−2.35 (1H, overlapped), 2.31 (3H, s), 2.37 (1H, dd, J = 13.4, 8.6 Hz), 2.57 (1H, dd, J = 13.4, 6.0 Hz), 2.61 (1H, dd, J = 13.4, 6.0 Hz), 3.86 (3H, s), 5.54 (1H, s), 6.57 (1H, dd, J = 8.2, 1.9 Hz), 6.69 (1H, d, J = 1.9 Hz), 6.73 (1H, d, J = 8.2 Hz), 6.90 (1H, br d, J = 7.2 Hz), 6.91 (1H, br s), 6.98 (1H, br d, J = 7.5 Hz), 7.14 (1H, dd, J = 7.5, 7.1 Hz); 13C NMR (100 MHz, CDCl3) δ 14.0, 21.4, 38.0, 38.3, 40.7, 41.3, 56.0, 110.3, 115.1, 120.3, 126.0, 126.3, 128.0, 129.8, 135.0, 137.6, 141.6, 144.5, 145.2; MS (EI) m/z 298 (M+, 25), 137 (100); HRMS (EI) m/z calcd for C20H26O2 298.1933, found 298.1929. (8R,8′R)-3′-Fluoro-4-methoxy-3-lignanol (55). Colorless oil; [α]D25 −26 (c 0.5, CHCl3); 1H NMR (400 MHz, 5310
dx.doi.org/10.1021/jf5010572 | J. Agric. Food Chem. 2014, 62, 5305−5315
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Table 2. Cytotoxic Activities of 7-Aryl Derivatives of (8R,8′R)-Dihydroguaiaretic Acid against HL-60 and HeLa Cells (IC50± SD, n = 3)
no.
R
HL-60 IC50 (μM) ± SD
HeLa IC50 (μM) ± SD
no.
R
HL-60 IC50 (μM) ± SD
HeLa IC50 (μM) ± SD
16 17 18 19 20 21 22 23 24 25 26 27 28 29
H 2-OH 2-OCH3 2-O(CH2)3CH3 2-CH3 2-F 2-Cl 3-OH 3-OCH3 3-O(CH2)3CH3 3-CH3 3-F 3-Cl 4-OH
10.3 ± 2.4 9.6 ± 2.7 6.3 ± 0.2 7.2 ± 2.4 5.9 ± 1.5 13.5 ± 0.8 10.0 ± 0.5 26.1 ± 3.4 27.1 ± 3.3 7.5 ± 2.2 15.9 ± 2.9 11.0 ± 0.1 9.1 ± 2.6 5.9 ± 0.5
31.8 ± 1.5 9.3 ± 2.0 24.4 ± 0.5 9.3 ± 0.3 17.3 ± 0.4 18.7 ± 0.3 18.5 ± 0.7 26.5 ± 2.1 24.3 ± 0.4 10.6 ± 1.4 18.7 ± 0.4 17.9 ± 1.1 17.0 ± 1.8 10.8 ± 0.8
30 31 32 33 34 35 36 37 38 39 40 41 42 43
4-OCH3 4-O(CH2)3CH3 4-CH3 4-F 4-Cl 3,4-OH 3,5-OH 3,4-OCH3 3-OH-4-OCH3 3-OCH2CH3-4-OH 3,4-OCH2O 3,5-OCH3-4-OH 3,4,5-OH
12.5 ± 1.5 6.6 ± 1.9 16.1 ± 2.0 13.4 ± 2.5 10.6 ± 2.5 5.9 ± 0.2 10.8 ± 0.6 31.9 ± 3.5 8.7 ± 1.2 7.3 ± 1.9 28.6 ± 1.9 9.0 ± 3.6 12.6 ± 1.0 28.9 ± 1.7
27.6 ± 2.6 10.7 ± 1.1 17.5 ± 2.5 19.1 ± 0.3 18.3 ± 0.4 13.6 ± 1.1 7.6 ± 1.0 30.5 ± 1.9 7.5 ± 0.5 27.9 ± 2.8 32.7 ± 2.5 6.8 ± 0.5 34.9 ± 2.4 >100 (36% inhibition)
Cytotoxic Assay. Human cervical carcinoma cell line HeLa cells and human promyelocytic leukemia cell line HL-60 cells were obtained from American Type Culture Collection (Manassas, VA). Colon 26 colon adenocarcinoma cells derived from BALB/c mouse were kindly provided by the Institute of Development, Aging and Cancer, Tohoku University (Sendai, Japan). Vero cells (JCRB0111) were purchased from JCRB Cell Banks. These cells were cultured in the DMEM medium (Sigma, St. Louis, MO) supplemented with 10% fetal bovine serum (FBS) at 37 °C in a humidified atmosphere of 5% CO2. HeLa, Colon 26, and Vero cells were inoculated in 96-well culture plates at 2.0 × 104 cells/well suspended in the DMEM medium, and HL-60 cells were inoculated in 96-well culture plates at 1.0 × 104 cells/well suspended in RPMI1640 with FBS and various concentrations of different compounds. After cultivation for 48 h, the cell viability was assessed by a WST-8 reduction assay (Dojin Laboratories, Japan). The WST-8 reduction activity of the cells is presented as the ratio of cell activity. Briefly, a WST-8 solution was added to the culture medium at 10% concentration and incubated for 1 h at 37 °C prior to colorimetry at 450 nm. The single cytotoxic assay was performed in triplicate.
(1H, dd, J = 13.6, 8.5 Hz), 2.36 (1H, dd, J = 13.6, 8.5 Hz), 2.55 (1H, dd, J = 13.6, 5.9 Hz), 2.59 (1H, dd, J = 13.6, 5.9 Hz), 3.79 (3H, s), 3.86 (3H, s), 5.55 (1H, s), 6.57 (1H, dd, J = 8.1, 2.0 Hz), 6.69 (1H, d, J = 2.0 Hz), 6.73 (1H, d, J = 8.1 Hz), 6.80 (2H, d, J = 8.6 Hz), 7.01 (2H, d, J = 8.6 Hz); 13C NMR (100 MHz, CDCl3) δ 13.9, 38.2, 38.3, 40.5, 40.8, 55.2, 56.0, 110.4, 113.5, 115.1, 120.3, 129.8, 133.7, 135.0, 144.5, 145.2, 157.6; MS (EI) m/z 314 (M+, 89), 137 (75), 121 (100), 101 (28); HRMS (EI) m/z calcd for C20H26O3 314.1882, found 314.1885. (8R,8′R)-4-Methoxy-4′-methyl-3-lignanol (58). Colorless oil; [α]D25 −23 (c 0.5, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.80 (3H, d, J = 6.7 Hz), 0.81 (3H, d, J = 6.7 Hz), 1.77 (2H, m), 2.29−2.35 (1H, overlapped), 2.31 (3H, s), 2.37 (1H, dd, J = 13.3, 8.5 Hz), 2.56 (1H, dd, J = 13.3, 5.9 Hz), 2.61 (1H, dd, J = 13.3, 5.7 Hz), 3.85 (3H, s), 5.55 (1H, s), 6.57 (1H, dd, J = 8.2, 1.9 Hz), 6.69 (1H, d, J = 1.9 Hz), 6.73 (1H, d, J = 8.2 Hz), 6.99 (2H, d, J = 7.9 Hz), 7.06 (2H, d, J = 7.9 Hz); 13 C NMR (100 MHz, CDCl3) δ 13.9, 21.0, 38.2, 38.3, 40.8, 41.0, 56.0, 110.3, 115.1, 120.3, 128.8, 128.9, 134.9, 135.0, 138.5, 144.5, 145.2; MS (EI) m/z 298 (M+, 58), 137 (100), 105 (41); HRMS (EI) m/z calcd for C20H26O2 298.1933, found 298.1930. (8R,8′R)-4′-Fluoro-4-methoxy-3-lignanol (59). Colorless oil; [α]D25 −26 (c 0.6, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.80 (3H, d, J = 6.7 Hz), 0.81 (3H, d, J = 6.5 Hz), 1.70−1.78 (2H, m), 2.33 (1H, dd, J = 13.5, 8.3 Hz), 2.38 (1H, dd, J = 13.5, 8.4 Hz), 2.54 (1H, dd, J = 13.5, 6.1 Hz), 2.60 (1H, dd, J = 13.5, 6.1 Hz), 3.86 (3H, s), 5.54 (1H, s), 6.55 (1H, dd, J = 8.2, 2.0 Hz), 6.68 (1H, d, J = 2.0 Hz), 6.73 (1H, d, J = 8.2 Hz), 6.93 (2H, m), 7.03 (2H, m); 13C NMR (100 MHz, CDCl3) δ 13.8, 13.9, 38.1, 38.2, 40.6, 40.7, 56.0, 110.4, 114.8 (d, J = 21.1 Hz), 115.1, 120.3, 130.2 (d, J = 7.8 Hz), 134.9, 137.2 (d, J = 3.0 Hz), 144.6, 145.2, 161.1 (d, J = 242.6); 19F NMR (376 MHz, CDCl3) δ −119.1; MS (EI) m/z 302 (M+, 92), 137 (100); HRMS (EI) m/z calcd for C19H23FO2 302.1682, found 302.1679.
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RESULTS AND DISCUSSION Syntheses of Derivatives. As shown in Scheme 1, 9- and 9′-derivatives of (8R,8′R)-DGA 6−15 were synthesized from dibenzyloxymatairesinol 61. The aromatic derivatives 16−59 were synthesized by the previously described method15 with modification. Cytotoxic Activities of 9- and 9′-Derivatives against HL-60 and HeLa Cells. Table 1 shows the cytotoxic activity of dietary (8R,8′R)-secoisolariciresinol (SECO) (1) and its 9 and 9′-derivatives against HL-60 and HeLa cells. (8R,8′R)-SECO (1) and (8R,8′R)-9,9′-anhydrosecoisolariciresinol (2), which is a metabolite from (−)-(8R,8′R)-SECO, did not show the remarkable activity at 100 μM, suggesting that the oxidations at 5311
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were reduced. All stereoisomers of dihydroguaiaretic acids exhibited the almost same level of activities (IC50 = 22−41 μM). The stereochemistry of 8 and 8′-positions did not affect the activity. The activity of 9, 9′-acetoxy derivative 6 was 2−3fold less potent than DGA stereoisomers, and the activity of 9, 9′-nitrile derivative 8 was very weak (IC50 > 100 μM); however, a similar level of activity to DGA stereoisomers was observed in 9, 9′-methoxy derivative 7. Compared with inactive tetrahydrofuran structure 2, the disadvantage of the ring structure was suggested. Even if the oxygen atoms are present at 9- and 9′positions, the methoxy derivative kept the activity. For further research on the 9-position, the activities of 9-derivatives of (8R,8′R)-DGA 9−15 were tested. Compared with inactive (−)-(8R,8′R)- SECO (1), 9′-dehydroxy SECO 9 showed the weak activity (IC50 = 79−98 μM). The activities of 9-acetoxy and 9-methoxy DGA derivative 10 and 11 were the same level as those of all stereoisomers of DGA 3−5, 9,9′-acetoxy 6, and 9,9′-methoxy 7 derivative. On the other hand, 9-alkyl DGA derivative 13 and 14 displayed 3−4-fold higher activity than that of (8R,8′R)-DGA (3). The activity level of 9-butyl DGA 13 and 9-isopropyl DGA 14 was similar, indicating the importance of higher hydrophobic structure for the higher activity. Because 9-fluoro derivative 12 showed comparable activity to that of (8R,8′R)-DGA (3), the activity would not be affected by an electron-withdrawing atom. The activity of basic derivative, 9-dimethylamino DGA derivative 15, was very low. The relationship between cytotoxic activity and 9-, 9′-structure of butane-type lignan containing dietary secoisolariciresinol became clear. The higher hydrophobic compounds exhibited higher activity. Cytotoxic Activities of 7-Aryl Derivatives against HL60 and HeLa Cells. As a next step, the effect of the substituent
Table 3. Cytotoxic Activities of (8R,8′R)-7-(3-Hydroxy-4methoxyphenyl)-7′-aryl Dihydroguaiaretic Acid Derivatives against HL-60 and HeLa Cells (IC50 ± SD, n = 3)
no.
