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Journal of Asian Natural Products Research Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/ganp20
A new lignan glycoside from Trigonostemon heterophyllus ab
ac
ac
ac
Yi-Xing Li , Wen-Jian Zuo , Xiao-Na Li , Wen-Li Mei
& Hao-Fu
ac
Dai a
Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China b
Click for updates
Haikou Experimental Station, Chinese Academy of Tropical Agricultural Sciences, Haikou 570102, China c
Hainan Key Laboratory for Research and Development of Natural Product from Li Folk Medicine, Haikou 571101, China Published online: 02 May 2014.
To cite this article: Yi-Xing Li, Wen-Jian Zuo, Xiao-Na Li, Wen-Li Mei & Hao-Fu Dai (2014) A new lignan glycoside from Trigonostemon heterophyllus, Journal of Asian Natural Products Research, 16:5, 549-553, DOI: 10.1080/10286020.2014.914503 To link to this article: http://dx.doi.org/10.1080/10286020.2014.914503
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
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Journal of Asian Natural Products Research, 2014 Vol. 16, No. 5, 549–553, http://dx.doi.org/10.1080/10286020.2014.914503
A new lignan glycoside from Trigonostemon heterophyllus Yi-Xing Liab, Wen-Jian Zuoac, Xiao-Na Liac, Wen-Li Meiac* and Hao-Fu Daiac* a Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China; bHaikou Experimental Station, Chinese Academy of Tropical Agricultural Sciences, Haikou 570102, China; cHainan Key Laboratory for Research and Development of Natural Product from Li Folk Medicine, Haikou 571101, China
Downloaded by [Florida State University] at 16:08 19 December 2014
(Received 8 April 2014; final version received 9 April 2014) Phytochemical investigation on the stems of Trigonostemon heterophyllus led to the isolation of a new lariciresinol-based lignan glycoside, trigonoheteran (1), together with a known lignan glycoside, aviculin (2). Their structures were elucidated by spectroscopic methods including 1D and 2D NMR (HMQC, 1H– 1H COSY, HMBC, and NOESY). Keywords: Euphorbiaceae; Trigonostemon heterophyllus; lignan glycoside; trigonoheteran
1.
Introduction
The genus Trigonostemon (Euphorbiaceae) comprising approximately 50 species grows mainly in the tropical and subtropical regions of Asia [1]. Trigonostemon reidioides has been used in Thai medicine as an antidote, expectorant, and laxative agent. Previous chemical investigations on this genus have led to the isolation of a number of structurally interesting compounds such as 38 modified daphnane diterpenoids [2 –13], phenanthrenes [11,14,15], and carboline alkaloids [16]. In addition, daphnane diterpenoids are known to have various bioactivities, such as anti-HIV-1 [9] and cytotoxic [5] activities. In our previous screening for cytotoxic agents from tropical medicinal plants, a new diterpenoid and a new naphthoquinone [17] have been isolated from Trigonostemon heterophyllus collected in Hainan Province of China. Yue et al. reported that five new daphnane diterpenoids, a new 3,4-secocleistanthane dinorditerpenoid, and a new
prenylated bisabolane sesquiterpenoid [13] were isolated from the same species. Our continued study on the chemical constituents from T. heterophyllus led to the isolation of a new lariciresinol-based lignan glycoside, trigonoheteran (1), and a known lignan glycoside, aviculin (2) (Figure 1). This paper describes the isolation and structural elucidation of the new compound. 2.
Results and discussion
Trigonoheteran (1) was obtained as white powder. The molecular formula was deduced as C35H42O15 on the basis of the HR-ESI-MS at m/z 725.2401 [M þ Na]þ, which indicated 15 degrees of unsaturation. The IR spectrum showed absorptions for hydroxyl group (3570, 3292 cm21), a conjugated-ester carbonyl group (1709 cm21) and aromatic ring (1597, 1514, and 1464 cm21). The 1H NMR spectrum (Table 1) of 1 clearly showed the presence of two ABX patterns including the protons at d 6.45 (1H, dd, J ¼ 8.5,
*Corresponding authors. Email: [email protected]; [email protected] q 2014 Taylor & Francis
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Y.-X. Li et al. 2' 3' 9' 8'
H3CO
O 6''' H3CO 5''' 1''' C
OH
7' 1'
3 2 O
4 6'' O 7''' O 5'' 5 O 2''' HO 4''' 3''' 4'' OH 1'' 3'' OCH3 2''
OCH3
7 8
9
4' 6'
OH
5'
OH
1 6
OH
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Figure 1. The structure of compound 1.
Table 1.
1
H (500 MHz) and 13C (125 MHz) NMR spectral data of 1 in DMSO-d6.