R
44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59
H 2′-OH 2′-OCH3 2′-OCH2CH3 2′-O(CH2)3CH3 2′-OCH(CH3)2 2′-CH3 2-F 3′-OH 3′-OCH3 3′-CH3 3′-F 4′-OH 4′-OCH3 4′-CH3 4′-F
HL-60 IC50 (μM) ± SD HeLa IC50 (μM) ± SD 8.2 3.5 1.6 0.8 7.2 3.8 2.7 3.7 8.7 7.1 5.9 9.5 4.3 4.5 5.3 5.8
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
1.8 0.6 0.2 0.4 0.4 0.3 0.04 0.8 0.6 1.2 0.3 0.6 0.4 1.2 1.3 0.7
9.5 3.8 2.6 1.7 6.7 4.3 4.7 4.8 9.7 6.2 5.1 9.5 9.8 5.4 5.9 9.9
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
1.3 1.1 0.6 0.6 1.2 1.0 1.3 0.6 0.7 1.0 0.5 0.2 1.3 1.5 1.1 0.3
9- and 9′-positions on the butane chain are disadvantageous for the activity. This fact was ascertained by the examination using dihydroguaiaretic acids (DGA) 3−5, whose 9- and 9′-positions
Table 4. Cytotoxic Activities of 3, 38, and 47 against Colon 26 and Vero Cells (IC50± SD, n = 3)
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3,4-dimethoxy derivative 37. These facts mean that the hydrophilic disubstituted compound is advantageous for higher activity. The longer-chain derivative, 3-ethoxy-4-hydroxy derivative 39 enhanced the activity, showing 4-fold higher activity than (8R,8′R)-DGA (3) against HL-60 cells; however, similar activity to (8R,8′R)-DGA (3) was observed against HeLa cells. It is noteworthy that 3-hydroxy-4-methoxy derivative 38, in which the positions of substituents are exchanged from that of natural DGA, showed 3-fold more potent activity than (8R,8′R)-DGA (3) against both cells. The positions of the hydrophobic and hydrophilic group affected the activity. The addition of a methoxy group to the 5-position of (8R,8′R)-DGA (3) enhanced the activity. The activity of 3,5methoxy-4-hydroxy derivative 41 was 3-fold more potent than (8R,8′R)-DGA (3) against both cells. Compared with HeLa cells, HL-60 cells were more sensitive to more hydrophilic DGA derivatives. The activity of 3,4,5-hydroxy derivative 42 and pentahydroxy derivative 43 was 2-fold higher and comparable to (8R,8′R)-DGA (3), respectively. On the other hand, against HeLa cells, the activities of 3,4,5-hydroxy derivative 42 and pentahydroxy derivative 43 were similar to and much lower than (8R,8′R)-DGA (3), respectively. The position and the number of hydrophobic and hydrophilic groups affected the activity. The 7-(3-hydroxy-4-methoxy)-7′(3-methoxy-4- hydroxy) derivative 38 showed less than 9 μM IC50 value against both cells. Cytotoxic Activities of 7′-Aryl Derivatives against HL60 and HeLa Cells. With the results of the cytotoxic experiment on 7-aryl derivatives, we selected 3-hydroxy-4methoxyphenyl group as an aryl group for 7-position to detect the effect of the 7′-aryl group on the activity. The cytotoxic activities of 7-(3-hydroxy-4-methoxyphenyl)-7′-aryl derivatives 44−59 were evaluated. The activity of 7′-phenyl derivative 44 was comparable to that of 7′-(3-methoxy-4-hydroxyphenyl) derivative 38. The presence of substituent on 7′-aryl group is not necessary to exhibit the activity level of 38. Introduction of the substituent to the 2′-position of 44 enhanced the activity against both cells. The 2′-hydroxy derivative 45 and 2′-F derivative 51 showed 2-fold higher activity, and 2′-methoxy derivative 46 and 2′-methyl derivative 50 were 5-fold and 3-fold more potent, respectively, than 38 against HL-60 cells. These facts mean that the electron donor substituent is more effective than the hydrophilic and electron-withdrawing substituent on the 2′-position. The activity of 2′-ethoxy derivative 47 was 2fold potent than 2′-methoxy derivative, showing the highest activity among 2′-derivatives; however, the longer and bulky substituent at the 2′-position decreased activity. The butoxy 48 and isopropoxy 49 derivative exhibited 2−4-fold less potent activity than that of the 2′-methoxy derivative. Against HeLa cells, 2′-ethoxy derivative 47 was also most effective among the 2′-derivatives, showing 4-fold higher activity than 38. The shorter alkoxy derivative 46 and longer and bulker alkoxy derivative 48 and 49 showed weaker activity than that of 2′ethoxy derivative 47 against HeLa cells as well as against HL-60 cells. The activities of 2′-methyl derivative 50, 2′-fluoro derivative 51, and 2′-hydroxy derivative 45 were 1.6−2-fold higher than that of 38 against HeLa cells. The 3′- and 4′derivatives 52−59 showed comparable activity to 38 against both cells except for 4′-hydroxy derivative 56 and 4′-methoxy derivative 57, which were 1.6-fold more potent than 38 against HL-60 cells. The presence of substituent on 2′-position of 7-(3hydroxy-4-methoxyphenyl)-7′-aryl derivatives was important for the higher activity. 7-(3-Hydroxy-4-methoxyphenyl)-7′-(2′-
of the aromatic ring on the activity was examined. Table 2 shows the activities of 7-derivatives of (8R,8′R)-DGA. Without a substituent on the 7-aromatic ring, derivative 16 showed 2.6fold higher activity than (8R,8′R)-DGA (3) against HL-60 cells and similar activity to 3 against HeLa cells. It could be assumed that the 3-methoxy group and 4-hydroxy group of 3 do not play an important role to keep 10−30 μM of IC50 values. As for 2substituted derivatives 17−22, all derivatives showed 2−4-fold higher activity than that of (8R,8′R)-DGA (3) against HL-60 cells. The activities of 2-methoxy derivative 18, 2-butoxy derivative 19, and 2-methyl derivative 20 bearing an electron donor group were about 2-fold higher than those of hydrophilic 2-hydroxy derivative 17 and 2-halo derivative 21 and 22 bearing an electron-withdrawing group, suggesting that the hydrophobic and electron donor substituents on the 2-position are favorable for higher activity against HL-60 cells. Because the activity of 2-butoxy derivative 19 was similar to that of 2methoxy derivative 18 against HL-60 cells, the length of alkoxy group would not affect the activity. Against HeLa cells, hydrophilic 2-hydroxy derivative 17 and 2-butoxy derivative 19 bearing a longer alkoxy group exhibited 2-fold higher activity than that of (8R,8′R)-DGA (3). On the other hand, the same level of activities as that of (8R,8′R)-DGA (3) were observed in 2-methoxy derivative 18, 2-methyl derivative 20, and 2-halo derivative 21 and 22. The 2-hydroxy derivative 17 and 2-butoxy derivative 19 showed higher activity than (8R,8′R)-DGA (3) against both cells. The effect of 3-substituent was also examined. It was shown that the activities of 3-hydroxy derivative 23 and 3-methoxy derivative 24 were similar to that of (8R,8′R)-DGA (3) against both HL-60 and HeLa cells. The more hydrophobic derivatives, 3-butoxy derivative 25, 3-methyl derivative 26, 3-fluoro derivative 27, and 3-chloro derivative 28 were 2−3-fold more effective than (8R,8′R)-DGA (3) against HL-60 cells. Against HeLa cells, the activity level of 3-methyl derivative 26, 3-fluoro derivative 27, and 3-chloro derivative 28 was almost the same as that of (8R,8′R)-DGA (3); however, 3butoxy derivative 25 exhibited 2-fold more potent activity than (8R,8′R)-DGA (3). The 3-butoxy derivative 25 bearing a longer and hydrophobic group displayed the highest activity among the 3-substituted derivatives against both cells. In the case of the 4-position, 4-hydroxy derivative 29 and 4-butoxy derivative 31 were 4-fold more potent and 4-methoxy derivative 30 and 4-halide derivative 33 and 34 were 2-fold more potent than that of (8R,8′R)-DGA (3) against HL-60 cells. Against HeLa cells, 2-fold higher activities than that of (8R,8′R)-DGA (3) were observed in 4-hydroxy derivative 29 and 4-butoxy derivative 31. The activities of 4-methyl derivative 32 against HL-60 and HeLa cells and 4-methoxy derivative 30 and 4halide derivative 33 and 34 against HeLa cells were similar to that of (8R,8′R)-DGA (3). The phenolic derivative and longer alkoxy derivative were more effective at the 4-position as well as the 2-position against both cells. The activities of all monosubstituted derivatives are not less potent than that of (8R,8′R)-DGA (3). Especially, the IC50 values of 2-hydroxy derivative 17 and 2-butoxy derivative 19 were less than 10 μM against both HL-60 and HeLa cells. The activities of disubstituted compounds 35−40 were also compared. The 3,4-dihydroxy derivative 35 was 5-fold more potent against HL60 cells and 2-fold more potent against HeLa cells than 3,4dimethoxy derivative 37 and 3,4-methylenedioxy derivative 40, whose activities were similar to that of (8R,8′R)-DGA (3). The 3,5-dihydroxy derivative 36 showed 3-fold and 4-fold higher activity against HL-60 cells and HeLa cells, respectively, than 5313
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Funding
ethoxyphenyl) derivative 47 showed the most potent activity against both cells in this research. The shorter and longer alkoxy group at the 2′-position decreased activity (Table 3). Cytotoxic Activity against Colon 26 and Vero Cells. Finally, the natural (8R,8′R)-DGA (3) and the higher active derivatives 38 and 47 against HL-60 and HeLa cells were applied to cytotoxic assay against colon 26 as colorectal cancer cells and Vero cells as normal cells (Table 4). Although the activities against colon 26 cells were weaker than against HL-60 and HeLa cells, these derivatives were also effective. Especially, the IC50 value of compounds 47 against colon 26 was less than 10 μM. Theses derivatives were also effective against Vero cells; however, their activities were weaker than against HL-60 and HeLa cells. The activity of derivative 38 was 3-fold less active, and derivative 47 showed 4−8.5-fold less activity against Vero cells than against HL-60 and HeLa cells, respectively. The most specific activity against cancer cells was observed in derivative 47. In conclusion, we clarified the structure-cytotoxic activity relationship of butane-type lignan containing dietary lignan, secoisolariciresinol, for the first time. The hydroxy groups on 9and 9′-positions of secoisolariciresinol are disadvantageous for the activity. This fact was confirmed by the appearance of activity of 9- and 9′-reductive type lignan, dihydroguaiaretic acid (DGA), whose all stereoisomers showed same level of activities. In the course of the evaluation of activities of the derivatives, 9-butyl (8R,8′R)-DGA derivative 13, 7-(2-hydroxyphenyl) (8R,8′R)-DGA derivative 17, 7-(2-butoxyphenyl) (8R,8′R)- DGA derivative 19, 7-(3,5-dimethoxy-4-hydroxy (8R,8′R)-DGA derivative 41, and 7-(3-hydroxy-4-methoxyphenyl) (8R,8′R)-DGA derivative 38 showed 2−4-fold higher activity than (8R,8′R)-DGA (3). Finally, 7-(3-hydroxy-4methoxyphenyl)-7′-(2′-ethoxyphenyl) DGA derivative 47 showed highest cytotoxic activity in this research, showing 32-fold and 13-fold higher activity against HL-60 cells (IC50 = 0.8 μM) and HeLa cells (IC50 = 1.7 μM), respectively, than (8R,8′R)-DGA (3). This derivative 47 was also effective against colon 26 cells. Although (8R,8′R)-9,9′-anhydrosecoisolariciresinol (2), which is a candidate for metabolite of dietary secoisolariciresinol, did not show the cytotoxic activity in this research, the higher cytotoxic active dihydroguaiaretic acid (DGA) derivative was prepared as a new lead compound, whose main chemical structure is same as that of dietary secoisolariciresinol. Since there is a possibility that dietary lignan derivatives will be detected as a metabolite, the study on structure−activity relationship of lignan should be promoted to examine the effect of dietary lignan on health and safety. This result would contribute to development of newer lead compounds of medicine based on natural dietary compounds.
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We are grateful to Marutomo Co. for financial support. Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS Part of this study was performed at INCS (Johoku station) of Ehime University. Our thanks to the president of Ehime University for supporting this project.
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ASSOCIATED CONTENT
S Supporting Information *
Supplementary data includes melting points and both NMR and MS data for investigated compounds. Supporting Information also includes additional details for compound syntheses. This material is available free of charge via the Internet at http://pubs.acs.org.
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AUTHOR INFORMATION
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*E-mail: [email protected]. Fax: +81-89-977-4364. Tel.: +81-89-946-9846. 5314
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Cytotoxic Activity of Dietary Lignan and Its Derivatives: Structure− Cytotoxic Activity Relationship of Dihydroguaiaretic Acid Tuti Wukirsari,† Hisashi Nishiwaki,† Kosuke Nishi,† Takuya Sugahara,†,‡ Koichi Akiyama,§ Taro Kishida,†,‡ and Satoshi Yamauchi*,†,‡ †
Faculty of Agriculture and §Integrated Center for Sciences, Tarumi Station, Ehime University, 3-5-7 Tarumi, Matsuyama, Ehime 790-8566, Japan ‡ South Ehime Fisheries Research Center, 1289-1 Funakoshi, Ainan, Ehime 798-4292, Japan S Supporting Information *
ABSTRACT: Cytotoxic activities of synthesized lignan derivatives were estimated by WST-8 reduction assay against HL-60 and HeLa cells to show the structure−activity relationship. The activities of some effective compounds were examined against Colon 26 and Vero cells. Dietary secoisolariciresinol (SECO, 1) and its metabolite, 9,9′-anhydrosecoisolariciresinol (2), did not show the cytotoxic activity. On the other hand, all stereoisomers of dihydroguaiaretic acid (DGA, 9,9′-dehydroxysecoisolariciresinol, 3−5) exhibited the activity (IC50: around 30 μM). The IC50 value of (8R,8′R)-9-butyl DGA derivative 13 was around 6 μM. This fact means that the hydrophobic group was advantageous for higher activity at 9- and 9′-positions. By the evaluation of the effect of 7and 7′-aryl group on the activity, we discovered the highest activity of (8R,8′R)-7-(3-hydroxy-4-methoxyphenyl)-7′-(2ethoxyphenyl) DGA derivative 47 showing around 1 μM of IC50 value, which is about 24-fold higher activity than that of natural (8R,8′R)-DGA. The derivative of dietary lignan showed the high cytotoxic activity. KEYWORDS: lignan, cytotoxic activity, secoisolariciresinol, dihydroguaiaretic acid
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INTRODUCTION Lignans are widely distributed in grains, vegetables, and fruits.1 Applications of dietary and medicinal lignan to the health and food industry, including inhibitory activity of cAMP by dibenzylbutyrolactone and furofuran lignans,2 inhibitor and antagonist of PAF by neoliganan kadsurenone and (+)-dihydroguaiaretic acid,2 biological activity as polyphenol by furofuran lignan,3 IgE-suppressive activity−structure relationship of (−)-matairesinol,4 immunomodulatroy effect of (−)-matairesinol,5 effect of secoisolariciresinol (1) on 3T3-L1 adipocytes,6 inhibition of the discolorlation of yellowtail dark muscle by (−)-matairesinol,7 and cytotoxic activity−structure relationship of morinol A8 have been reported. Dietary lignans have served as lead structures for new clinical candidates from natural products. On the other hand, the research on metabolism of plant lignans to many types of lignans and lignan derivatives are also continuing,9 suggesting that new lignan metabolites would be discovered in the future. This fact suggests that the effect of each lignan and its derivative on health should be clarified by structure−activity relationship research because safety of food is focused. In this study, cytotoxic activity of dietary secoisolariciresinol (1) and its reductive products, dihydroguaiaretic acid stereoisomers (3-5), were examined as a first stage. The effect of the stereochemistry was compared and discussed for the first time. The activity of 9,9′-anhydrosecoisolariciresinol (2), which is proposed as a metabolite compound from secoisolariciresinol,10 was also estimated. As a next stage, we designed the 9- and 9′drivatives 6−15 and the aromatic derivatives 16−59 to clarify the structure−cytotoxic activity relationship for the first time. © 2014 American Chemical Society
To achieve this project, the synthetic route to 9- and 9′derivatives 6−15 was also developed (Figure 1). The effect of the structure between the 8- and 8′-position of butane-type lignan on the cytotoxic activity11 and butane-type lignan as an apoptosis inducer12 have been reported. However, structure−activity relationships on 9- and 9′-positions and 7and 7′-aromatic rings have been unknown. Our purpose is to find out the most advantageous substituent for cytotoxic activity on each portion. The results could give information about the structure−activity relationship of dietary and metabolite lignans, which contribute to development of new clinical medicine based on dietary compounds.
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MATERIALS AND METHODS Chemicals. (−)-Secoisolariciresinol (SECO) (1),13 9,9′anhydrosecoisolariciresinol (2),14 and stereoisomers of dihydroguaiaretic acid (3−5)15,16 were synthesized by the previously described method. The derivatives 6−15 were synthesized by the new synthetic method shown in Scheme 1, and their procedures are described in Supporting Information. The derivatives 16−59 were synthesized by the previously described method15 with modification. NMR data of 16−18, 20−24, 26−30, and 32−43 agreed with those of the literature.17,18 The [α]D values of 20−22, 26−28, and 32−34 were opposite but equal amounts to the corresponding enantiomers in the literature.18 Optical rotation values were Received: Revised: Accepted: Published: 5305
March 2, 2014 May 13, 2014 May 19, 2014 May 19, 2014 dx.doi.org/10.1021/jf5010572 | J. Agric. Food Chem. 2014, 62, 5305−5315
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Figure 1. Butane-type lignans and their derivatives.
J = 9.5, 5.4 Hz), 3.30 (6H, s), 3.35 (2H, dd, J = 9.5, 5.4 Hz), 3.76 (6H, s), 5.58 (2H, s), 6.51 (2H, d, J = 1.9 Hz), 6.59 (2H, dd, J = 7.9, 1.9 Hz), 6.78 (2H, d, J = 7.9 Hz); 13C NMR (100 MHz, CDCl3) δ 35.1, 40.6, 55.7, 58.7, 72.7, 111.3, 113.9, 121.9, 132.9, 143.6, 146.4; MS (EI) m/z 390 (M+, 41), 358 (21), 189 (32), 137 (100); HRMS (EI) m/z calcd for C22H30O6 390.2043, found 390.2050. (8R,8′R)-4,4′-Dihydroxy-3,3′-dimethoxy-9a,9′a-dihomolignane-9a,9′a- dinitrile (8). Colorless oil; [α]D25 +40 (c 0.5, CHCl3); 1H NMR (400 MHz, CDCl3) δ 2.24 (2H, m), 2.36− 2.38 (4H, m), 2.57 (2H, dd, J = 14.0, 9.4 Hz), 2.98 (2H, dd, J = 14.0, 5.0 Hz), 3.88 (6H, s), 5.58 (2H, s), 6.64 (2H, d, J = 1.9 Hz), 6.66 (2H, dd, J = 7.9, 1.9 Hz), 6.87 (2H, d, J = 7.9 Hz); 13 C NMR (100 MHz, CDCl3) δ 19.0, 36.3, 39.3, 56.0, 111.0, 114.7, 118.1, 121.7, 129.6, 144.7, 146.9; EIMS m/z 380 (M+, 43), 137 (100), 122 (12); HRMS (EI) m/z calcd for C22H24O4N2 380.1737, found 380.1739. (8R,8′R)-3,3′-Dimethoxy-4,4′,9-liganetriol (9). Colorless oil; [α]D25 −24 (c 1.0, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.90 (3H, d, J = 6.9 Hz), 1.40−1.70 (1H, br), 1.77 (1H, m), 1.88 (1H, dq, J = 6.9, 3.3 Hz), 2.39 (1H, dd, J = 13.8, 8.1 Hz), 2.53 (1H, dd, J = 13.8, 7.6 Hz), 2.65 (1H, dd, J = 13.8,
measured with a Horiba SEPA-200 instrument. NMR data were obtained with a JNM-ECS400 spectrometer, using tetramethylsilane and trifluoroacetic acid as a standard (0 ppm) for 1H NMR and (−76.5 ppm) for 19F-NMR, respectively. EIMS data were measured with a JMS-MS700 V spectrometer. The synthetic methods are described in Supporting Information. The numbering of compounds follows the nomenclature of lignans.19 (8R,8′R)-4,4′-Dihydroxy-3,3′-dimethoxylignane-9,9′-diyl diacetate (6). Colorless crystals; mp 108−110 °C; [α]D25 −30 (c 1.3, CHCl3); 1H NMR (400 MHz, CDCl3) δ 2.07 (6H, s), 2.07−2.11 (2H, overlapped), 2.61 (4H, m), 3.78 (6H, s), 4.03 (2H, dd, J = 11.4, 5.7 Hz), 4.20 (2H, dd, J = 11.4, 5.9 Hz), 5.62 (2H, br. s), 6.47 (2H, d, J = 2.0 Hz), 6.55 (2H, dd, J = 8.0, 2.0 Hz), 6.79 (2H, d, J = 8.0 Hz); 13C NMR (100 MHz, CDCl3) δ 21.0, 35.1, 39.6, 55.8, 64.5, 111.2, 114.2, 121.7, 131.5, 144.0, 146.5, 171.1; MS (EI) m/z 446 (M+, 42), 189 (19), 137 (100); HRMS (EI) m/z calcd for C24H30O8 446.1941, found 446.1940. (8R,8′R)- 3,3′,9,9′-Tetramethoxy-4,4′-lignanediol (7). Colorless oil; [α]D25 −27 (c 1.1, CHCl3); 1H NMR (400 MHz, CDCl3) δ 2.01 (2H, m), 2.61 (4H, d, J = 7.3 Hz), 3.28 (2H, dd, 5306
dx.doi.org/10.1021/jf5010572 | J. Agric. Food Chem. 2014, 62, 5305−5315
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Scheme 1. Syntheses of 9- and 9′-Derivatives of (8R,8′R)-Dihydroguaiaretic Acid
(8R,8′R)-3,3′-Dimethoxy-4,4′-dihydroxyligan-9-yl acetate (10). Colorless oil; [α]D25 −28 (c 0.8, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.91 (3H, d, J = 7.1 Hz), 1.83 (1H, dq, J = 7.1, 3.1 Hz), 1.94 (1H, m), 2.06 (3H, s), 2.40 (1H, dd, J = 13.7, 7.8 Hz), 2.52 (1H, dd, J = 13.9, 8.2 Hz), 2.61 (1H, dd, J = 13.7, 6.9 Hz), 2.62 (1H, dd, J = 13.9, 6.5 Hz), 3.78 (3H, s), 3.79 (3H, s), 4.00 (1H, dd, J = 11.2, 6.7 Hz), 4.19 (1H, dd, J = 11.2, 5.8 Hz), 5.53 (1H, s), 5.55 (1H, s), 6.47−6.48 (2H, m), 6.55 (1H, dd, J = 8.0, 2.0 Hz), 6.57 (1H, dd, J = 7.9, 1.9 Hz), 6.79 (1H, d, J = 8.0 Hz), 6.80 (1H, d, J = 7.9 Hz); 13C NMR (100 MHz, CDCl3) δ 15.2, 21.1, 35.0, 35.4, 40.6, 41.9, 55.7, 55.8,
7.0 Hz), 2.67 (1H, dd, J = 13.8, 7.5 Hz), 3.57 (1H, dd, J = 10.9, 6.6 Hz), 3.72 (1H, dd, J = 10.9, 5.3 Hz), 3.77 (3H, s), 3.78 (3H, s), 5.64 (2H, br s), 6.50 (1H, d, J = 1.9 Hz), 6.54 (1H, d, J = 1.9 Hz), 6.57 (1H, dd, J = 8.0, 1.8 Hz), 6.61 (1H, dd, J = 8.0, 1.8 Hz), 6.78 (1H, d, J = 8.0 Hz), 6.80 (1H, d, J = 8.0 Hz); 13C NMR (100 MHz, CDCl3) δ 15.6, 35.0, 35.3, 40.5, 45.8, 55.75, 55.78, 63.0, 111.29, 111.34, 114.0, 114.1, 121.67, 121.71, 132.9, 133.2, 143.6, 143.7, 146.4, 146.5; MS (EI) m/z 346 (M+, 11), 137 (100), 122 (14); HRMS (EI) m/z calcd for C20H26O5 346.17808, found 346.17811. 5307
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HRMS (EI) m/z calcd for C23H32O4 372.2302, found 372.2305. (8R,8′R)-9-(N,N-Dimethylamino)-3,3′-dimethoxylignane4,4′-diol (15). Colorless oil; [α]D25 −59 (c 0.4, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.85 (3H, d, J = 7.0 Hz), 1.71 (1H, m), 1.86 (1H, dq, J = 7.0, 2.3 Hz), 2.15−2.24 (2H, overlapped), 2.20 (6H, s), 2.33 (1H, dd, J = 13.8, 9.7 Hz), 2.39 (1H, dd, J = 13.7, 7.1 Hz), 2.49 (1H, dd, J = 13.7, 8.4 Hz), 2.77 (1H, dd, J = 13.8, 5.1 Hz), 3.71 (3H, s), 3.76 (3H, s), 6.39 (1H, d, J = 1.8 Hz), 6.46 (1H, d, J = 1.8 Hz), 6.51 (1H, dd, J = 8.0, 1.8 Hz), 6.55 (1H, dd, J = 8.0, 1.8 Hz), 6.74 (1H, d, J = 8.0 Hz), 6.77 (1H, d, J = 8.0 Hz); 13C NMR (100 MHz, CDCl3) δ 14.8, 33.9, 36.3, 40.0, 40.2, 46.2, 55.6, 55.7, 60.1, 111.1, 111.3, 113.7, 113.8, 121.7, 121.8, 133.3, 133.5, 143.49, 143.54, 146.3; MS (EI) m/z 373 (M+, 100), 164 (20), 137 (43); HRMS (EI) m/z calcd for C22H31O4N 373.2254, found 373.2260. (8R,8′R)-2-Butoxy-3′-methoxy-4′-lignanol (19). Colorless oil; [α]D25 −42 (c 0.8, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.81 (3H, d, J = 6.9 Hz), 0.85 (3H, d, J = 6.7 Hz), 0.96 (3H, t, J = 7.4 Hz), 1.46 (2H, m), 1.68 (2H, m), 1.75 (1H, m), 1.85 (1H, m), 2.35 (1H, dd, J = 13.6, 8.4 Hz), 2.38 (1H, dd, J = 12.9, 8.2 Hz), 2.57 (1H, dd, J = 13.6, 6.8 Hz), 2.69 (1H, dd, J = 12.9, 6.2 Hz), 3.78−3.84 (1H, overlapped), 3.80 (3H, s), 3.90 (1H, m), 5.43 (1H, s), 6.53 (1H, d, J = 1.8 Hz), 6.58 (1H, dd, J = 7.9, 1.8 Hz), 6.78 (2H, br d, J = 7.9 Hz), 6.82 (1H, dd, J = 7.7, 7.3, 1.4 Hz), 7.03 (1H, dd, J = 7.3, 1.5 Hz), 7.12 (1H, ddd, J = 7.8, 7.7, 1.8 Hz); 13C NMR (100 MHz, CDCl3) δ 13.9, 14.1, 14.2, 19.4, 31.5, 35.9, 36.1, 38.6, 41.1, 55.8, 67.3, 110.9, 111.3, 113.9, 119.8, 121.6, 126.8, 130.2, 130.8, 133.9, 143.4, 146.2, 157.2; MS (EI) m/z 356 (M+, 88), 163 (34), 137 (81), 107 (29), 59 (100); HRMS (EI) m/z calcd for C23H32O3 356.2351, found 356.2340. (8R,8′R)-3-Butoxy-3′-methoxy-4′-lignanol (25). Colorless oil; [α]D25 −28 (c 0.6, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.83 (6H, d, J = 6.7 Hz), 0.98 (3H, t, J = 7.4 Hz), 1.49 (2H, m), 1.72−1.82 (4H, m), 2.37 (1H, dd, J = 13.6, 8.1 Hz), 2.41 (1H, dd, J = 13.5, 8.1 Hz), 2.55 (1H, dd, J = 13.6, 6.7 Hz), 2.59 (1H, dd, J = 13.5, 6.7 Hz), 3.82 (3H, s), 3.91 (2H, t, J = 6.5 Hz), 5.45 (1H, s), 6.54 (1H, d, J = 1.7 Hz), 6.59 (1H, dd, J = 8.1, 1.7 Hz), 6.63 (1H, m), 6.67 (1H, br d, J = 7.5 Hz), 6.70 (1H, m), 6.80 (1H, d, J = 8.1 Hz), 7.14 (1H, dd, J = 7.8, 7.8 Hz); 13C NMR (100 MHz, CDCl3) δ 13.9, 14.0, 19.3, 31.5, 37.6, 37.9, 41.1, 41.5, 55.8, 67.5, 111.3, 111.5, 113.9, 115.3, 121.3, 121.6, 128.9, 133.5, 143.3, 143.5, 146.2, 159.0; MS (EI) m/z 356 (M+, 23), 164 (62), 137 (100), 107 (74), 58 (62); HRMS (EI) m/z calcd for C23H32O3 356.2351, found 356.2342. (8R,8′R)-4-Butoxy-3′-methoxy-4′-lignanol (31). Colorless oil; [α]D25 −18 (c 0.7, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.81 (3H, d, J = 6.8 Hz), 0.82 (3H, d, J = 6.8 Hz), 0.98 (3H, t, J = 7.3 Hz), 1.49 (2H, m), 1.70−1.79 (4H, m), 2.36 (1H, dd, J = 13.6, 3.2 Hz), 2.38 (1H, dd, J = 13.5, 3.2 Hz), 2.55 (1H, dd, J = 13.5, 3.5 Hz), 2.56 (1H, dd, J = 13.6, 3.5 Hz), 3.82 (3H, s), 3.93 (2H, t, J = 6.5 Hz), 5.46 (1H, s), 6.54 (1H, d, J = 1.8 Hz), 6.57 (1H, dd, J = 8.1, 1.8 Hz), 6.78 (2H, d, J = 8.5 Hz), 6.80 (1H, d, J = 8.1 Hz), 6.98 (2H, d, J = 8.5 Hz); 13C NMR (100 MHz, CDCl3) δ 13.9, 19.3, 31.5, 37.86, 37.91, 40.5, 41.1, 55.8, 67.7, 111.3, 113.9, 114.1, 121.6, 129.8, 133.5, 133.6, 143.5, 146.2, 157.2; MS (EI) m/z 356 (M+, 12), 208 (39), 137 (99), 107 (74), 58 (100); HRMS (EI) m/z calcd for C23H32O3 356.2351, found 356.2341. (8R,8′R)-4-Methoxy-3-lignanol (44). Colorless oil; [α]D25 −24 (c 0.5, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.81 (3H, d, J = 6.7 Hz), 0.82 (3H, d, J = 6.7 Hz), 1.75−1.83 (2H, m),
64.7, 111.2, 111.3, 114.0, 114.1, 121.7, 132.2, 132.9, 143.7, 143.8, 146.3, 146.4, 171.3; MS (EI) m/z 388 (M+, 25), 137 (100); HRMS (EI) m/z calcd for C22H28O6 388.1886, found 388.1885. (8R,8′R)-3,3′,9-Trimethoxy-4,4′-liganediol (11). Colorless oil; [α]D25 −30 (c 1.0, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.87 (3H, d, J = 6.9 Hz), 1.80−1.88 (2H, m), 2.36 (1H, dd, J = 13.8, 7.8 Hz), 2.49 (1H, dd, J = 13.8, 7.7 Hz), 2.65 (1H, dd, J = 13.8, 7.1 Hz), 2.66 (1H, dd, J = 13.8, 7.0 Hz), 3.25 (1H, dd, J = 9.4, 6.2 Hz), 3.32 (3H, s), 3.40 (1H, dd, J = 9.4, 5.3 Hz), 3.765 (3H, s), 3.772 (3H, s), 5.53 (1H, s), 5.55 (1H, s), 6.48 (1H, d, J = 1.9 Hz), 6.52 (1H, d, J = 1.9 Hz), 6.57 (1H, dd, J = 8.1, 1.9 Hz), 6.59 (1H, dd, J = 8.1, 1.9 Hz), 6.77 (1H, d, J = 8.1 Hz), 6.79 (1H, d, J = 8.1 Hz); 13C NMR (100 MHz, CDCl3) δ 15.4, 34.8, 35.3, 40.7, 43.3, 55.70, 55.74, 58.8, 72.9, 111.28, 111.32, 113.9, 121.79, 121.80, 133.0, 133.4, 143.5, 143.6, 146.3, 146.4; MS (EI) m/z 360 (M+, 14), 137 (100), 122 (14); HRMS (EI) m/z calcd for C21H28O5 360.1937, found 360.1929. (8R,8′R)-9-Fluoro-3,3′-dimethoxy-4,4′-lignanediol (12). Colorless oil; [α]D25 +20 (c 0.2, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.94 (3H, d, J = 6.8 Hz), 1.85−1.98 (2H, m), 2.43 (1H, dd, J = 13.8, 7.6 Hz), 2.56 (1H, dd, J = 13.6, 7.4 Hz), 2.62−2.69 (2H, m), 3.798 (3H, s), 3.803 (3H, s), 4.45 (2H, m), 5.46 (1H, s), 5.48 (1H, s), 6.49 (1H, br s), 6.51 (1H, br s), 6.58 (1H, br d, J = 8.1 Hz), 6.60 (1H, br d, J = 7.7 Hz), 6.79 (1H, dd, J = 7.7, 1.2 Hz), 6.81 (1H, dd, J = 8.1, 1.2 Hz); 13C NMR (100 MHz, CDCl3) δ 15.5, 34.3, 34.8 (d, J = 77.8 Hz), 40.9, 43.8 (d, J = 17.2 Hz), 55.7, 55.8, 84.0 (d, J = 167.7 Hz), 111.15, 111.21, 113.9, 114.0, 121.7, 132.0, 132.8, 143.6, 143.8, 146.3, 146.4; 19F NMR (376 MHz, CDCl3) δ −226.4; MS (EI) m/z (%) 348 (M+, 57), 137 (100); HRMS (EI) m/z calcd for C20H25O4F 348.1737, found 348.1728. (8R,8′R)-3,3′-Dimethoxy-9a,9b,9c,9d-tetrahomolignane4,4′-diol (13). Colorless oil; [α]D25 −37 (c 0.9, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.83 (3H, d, J = 6.9 Hz), 0.89 (3H, t, J = 7.2 Hz), 1.10 (1H, m), 1.24−1.44 (7H, m), 1.49 (1H, m), 1.73 (1H, dq, J = 6.9, 2.3 Hz), 2.33 (1H, dd, J = 13.7, 2.4 Hz), 2.35 (1H, dd, J = 13.7, 4.1 Hz), 2.47 (1H, dd, J = 13.7, 7.8 Hz), 2.57 (1H, dd, J = 13.7, 5.9 Hz), 3.75 (3H, s), 3.77 (3H, s), 5.49 (2H, s), 6.41 (1H, d, J = 1.8 Hz), 6.44 (1H, d, J = 1.8 Hz), 6.51 (1H, dd, J = 8.0, 1.9 Hz), 6.55 (1H, dd, J = 8.0, 1.9 Hz), 6.77 (1H, d, J = 8.0 Hz), 6.78 (1H, d, J = 8.0 Hz); 13C NMR (100 MHz, CDCl3) δ 14.1, 14.8, 22.7, 27.7, 28.9, 32.4, 35.4, 37.5, 40.3, 42.3, 55.65, 55.73, 111.19, 111.24, 113.79, 113.83, 121.69, 121.73, 133.7, 133.8, 143.4, 146.2, 146.3; MS (EI) m/z 386 (M+, 49), 137 (100); HRMS (EI) m/z calcd for C24H34O4 386.2458, found 386.2449. (8R,8′R)-3,3′-Dimethoxy-9a,9b,9b-trihomoligane-4,4′-diol (14). Colorless crystals; mp 70−71 °C; [α]D25 −41 (c 0.4, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.83 (3H, d, J = 6.9 Hz), 0.84 (3H, d, J = 6.5 Hz), 0.89 (3H, d, J = 6.6 Hz), 1.08 (1H, ddd, J = 18.2, 4.9, 4.9 Hz), 1.18 (1H, ddd, J = 18.2, 3.9, 3.9 Hz), 1.58−1.66 (2H, m), 1.75 (1H, dq, J = 6.6, 2.2 Hz), 2.31 (1H, dd, J = 14.0, 9.6 Hz), 2.34 (1H, dd, J = 14.0, 6.8 Hz), 2.43 (1H, dd, J = 13.8, 8.0 Hz), 2.56 (1H, dd, J = 13.8, 5.4 Hz), 3.74 (3H, s), 3.77 (3H, s), 5.44 (1H, s), 5.45 (1H, s), 6.40 (1H, d, J = 1.9 Hz), 6.43 (1H, d, J = 1.9 Hz), 6.51 (1H, dd, J = 8.0, 1.9 Hz), 6.55 (1H, dd, J = 8.0, 1.9 Hz), 6.76 (1H, d, J = 8.0 Hz), 6.78 (1H, d, J = 8.0 Hz); 13C NMR (100 MHz, CDCl3) δ 14.6, 22.3, 24.0, 25.5, 35.1, 37.6, 38.4, 39.6, 40.2, 55.6, 55.7, 111.16, 111.21, 113.7, 113.8, 121.7, 121.8, 133.6, 133.8, 143.4, 146.2, 146.3; MS (EI) m/z 372 (M+, 33), 137 (100), 122 (13); 5308
dx.doi.org/10.1021/jf5010572 | J. Agric. Food Chem. 2014, 62, 5305−5315
Journal of Agricultural and Food Chemistry
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2.33 (1H, dd, J = 13.5, 5.6 Hz), 2.41 (1H, dd, J = 13.5, 8.7 Hz), 2.57 (1H, dd, J = 13.5, 6.1 Hz), 2.65 (1H, dd, J = 13.5, 6.0 Hz), 3.86 (3H, s), 5.54 (1H, s), 6.56 (1H, dd, J = 8.1, 1.9 Hz), 6.69 (1H, d, J = 1.9 Hz), 6.73 (1H, d, J = 8.1 Hz), 7.10 (2H, d, J = 7.3 Hz), 7.16 (1H, dd, J = 7.3, 7.3 Hz), 7.23−7.27 (2H, m); 13C NMR (100 MHz, CDCl3) δ 13.9, 14.0, 38.2, 38.3, 40.7, 41.4, 56.0, 110.4, 115.1, 120.3, 125.6, 128.1, 129.0, 135.0, 141.7, 144.5, 145.2; MS (EI) m/z 284 (M+, 69), 137 (100), 101 (75), 91 (30); HRMS (EI) m/z calcd for C19H24O2 284.1776, found 284.1768. (8R,8′R)-4-Methoxy-2′,3-lignanediol (45). Colorless oil; [α]D25 −30 (c 0.4, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.83 (3H, d, J = 6.5 Hz), 0.85 (3H, d, J = 6.6 Hz), 1.79 (1H, m), 1.87 (1H, m), 2.34 (1H, dd, J = 13.6, 8.7 Hz), 2.42 (1H, dd, J = 13.6, 8.9 Hz), 2.58 (1H, dd, J = 13.6, 6.2 Hz), 2.67 (1H, dd, J = 13.6, 5.9 Hz), 3.85 (3H, s), 4.78 (1H, s), 5.58 (1H, s), 6.58 (1H, dd, J = 8.1, 2.1 Hz), 6.70−6.74 (3H, m), 6.83 (1H, ddd, J = 7.4, 7.3, 0.9 Hz), 7.03 (1H, dd, J = 7.6, 1.5 Hz), 7.07 (1H, d, J = 7.7, 1.7 Hz); 13C NMR (100 MHz, CDCl3) δ 14.1, 35.4, 36.6, 38.6, 40.7, 56.0, 110.4, 115.1, 115.2, 120.4, 120.5, 127.0, 127.5, 131.1, 135.0, 144.5, 145.1, 153.6; MS (EI) m/z 300 (M+, 90), 137 (100), 107 (27); HRMS (EI) m/z calcd for C19H24O3 300.1725; found 300.1730. (8R,8′R)-2′,4-Methoxy-3-lignanol (46). Colorless oil; [α]D25 −32 (c 0.4, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.81 (3H, d, J = 6.2 Hz), 0.82 (3H, d, J = 6.1 Hz), 1.76 (1H, m), 1.84 (1H, m), 2.33 (1H, dd, J = 13.6, 8.6 Hz), 2.39 (1H, dd, J = 13.2, 8.7 Hz), 2.57 (1H, dd, J = 13.6, 6.4 Hz), 2.69 (1H, dd, J = 13.2, 5.8 Hz), 3.74 (3H, s), 3.85 (3H, s), 5.52 (1H, s), 6.57 (1H, dd, J = 8.2, 2.0 Hz), 6.69 (1H, d, J = 2.0 Hz), 6.73 (1H, d, J = 8.2 Hz), 6.81 (1H, br d, J = 8.1 Hz), 6.85 (1H, ddd, J = 7.6, 7.3, 1.0 Hz), 7.04 (1H, dd, J = 7.3, 1.7 Hz), 7.15 (1H, ddd, J = 7.8, 7.6, 1.7 Hz); 13C NMR (100 MHz, CDCl3) δ 14.06, 14.12, 35.7, 36.3, 38.6, 40.7, 55.1, 56.0, 110.2, 110.3, 115.1, 120.0, 120.4, 126.8, 130.2, 130.6, 135.3, 144.5, 145.2, 157.6; MS (EI) m/z 314 (M+, 100), 137 (88), 121 (45); HRMS (EI) m/z calcd for C20H26O3 314.1882, found 314.1891. (8R,8′R)-2′-Ethoxy-4-methoxy-3-lignanol (47). Colorless oil; [α]D25 −28 (c 0.5, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.80 (3H, d, J = 6.9 Hz), 0.85 (3H, d, J = 6.7 Hz), 1.33 (3H, t, J = 7.0 Hz), 1.75 (1H, m), 1.85 (1H, m), 2.32 (1H, dd, J = 13.6, 8.6 Hz), 2.35 (1H, dd, J = 13.1, 8.7 Hz), 2.58 (1H, dd, J = 13.6, 6.4 Hz), 2.73 (1H, dd, J = 13.1, 5.6 Hz), 3.85 (3H, s), 3.95 (2H, m), 5.51 (1H, s), 6.57 (1H, dd, J = 8.2, 2.1 Hz), 6.68 (1H, d, J = 2.1 Hz), 6.72 (1H, d, J = 8.2 Hz), 6.79 (1H, d, J = 8.0 Hz), 6.83 (1H, dd, J = 7.4, 7.4 Hz), 7.04 (1H, dd, J = 7.4, 1.7 Hz), 7.13 (1H, ddd, J = 7.4, 7.4, 1.7 Hz); 13C NMR (100 MHz, CDCl3) δ 14.2, 14.3, 14.9, 35.8, 36.4, 38.8, 40.6, 56.0, 63.2, 110.3, 111.0, 115.1, 119.9, 120.3, 126.7, 130.3, 130.8, 135.4, 144.5, 145.2, 157.0; MS (EI) m/z 328 (M+, 78), 137 (100), 135 (54); HRMS (EI) m/z calcd for C21H28O3 328.2038, found 328.2020. (8R,8′R)-2′-Butoxy-4-methoxy-3-lignanol (48). Colorless oil; [α]D25 −17 (c 0.5, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.80 (3H, d, J = 6.8 Hz), 0.84 (3H, d, J = 6.8 Hz), 0.97 (3H, t, J = 7.4 Hz), 1.48 (2H, m), 1.71 (2H, m), 1.76 (1H, m), 1.86 (1H, m), 2.30 (1H, dd, J = 13.5, 8.9 Hz), 2.36 (1H, dd, J = 13.0, 8.9 Hz), 2.59 (1H, dd, J = 13.5, 6.1 Hz), 2.72 (1H, dd, J = 13.0, 5.6 Hz), 3.86 (3H, s), 3.89 (2H, m), 5.51 (1H, s), 6.57 (1H, dd, J = 8.1, 2.0 Hz), 6.68 (1H, d, J = 2.0 Hz), 6.72 (1H, d, J = 8.1 Hz), 6.79 (1H, d, J = 8.2 Hz), 6.84 (1H, d, J = 7.3 Hz), 7.04 (1H, dd, J = 7.3, 1.4 Hz), 7.13 (1H, ddd, J = 7.8, 7.7, 1.4 Hz); 13C NMR (100 MHz, CDCl3) δ 13.9, 14.1, 19.4,
31.5, 35.8, 36.6, 38.9, 40.7, 56.0, 67.3, 110.3, 110.9, 115.1, 119.8, 120.3, 126.7, 130.2, 130.8, 135.4, 144.5, 145.2, 157.1; MS (EI) m/z 356 (M+, 61), 208 (33), 163 (20), 137 (100), 107 (26); HRMS (EI) m/z calcd for C23H32O3 356.2351, found 356.2347. (8R,8′R)-2′-Isopropoxy-4-methoxy-3-lignanol (49). Colorless oil; [α]D25 −26 (c 0.4, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.79 (3H, d, J = 6.5 Hz), 0.85 (3H, d, J = 6.8 Hz), 1.24 (3H, d, J = 5.9 Hz), 1.26 (3H, d, J = 6.0 Hz), 1.75−1.88 (2H, m), 2.30 (1H, dd, J = 13.0, 8.7 Hz), 2.32 (1H, dd, J = 13.5, 8.6 Hz), 2.58 (1H, dd, J = 13.5, 6.4 Hz), 2.72 (1H, dd, J = 13.0, 5.2 Hz), 3.85 (3H, s), 4.48 (1H, m), 5.52 (1H, s), 6.57 (1H, dd, J = 8.1, 2.0 Hz), 6.69 (1H, d, J = 2.0 Hz), 6.72 (1H, d, J = 8.1 Hz), 6.78−6.82 (2H, m), 7.04 (1H, dd, J = 7.4, 1.7 Hz), 7.11 (1H, ddd, J = 7.8, 7.1, 1.7 Hz); 13C NMR (100 MHz, CDCl3) δ 14.0, 14.3, 22.0, 22.1, 36.0, 36.4, 39.0, 40.7, 56.0, 69.2, 110.3, 112.3, 115.1, 119.6, 120.3, 126.6, 131.00, 131.04, 135.4, 144.5, 145.2, 155.7; MS (EI) m/z 342 (M+, 92), 137 (100), 107 (50); HRMS (EI) m/z calcd for C22H30O3 342.2195, found 342.2177. (8R,8′R)-4-Methoxy-2′-methyl-3-lignanol (50). Colorless oil; [α]D25 −36 (c 0.4, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.81 (3H, d, J = 6.6 Hz), 0.87 (3H, d, J = 6.8 Hz), 1.73−1.85 (2H, m), 2.21 (3H, s), 2.35 (1H, dd, J = 13.5, 8.3 Hz), 2.39 (1H, dd, J = 13.5, 9.1 Hz), 2.56 (1H, dd, J = 13.5, 6.6 Hz), 2.65 (1H, dd, J = 13.5, 5.2 Hz), 3.85 (3H, s), 5.53 (1H, s), 6.57 (1H, dd, J = 8.1, 2.2 Hz), 6.69 (1H, d, J = 2.2 Hz), 6.73 (1H, d, J = 8.1 Hz), 7.03 (1H, m), 7.07−7.12 (3H, m); 13C NMR (100 MHz, CDCl3) δ 13.7, 14.3, 19.4, 36.5, 38.8, 39.0, 40.6, 56.0, 110.4, 115.1, 120.3, 125.5, 125.7, 129.9, 130.1, 135.0, 136.2, 139.8, 144.6, 145.2; EIMS m/z (%) 298 (M+, 82), 137 (100), 105 (21); HRMS (EI) m/z calcd for C20H26O2 298.1933, found 298.1932. (8R,8′R)-2′-Fluoro-4-methoxy-3-lignanol (51). Colorless oil; [α]D25 −37 (c 0.4, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.83 (3H, d, J = 6.8 Hz), 0.84 (3H, d, J = 6.7 Hz), 1.77 (1H, m), 1.83 (1H, m), 2.32 (1H, dd, J = 13.5, 8.9 Hz), 2.46 (1H, dd, J = 13.5, 8.9 Hz), 2.58 (1H, dd, J = 13.5, 5.9 Hz), 2.69 (1H, dd, J = 13.5, 6.0 Hz), 3.86 (3H, s), 5.54 (1H, s), 6.57 (1H, dd, J = 8.1, 1.9 Hz), 6.68 (1H, d, J = 1.9 Hz), 6.73 (1H, d, J = 8.1 Hz), 6.97 (1H, br d, J = 8.8 Hz), 7.02 (1H, dd, J = 7.3, 6.6 Hz), 7.08 (1H, dd, J = 7.4, 1.6 Hz), 7.14 (1H, m); 13C NMR (100 MHz, CDCl3) δ 13.97, 13.99, 34.1, 37.4, 38.5, 40.7, 56.0, 110.4, 115.09, 115.10 (d, J = 22.3 Hz), 120.3, 123.7 (d, J = 3.7 Hz), 127.3 (d, J = 7.9 Hz), 128.5 (d, J = 15.9 Hz), 131.3 (d, J = 4.8 Hz), 134.9, 144.6, 145.2, 161.3 (d, J = 244.3 Hz); 19F NMR (376 MHz, CDCl3) δ −119.1; MS (EI) m/z 302 (M+, 90), 137 (100); HRMS (EI) m/z calcd for C19H23O2F 302.1682, found 302.1680. (8R,8′R)-4-Methoxy-3,3′-lignanediol (52). Colorless oil; [α]D25 −19 (c 0.5, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.80 (3H, d, J = 6.7 Hz), 0.81 (3H, d, J = 6.7 Hz), 1.73−1.81 (2H, m), 2.36 (1H, dd, J = 13.5, 8.5 Hz), 2.38 (1H, dd, J = 13.5, 8.6 Hz), 2.52 (1H, dd, J = 13.4, 6.5 Hz), 2.57 (1H, dd, J = 13.4, 6.4 Hz), 3.86 (3H, s), 4.90−5.40 (1H, br), 5.65 (1H, br s), 6.54 (1H, dd, J = 2.1, 1.7 Hz), 6.58 (1H, dd, J = 8.2, 2.1 Hz), 6.64− 6.69 (3H, m), 6.74 (1H, d, J = 8.2 Hz), 7.11 (1H, dd, J = 7.8, 7.8 Hz); 13C NMR (100 MHz, CDCl3) δ 13.8, 13.9, 37.1, 37.6, 40.6, 41.1, 56.0, 110.4, 112.7, 115.1, 115.8, 120.6, 121.6, 129.2, 134.9, 143.5, 144.6, 145.0, 155.4; MS (EI) m/z 300 (M+, 91), 137 (100); HRMS (EI) m/z calcd for C19H24O3 300.1725, found 300.1733. 5309
dx.doi.org/10.1021/jf5010572 | J. Agric. Food Chem. 2014, 62, 5305−5315
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Table 1. Cytotoxic Activities of (8R,8′R)-Secoisolariciresinol (1), (8R,8′R)-9,9′-Anhydrosecoisolariciresinol (2), All Stereoisomers of Dihydroguaiaretic Acid (3−5), and 9-,9′-Derivatives of (8R,8′R)-Dihydroguaiaretic Acid 6−15 against HL-60 and HeLa Cells (IC50 ± SD, n = 3)
CDCl3) δ 0.815 (3H, d, J = 6.8 Hz), 0.821 (3H, d, J = 6.7 H), 1.72−1.83 (2H, m), 2.34 (1H, dd, J = 13.5, 8.5 Hz), 2.41 (1H, dd, J = 13.5, 8.6 Hz), 2.55 (1H, dd, J = 13.5, 6.4 Hz), 2.64 (1H, dd, J = 13.5, 6.3 Hz), 3.87 (3H, s), 5.54 (1H, s), 6.56 (1H, d, J = 8.1, 2.1 Hz), 6.68 (1H, d, J = 2.1 Hz), 6.74 (1H, d, J = 8.1 Hz), 6.79 (1H, ddd, J = 10.0, 2.1, 1.7 Hz), 6.83−6.89 (2H, m), 7.20 (1H, ddd, J = 7.8, 7.7, 6.3 Hz): 13C NMR (100 MHz, CDCl3) δ 13.9, 14.0, 37.9, 38.2, 40.7, 41.2, 56.0, 110.4, 112.5 (d, J = 20.8 Hz), 115.1, 115.7 (d, J = 21.0 Hz), 120.3, 124.7, 129.4 (d, J = 8.5 Hz), 134.8, 144.3 (d, J = 7.1 Hz), 144.6, 145.3, 162.8 (d, J = 245.3 Hz); 19F NMR (376 MHz, CDCl3) δ −115.2; MS (EI) m/z 302 (M+, 74), 137 (100); HRMS (EI) m/z calcd for C19H23FO2 302.1682, found 302.1682. (8R,8′R)-4-Methoxy-3,4′-lignanediol (56). Colorless oil; [α]D25 −21 (c 0.5, CHCl3); 1H NMR (CDCl3) δ 0.797 (3H, d, J = 6.5 Hz), 0.801 (3H, d, J = 6.7 Hz), 1.70−1.78 (2H, m), 2.32 (1H, dd, J = 13.5, 8.9 Hz), 2.35 (1H, dd, J = 13.5, 8.9 Hz), 2.55 (1H, dd, J = 13.5, 6.7 Hz), 2.56 (1H, dd, J = 13.5, 6.7 Hz), 3.86 (3H, s), 4.77 (1H, s), 5.56 (1H, s), 6.57 (1H, dd, J = 8.1, 2.0 Hz), 6.68 (1H, d, J = 2.0 Hz), 6.72 (2H, d, J = 8.5 Hz), 6.74 (1H, d, J = 8.1 Hz), 6.95 (2H, d, J = 8.5 Hz); 13C NMR (100 MHz, CDCl3) δ 13.9, 38.1, 38.3, 40.5, 40.8, 56.0, 110.4, 115.0, 115.1, 120.4, 130.0, 133.9, 135.0, 144.5, 145.2, 153.4; MS (EI) m/z 300 (M+, 95), 137 (100), 107 (35); HRMS (EI) m/z calcd for C19H24O3 300.1725, found 300.1731. (8R,8′R)-4,4′-Methoxy-3-lignanol (57). Colorless oil; [α]D25 −22 (c 0.8, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.80 (3H, d, J = 6.7 Hz), 0.81 (3H, d, J = 6.5 Hz), 1.75 (2H, m), 2.32
(8R,8′R)-3′,4-Methoxy-3-lignanol (53). Colorless oil; [α]D25 −25 (c 0.6, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.82 (6H, d, J = 6.8 Hz), 1.73−1.84 (2H, m), 2.33 (1H, dd, J = 13.6, 8.5 Hz), 2.39 (1H, dd, J = 13.4, 8.6 Hz), 2.56 (1H, dd, J = 13.6, 6.3 Hz), 2.62 (1H, dd, J = 13.4, 6.2 Hz), 3.78 (3H, s), 3.86 (3H, s), 5.55 (1H, s), 6.56 (1H, dd, J = 8.2, 1.9 Hz), 6.65 (1H, m), 6.68−6.74 (4H, m), 7.16 (1H, dd, J = 7.9, 7.8 Hz); 13C NMR (100 MHz, CDCl3) δ 14.0, 38.0, 38.2, 40.7, 41.5, 55.1, 56.0, 110.4, 110.9, 114.6, 115.1, 120.3, 121.5, 129.0, 135.0, 143.3, 144.6, 145.2, 159.4; MS (EI) m/z 314 (M+, 100), 137 (96), 122 (37); HRMS (EI) m/z calcd for C20H26O3 314.1882, found 314.1890. (8R,8′R)-4-Methoxy-3′-methyl-3-lignanol (54). Colorless oil; [α]D25 −26 (c 0.6, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.81 (3H, d, J = 6.6 Hz), 0.82 (3H, d, J = 6.7 Hz), 1.73−1.84 (2H, m), 2.30−2.35 (1H, overlapped), 2.31 (3H, s), 2.37 (1H, dd, J = 13.4, 8.6 Hz), 2.57 (1H, dd, J = 13.4, 6.0 Hz), 2.61 (1H, dd, J = 13.4, 6.0 Hz), 3.86 (3H, s), 5.54 (1H, s), 6.57 (1H, dd, J = 8.2, 1.9 Hz), 6.69 (1H, d, J = 1.9 Hz), 6.73 (1H, d, J = 8.2 Hz), 6.90 (1H, br d, J = 7.2 Hz), 6.91 (1H, br s), 6.98 (1H, br d, J = 7.5 Hz), 7.14 (1H, dd, J = 7.5, 7.1 Hz); 13C NMR (100 MHz, CDCl3) δ 14.0, 21.4, 38.0, 38.3, 40.7, 41.3, 56.0, 110.3, 115.1, 120.3, 126.0, 126.3, 128.0, 129.8, 135.0, 137.6, 141.6, 144.5, 145.2; MS (EI) m/z 298 (M+, 25), 137 (100); HRMS (EI) m/z calcd for C20H26O2 298.1933, found 298.1929. (8R,8′R)-3′-Fluoro-4-methoxy-3-lignanol (55). Colorless oil; [α]D25 −26 (c 0.5, CHCl3); 1H NMR (400 MHz, 5310
dx.doi.org/10.1021/jf5010572 | J. Agric. Food Chem. 2014, 62, 5305−5315
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Table 2. Cytotoxic Activities of 7-Aryl Derivatives of (8R,8′R)-Dihydroguaiaretic Acid against HL-60 and HeLa Cells (IC50± SD, n = 3)
no.
R
HL-60 IC50 (μM) ± SD
HeLa IC50 (μM) ± SD
no.
R
HL-60 IC50 (μM) ± SD
HeLa IC50 (μM) ± SD
16 17 18 19 20 21 22 23 24 25 26 27 28 29
H 2-OH 2-OCH3 2-O(CH2)3CH3 2-CH3 2-F 2-Cl 3-OH 3-OCH3 3-O(CH2)3CH3 3-CH3 3-F 3-Cl 4-OH
10.3 ± 2.4 9.6 ± 2.7 6.3 ± 0.2 7.2 ± 2.4 5.9 ± 1.5 13.5 ± 0.8 10.0 ± 0.5 26.1 ± 3.4 27.1 ± 3.3 7.5 ± 2.2 15.9 ± 2.9 11.0 ± 0.1 9.1 ± 2.6 5.9 ± 0.5
31.8 ± 1.5 9.3 ± 2.0 24.4 ± 0.5 9.3 ± 0.3 17.3 ± 0.4 18.7 ± 0.3 18.5 ± 0.7 26.5 ± 2.1 24.3 ± 0.4 10.6 ± 1.4 18.7 ± 0.4 17.9 ± 1.1 17.0 ± 1.8 10.8 ± 0.8
30 31 32 33 34 35 36 37 38 39 40 41 42 43
4-OCH3 4-O(CH2)3CH3 4-CH3 4-F 4-Cl 3,4-OH 3,5-OH 3,4-OCH3 3-OH-4-OCH3 3-OCH2CH3-4-OH 3,4-OCH2O 3,5-OCH3-4-OH 3,4,5-OH
12.5 ± 1.5 6.6 ± 1.9 16.1 ± 2.0 13.4 ± 2.5 10.6 ± 2.5 5.9 ± 0.2 10.8 ± 0.6 31.9 ± 3.5 8.7 ± 1.2 7.3 ± 1.9 28.6 ± 1.9 9.0 ± 3.6 12.6 ± 1.0 28.9 ± 1.7
27.6 ± 2.6 10.7 ± 1.1 17.5 ± 2.5 19.1 ± 0.3 18.3 ± 0.4 13.6 ± 1.1 7.6 ± 1.0 30.5 ± 1.9 7.5 ± 0.5 27.9 ± 2.8 32.7 ± 2.5 6.8 ± 0.5 34.9 ± 2.4 >100 (36% inhibition)
Cytotoxic Assay. Human cervical carcinoma cell line HeLa cells and human promyelocytic leukemia cell line HL-60 cells were obtained from American Type Culture Collection (Manassas, VA). Colon 26 colon adenocarcinoma cells derived from BALB/c mouse were kindly provided by the Institute of Development, Aging and Cancer, Tohoku University (Sendai, Japan). Vero cells (JCRB0111) were purchased from JCRB Cell Banks. These cells were cultured in the DMEM medium (Sigma, St. Louis, MO) supplemented with 10% fetal bovine serum (FBS) at 37 °C in a humidified atmosphere of 5% CO2. HeLa, Colon 26, and Vero cells were inoculated in 96-well culture plates at 2.0 × 104 cells/well suspended in the DMEM medium, and HL-60 cells were inoculated in 96-well culture plates at 1.0 × 104 cells/well suspended in RPMI1640 with FBS and various concentrations of different compounds. After cultivation for 48 h, the cell viability was assessed by a WST-8 reduction assay (Dojin Laboratories, Japan). The WST-8 reduction activity of the cells is presented as the ratio of cell activity. Briefly, a WST-8 solution was added to the culture medium at 10% concentration and incubated for 1 h at 37 °C prior to colorimetry at 450 nm. The single cytotoxic assay was performed in triplicate.
(1H, dd, J = 13.6, 8.5 Hz), 2.36 (1H, dd, J = 13.6, 8.5 Hz), 2.55 (1H, dd, J = 13.6, 5.9 Hz), 2.59 (1H, dd, J = 13.6, 5.9 Hz), 3.79 (3H, s), 3.86 (3H, s), 5.55 (1H, s), 6.57 (1H, dd, J = 8.1, 2.0 Hz), 6.69 (1H, d, J = 2.0 Hz), 6.73 (1H, d, J = 8.1 Hz), 6.80 (2H, d, J = 8.6 Hz), 7.01 (2H, d, J = 8.6 Hz); 13C NMR (100 MHz, CDCl3) δ 13.9, 38.2, 38.3, 40.5, 40.8, 55.2, 56.0, 110.4, 113.5, 115.1, 120.3, 129.8, 133.7, 135.0, 144.5, 145.2, 157.6; MS (EI) m/z 314 (M+, 89), 137 (75), 121 (100), 101 (28); HRMS (EI) m/z calcd for C20H26O3 314.1882, found 314.1885. (8R,8′R)-4-Methoxy-4′-methyl-3-lignanol (58). Colorless oil; [α]D25 −23 (c 0.5, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.80 (3H, d, J = 6.7 Hz), 0.81 (3H, d, J = 6.7 Hz), 1.77 (2H, m), 2.29−2.35 (1H, overlapped), 2.31 (3H, s), 2.37 (1H, dd, J = 13.3, 8.5 Hz), 2.56 (1H, dd, J = 13.3, 5.9 Hz), 2.61 (1H, dd, J = 13.3, 5.7 Hz), 3.85 (3H, s), 5.55 (1H, s), 6.57 (1H, dd, J = 8.2, 1.9 Hz), 6.69 (1H, d, J = 1.9 Hz), 6.73 (1H, d, J = 8.2 Hz), 6.99 (2H, d, J = 7.9 Hz), 7.06 (2H, d, J = 7.9 Hz); 13 C NMR (100 MHz, CDCl3) δ 13.9, 21.0, 38.2, 38.3, 40.8, 41.0, 56.0, 110.3, 115.1, 120.3, 128.8, 128.9, 134.9, 135.0, 138.5, 144.5, 145.2; MS (EI) m/z 298 (M+, 58), 137 (100), 105 (41); HRMS (EI) m/z calcd for C20H26O2 298.1933, found 298.1930. (8R,8′R)-4′-Fluoro-4-methoxy-3-lignanol (59). Colorless oil; [α]D25 −26 (c 0.6, CHCl3); 1H NMR (400 MHz, CDCl3) δ 0.80 (3H, d, J = 6.7 Hz), 0.81 (3H, d, J = 6.5 Hz), 1.70−1.78 (2H, m), 2.33 (1H, dd, J = 13.5, 8.3 Hz), 2.38 (1H, dd, J = 13.5, 8.4 Hz), 2.54 (1H, dd, J = 13.5, 6.1 Hz), 2.60 (1H, dd, J = 13.5, 6.1 Hz), 3.86 (3H, s), 5.54 (1H, s), 6.55 (1H, dd, J = 8.2, 2.0 Hz), 6.68 (1H, d, J = 2.0 Hz), 6.73 (1H, d, J = 8.2 Hz), 6.93 (2H, m), 7.03 (2H, m); 13C NMR (100 MHz, CDCl3) δ 13.8, 13.9, 38.1, 38.2, 40.6, 40.7, 56.0, 110.4, 114.8 (d, J = 21.1 Hz), 115.1, 120.3, 130.2 (d, J = 7.8 Hz), 134.9, 137.2 (d, J = 3.0 Hz), 144.6, 145.2, 161.1 (d, J = 242.6); 19F NMR (376 MHz, CDCl3) δ −119.1; MS (EI) m/z 302 (M+, 92), 137 (100); HRMS (EI) m/z calcd for C19H23FO2 302.1682, found 302.1679.
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RESULTS AND DISCUSSION Syntheses of Derivatives. As shown in Scheme 1, 9- and 9′-derivatives of (8R,8′R)-DGA 6−15 were synthesized from dibenzyloxymatairesinol 61. The aromatic derivatives 16−59 were synthesized by the previously described method15 with modification. Cytotoxic Activities of 9- and 9′-Derivatives against HL-60 and HeLa Cells. Table 1 shows the cytotoxic activity of dietary (8R,8′R)-secoisolariciresinol (SECO) (1) and its 9 and 9′-derivatives against HL-60 and HeLa cells. (8R,8′R)-SECO (1) and (8R,8′R)-9,9′-anhydrosecoisolariciresinol (2), which is a metabolite from (−)-(8R,8′R)-SECO, did not show the remarkable activity at 100 μM, suggesting that the oxidations at 5311
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were reduced. All stereoisomers of dihydroguaiaretic acids exhibited the almost same level of activities (IC50 = 22−41 μM). The stereochemistry of 8 and 8′-positions did not affect the activity. The activity of 9, 9′-acetoxy derivative 6 was 2−3fold less potent than DGA stereoisomers, and the activity of 9, 9′-nitrile derivative 8 was very weak (IC50 > 100 μM); however, a similar level of activity to DGA stereoisomers was observed in 9, 9′-methoxy derivative 7. Compared with inactive tetrahydrofuran structure 2, the disadvantage of the ring structure was suggested. Even if the oxygen atoms are present at 9- and 9′positions, the methoxy derivative kept the activity. For further research on the 9-position, the activities of 9-derivatives of (8R,8′R)-DGA 9−15 were tested. Compared with inactive (−)-(8R,8′R)- SECO (1), 9′-dehydroxy SECO 9 showed the weak activity (IC50 = 79−98 μM). The activities of 9-acetoxy and 9-methoxy DGA derivative 10 and 11 were the same level as those of all stereoisomers of DGA 3−5, 9,9′-acetoxy 6, and 9,9′-methoxy 7 derivative. On the other hand, 9-alkyl DGA derivative 13 and 14 displayed 3−4-fold higher activity than that of (8R,8′R)-DGA (3). The activity level of 9-butyl DGA 13 and 9-isopropyl DGA 14 was similar, indicating the importance of higher hydrophobic structure for the higher activity. Because 9-fluoro derivative 12 showed comparable activity to that of (8R,8′R)-DGA (3), the activity would not be affected by an electron-withdrawing atom. The activity of basic derivative, 9-dimethylamino DGA derivative 15, was very low. The relationship between cytotoxic activity and 9-, 9′-structure of butane-type lignan containing dietary secoisolariciresinol became clear. The higher hydrophobic compounds exhibited higher activity. Cytotoxic Activities of 7-Aryl Derivatives against HL60 and HeLa Cells. As a next step, the effect of the substituent
Table 3. Cytotoxic Activities of (8R,8′R)-7-(3-Hydroxy-4methoxyphenyl)-7′-aryl Dihydroguaiaretic Acid Derivatives against HL-60 and HeLa Cells (IC50 ± SD, n = 3)
no.
R
44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59
H 2′-OH 2′-OCH3 2′-OCH2CH3 2′-O(CH2)3CH3 2′-OCH(CH3)2 2′-CH3 2-F 3′-OH 3′-OCH3 3′-CH3 3′-F 4′-OH 4′-OCH3 4′-CH3 4′-F
HL-60 IC50 (μM) ± SD HeLa IC50 (μM) ± SD 8.2 3.5 1.6 0.8 7.2 3.8 2.7 3.7 8.7 7.1 5.9 9.5 4.3 4.5 5.3 5.8
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
1.8 0.6 0.2 0.4 0.4 0.3 0.04 0.8 0.6 1.2 0.3 0.6 0.4 1.2 1.3 0.7
9.5 3.8 2.6 1.7 6.7 4.3 4.7 4.8 9.7 6.2 5.1 9.5 9.8 5.4 5.9 9.9
± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±
1.3 1.1 0.6 0.6 1.2 1.0 1.3 0.6 0.7 1.0 0.5 0.2 1.3 1.5 1.1 0.3
9- and 9′-positions on the butane chain are disadvantageous for the activity. This fact was ascertained by the examination using dihydroguaiaretic acids (DGA) 3−5, whose 9- and 9′-positions
Table 4. Cytotoxic Activities of 3, 38, and 47 against Colon 26 and Vero Cells (IC50± SD, n = 3)
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3,4-dimethoxy derivative 37. These facts mean that the hydrophilic disubstituted compound is advantageous for higher activity. The longer-chain derivative, 3-ethoxy-4-hydroxy derivative 39 enhanced the activity, showing 4-fold higher activity than (8R,8′R)-DGA (3) against HL-60 cells; however, similar activity to (8R,8′R)-DGA (3) was observed against HeLa cells. It is noteworthy that 3-hydroxy-4-methoxy derivative 38, in which the positions of substituents are exchanged from that of natural DGA, showed 3-fold more potent activity than (8R,8′R)-DGA (3) against both cells. The positions of the hydrophobic and hydrophilic group affected the activity. The addition of a methoxy group to the 5-position of (8R,8′R)-DGA (3) enhanced the activity. The activity of 3,5methoxy-4-hydroxy derivative 41 was 3-fold more potent than (8R,8′R)-DGA (3) against both cells. Compared with HeLa cells, HL-60 cells were more sensitive to more hydrophilic DGA derivatives. The activity of 3,4,5-hydroxy derivative 42 and pentahydroxy derivative 43 was 2-fold higher and comparable to (8R,8′R)-DGA (3), respectively. On the other hand, against HeLa cells, the activities of 3,4,5-hydroxy derivative 42 and pentahydroxy derivative 43 were similar to and much lower than (8R,8′R)-DGA (3), respectively. The position and the number of hydrophobic and hydrophilic groups affected the activity. The 7-(3-hydroxy-4-methoxy)-7′(3-methoxy-4- hydroxy) derivative 38 showed less than 9 μM IC50 value against both cells. Cytotoxic Activities of 7′-Aryl Derivatives against HL60 and HeLa Cells. With the results of the cytotoxic experiment on 7-aryl derivatives, we selected 3-hydroxy-4methoxyphenyl group as an aryl group for 7-position to detect the effect of the 7′-aryl group on the activity. The cytotoxic activities of 7-(3-hydroxy-4-methoxyphenyl)-7′-aryl derivatives 44−59 were evaluated. The activity of 7′-phenyl derivative 44 was comparable to that of 7′-(3-methoxy-4-hydroxyphenyl) derivative 38. The presence of substituent on 7′-aryl group is not necessary to exhibit the activity level of 38. Introduction of the substituent to the 2′-position of 44 enhanced the activity against both cells. The 2′-hydroxy derivative 45 and 2′-F derivative 51 showed 2-fold higher activity, and 2′-methoxy derivative 46 and 2′-methyl derivative 50 were 5-fold and 3-fold more potent, respectively, than 38 against HL-60 cells. These facts mean that the electron donor substituent is more effective than the hydrophilic and electron-withdrawing substituent on the 2′-position. The activity of 2′-ethoxy derivative 47 was 2fold potent than 2′-methoxy derivative, showing the highest activity among 2′-derivatives; however, the longer and bulky substituent at the 2′-position decreased activity. The butoxy 48 and isopropoxy 49 derivative exhibited 2−4-fold less potent activity than that of the 2′-methoxy derivative. Against HeLa cells, 2′-ethoxy derivative 47 was also most effective among the 2′-derivatives, showing 4-fold higher activity than 38. The shorter alkoxy derivative 46 and longer and bulker alkoxy derivative 48 and 49 showed weaker activity than that of 2′ethoxy derivative 47 against HeLa cells as well as against HL-60 cells. The activities of 2′-methyl derivative 50, 2′-fluoro derivative 51, and 2′-hydroxy derivative 45 were 1.6−2-fold higher than that of 38 against HeLa cells. The 3′- and 4′derivatives 52−59 showed comparable activity to 38 against both cells except for 4′-hydroxy derivative 56 and 4′-methoxy derivative 57, which were 1.6-fold more potent than 38 against HL-60 cells. The presence of substituent on 2′-position of 7-(3hydroxy-4-methoxyphenyl)-7′-aryl derivatives was important for the higher activity. 7-(3-Hydroxy-4-methoxyphenyl)-7′-(2′-
of the aromatic ring on the activity was examined. Table 2 shows the activities of 7-derivatives of (8R,8′R)-DGA. Without a substituent on the 7-aromatic ring, derivative 16 showed 2.6fold higher activity than (8R,8′R)-DGA (3) against HL-60 cells and similar activity to 3 against HeLa cells. It could be assumed that the 3-methoxy group and 4-hydroxy group of 3 do not play an important role to keep 10−30 μM of IC50 values. As for 2substituted derivatives 17−22, all derivatives showed 2−4-fold higher activity than that of (8R,8′R)-DGA (3) against HL-60 cells. The activities of 2-methoxy derivative 18, 2-butoxy derivative 19, and 2-methyl derivative 20 bearing an electron donor group were about 2-fold higher than those of hydrophilic 2-hydroxy derivative 17 and 2-halo derivative 21 and 22 bearing an electron-withdrawing group, suggesting that the hydrophobic and electron donor substituents on the 2-position are favorable for higher activity against HL-60 cells. Because the activity of 2-butoxy derivative 19 was similar to that of 2methoxy derivative 18 against HL-60 cells, the length of alkoxy group would not affect the activity. Against HeLa cells, hydrophilic 2-hydroxy derivative 17 and 2-butoxy derivative 19 bearing a longer alkoxy group exhibited 2-fold higher activity than that of (8R,8′R)-DGA (3). On the other hand, the same level of activities as that of (8R,8′R)-DGA (3) were observed in 2-methoxy derivative 18, 2-methyl derivative 20, and 2-halo derivative 21 and 22. The 2-hydroxy derivative 17 and 2-butoxy derivative 19 showed higher activity than (8R,8′R)-DGA (3) against both cells. The effect of 3-substituent was also examined. It was shown that the activities of 3-hydroxy derivative 23 and 3-methoxy derivative 24 were similar to that of (8R,8′R)-DGA (3) against both HL-60 and HeLa cells. The more hydrophobic derivatives, 3-butoxy derivative 25, 3-methyl derivative 26, 3-fluoro derivative 27, and 3-chloro derivative 28 were 2−3-fold more effective than (8R,8′R)-DGA (3) against HL-60 cells. Against HeLa cells, the activity level of 3-methyl derivative 26, 3-fluoro derivative 27, and 3-chloro derivative 28 was almost the same as that of (8R,8′R)-DGA (3); however, 3butoxy derivative 25 exhibited 2-fold more potent activity than (8R,8′R)-DGA (3). The 3-butoxy derivative 25 bearing a longer and hydrophobic group displayed the highest activity among the 3-substituted derivatives against both cells. In the case of the 4-position, 4-hydroxy derivative 29 and 4-butoxy derivative 31 were 4-fold more potent and 4-methoxy derivative 30 and 4-halide derivative 33 and 34 were 2-fold more potent than that of (8R,8′R)-DGA (3) against HL-60 cells. Against HeLa cells, 2-fold higher activities than that of (8R,8′R)-DGA (3) were observed in 4-hydroxy derivative 29 and 4-butoxy derivative 31. The activities of 4-methyl derivative 32 against HL-60 and HeLa cells and 4-methoxy derivative 30 and 4halide derivative 33 and 34 against HeLa cells were similar to that of (8R,8′R)-DGA (3). The phenolic derivative and longer alkoxy derivative were more effective at the 4-position as well as the 2-position against both cells. The activities of all monosubstituted derivatives are not less potent than that of (8R,8′R)-DGA (3). Especially, the IC50 values of 2-hydroxy derivative 17 and 2-butoxy derivative 19 were less than 10 μM against both HL-60 and HeLa cells. The activities of disubstituted compounds 35−40 were also compared. The 3,4-dihydroxy derivative 35 was 5-fold more potent against HL60 cells and 2-fold more potent against HeLa cells than 3,4dimethoxy derivative 37 and 3,4-methylenedioxy derivative 40, whose activities were similar to that of (8R,8′R)-DGA (3). The 3,5-dihydroxy derivative 36 showed 3-fold and 4-fold higher activity against HL-60 cells and HeLa cells, respectively, than 5313
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Funding
ethoxyphenyl) derivative 47 showed the most potent activity against both cells in this research. The shorter and longer alkoxy group at the 2′-position decreased activity (Table 3). Cytotoxic Activity against Colon 26 and Vero Cells. Finally, the natural (8R,8′R)-DGA (3) and the higher active derivatives 38 and 47 against HL-60 and HeLa cells were applied to cytotoxic assay against colon 26 as colorectal cancer cells and Vero cells as normal cells (Table 4). Although the activities against colon 26 cells were weaker than against HL-60 and HeLa cells, these derivatives were also effective. Especially, the IC50 value of compounds 47 against colon 26 was less than 10 μM. Theses derivatives were also effective against Vero cells; however, their activities were weaker than against HL-60 and HeLa cells. The activity of derivative 38 was 3-fold less active, and derivative 47 showed 4−8.5-fold less activity against Vero cells than against HL-60 and HeLa cells, respectively. The most specific activity against cancer cells was observed in derivative 47. In conclusion, we clarified the structure-cytotoxic activity relationship of butane-type lignan containing dietary lignan, secoisolariciresinol, for the first time. The hydroxy groups on 9and 9′-positions of secoisolariciresinol are disadvantageous for the activity. This fact was confirmed by the appearance of activity of 9- and 9′-reductive type lignan, dihydroguaiaretic acid (DGA), whose all stereoisomers showed same level of activities. In the course of the evaluation of activities of the derivatives, 9-butyl (8R,8′R)-DGA derivative 13, 7-(2-hydroxyphenyl) (8R,8′R)-DGA derivative 17, 7-(2-butoxyphenyl) (8R,8′R)- DGA derivative 19, 7-(3,5-dimethoxy-4-hydroxy (8R,8′R)-DGA derivative 41, and 7-(3-hydroxy-4-methoxyphenyl) (8R,8′R)-DGA derivative 38 showed 2−4-fold higher activity than (8R,8′R)-DGA (3). Finally, 7-(3-hydroxy-4methoxyphenyl)-7′-(2′-ethoxyphenyl) DGA derivative 47 showed highest cytotoxic activity in this research, showing 32-fold and 13-fold higher activity against HL-60 cells (IC50 = 0.8 μM) and HeLa cells (IC50 = 1.7 μM), respectively, than (8R,8′R)-DGA (3). This derivative 47 was also effective against colon 26 cells. Although (8R,8′R)-9,9′-anhydrosecoisolariciresinol (2), which is a candidate for metabolite of dietary secoisolariciresinol, did not show the cytotoxic activity in this research, the higher cytotoxic active dihydroguaiaretic acid (DGA) derivative was prepared as a new lead compound, whose main chemical structure is same as that of dietary secoisolariciresinol. Since there is a possibility that dietary lignan derivatives will be detected as a metabolite, the study on structure−activity relationship of lignan should be promoted to examine the effect of dietary lignan on health and safety. This result would contribute to development of newer lead compounds of medicine based on natural dietary compounds.
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We are grateful to Marutomo Co. for financial support. Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS Part of this study was performed at INCS (Johoku station) of Ehime University. Our thanks to the president of Ehime University for supporting this project.
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ASSOCIATED CONTENT
S Supporting Information *
Supplementary data includes melting points and both NMR and MS data for investigated compounds. Supporting Information also includes additional details for compound syntheses. This material is available free of charge via the Internet at http://pubs.acs.org.
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