Position
dC
1 2 3 4 5 6 7 8 9
139.6 s 111.5 d 150.8 s 147.1 s 118.1 d 119.3 d 83.6 d 54.0 d 60.5 t
3-OCH3 10 20 30 40 50 60 70
56.8 q 133.6 s 113.5 d 149.0 s 145.8 s 116.2 d 122.2 d 33.6 t
80 90
43.7 d 73.6 t
30 -OCH3 100 200 300 400 500 600
56.5 q 103.1 d 74.9 d 77.8 d 72.1 d 75.6 d 65.2 t
1000 2000 ,6000 3000 ,5000 4000 7000 3000 ,5000 -OCH3
121.1 s 108.5 d 149.0 s 142.4 s 167.8 s 57.0 q
dH (J in Hz)
HMBC (H to C)
6.90 (1H, d, J ¼ 1.5)
C-7, C-6, C-1, C-3, C-4
6.99 (1H, d, J ¼ 8.5) 6.45 (1H, dd, J ¼ 8.5, 1.5) 4.69 (1H, d, J ¼ 6.5) 2.23 (1H, m) 3.78 (1H, overlapped), 3.56 (1H, overlapped) 3.80 (3H, s)
C-1, C-3, C-4 C-1, C-2, C-4 C-8, C-9, C-80 , C-1, C-2 C-1, C-70 , C-90 , C-7, C-80 C-7, C-80 , C-8
6.77 (1H, d, J ¼ 1.8)
C-10 , C-30 , C-40 , C-60 , C-70
6.69 (1H, d, J ¼ 8.0) 6.61 (1H, dd, J ¼ 8.0, 1.8) 2.88 (1H, dd, J ¼ 13.0, 11.0), 2.46 (1H, dd, J ¼ 13.0, 4.2) 2.65 (1H, m) 3.93 (1H, t, J ¼ 8.0), 3.68 (1H, t, J ¼ 8.0) 3.80 (3H, s) 4.83 (1H, d, J ¼ 8.2) 3.50 (1H, overlapped) 3.51 (1H, overlapped) 3.38 (1H, overlapped) 3.76 (1H, overlapped) 4.63 (1H, dd, J ¼ 12.0, 2.5), 4.45 (1H, dd, J ¼ 12.0, 7.5)
C-10 , C-30 , C-40 C-20 , C-70 , C-40 C-80 , C-20 , C-60 , C-10 , C-90
C-3
C-8, C-7, C-90 , C-9, C-70 C-70 , C-80 , C-8 C-30 C-4, C-200 C-100 , C-300 C-200 , C-400 C-300 , C-500 C-400 , C-600 C-7000 , C-500
7.33 (2H, s)
C-7000 , C-3000 , C-5000 , C-4000
3.82 (6H, s)
C-3000 , C-5000
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OCH3 OH O C
H3CO
H3CO
O OH
O
O O
HO
OH OCH3 1
OH
HMBC 1H-1HCOSY
OH
1
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Figure 2. Key HMBC and H – H COSY correlations of compound 1.
1.5 Hz), 6.90 (1H, d, J ¼ 1.5 Hz), and 6.99 (1H, d, J ¼ 8.5 Hz), and 6.61 (1H, dd, J ¼ 8.0, 1.8 Hz), 6.69 (1H, d, J ¼ 8.0 Hz), and 6.77 (1H, d, J ¼ 1.8 Hz), and two methoxyl signals at d 3.80 (6H, s). The 1H NMR spectrum of 1 also disclosed a diarylepoxylignan skeleton characterized by the presence of one downfield-shifted benzylic CH signal at d 4.69 (1H, d, J ¼ 6.5 Hz), benzylic CH2 signals at d 2.88 (1H, dd, J ¼ 13.0, 11.0 Hz) and 2.46 (1H, dd, J ¼ 13.0, 4.2 Hz), and CH2OH signals (d 3.78 and 3.56, each 1H, overlapping with other signals). In addition, proton signals belonging to a glucose unit were also observed at d 4.83 –3.38. The glucose group was assigned at C-4 position by the HMBC correlations from H-100 to C-4 (Figure 2). The J value (8.2 Hz) of the anomeric H-atom and HPLC analysis of the acidic hydrolysate compared with authentic D -glucose (column: Waters Xbridge Amide, 100 mm £ 4.6 mm, 3.5 mm; column temperature: 308C; mobile phase: acetonitrile –water ¼ 40:60 (v/v) with 0.2% TEA; flow rate: 1.0 ml/ min; detector: refractive index; identification of D -glucose was carried out by comparison of these retention times and optical rotations with authentic D -glucose: tR ¼ 5.5 min) established the b-D -configuration of the glucose moiety. From above data, the structure of 1 was similar to that of lariciresinol 4-O-b-D -glucopyranoside [18] except that 1 showed the presence of an additional syringoyl moiety [dH 7.33 (2H, s), 3.82 (6H, s); dC 121.2 (C-
1000 ), 108.5 (C-2000 , 5000 ), 149.0 (C-3000 , 5000 ), 142.4 (C-4 000 ), 167.8 (C-7 000 ), 57.0 (2CH3O)] attached to C-600 by the HMBC correlations from Ha-600 and Hb-600 to C-7000 (Figure 2). Furthermore, for the relative configurations, the trans-configuration between the methine protons at C-7 and C-8 was established by the coupling constant of H7 (1H, d, J ¼ 6.5 Hz) [19], and the cisconfiguration between the methine protons at H-8 and H-80 was established by the ROESY correlations of H2-9 with H2-70 . Therefore, compound 1 was assigned as lariciresinol 4-O-(6-O-syringoyl)-b-D -glucopyranoside, and named trigonoheteran. The known compound aviculin (2) was identified by comparison of its spectral data (1H and 13C NMR) with those reported in the literature. 3. 3.1
Experimental General experimental procedures
Optical rotation was recorded using a Rudolph Autopol III polarimeter (Rudolph Research Analytical, Hackettstown, NJ, USA). The UV spectra were measured on a Shimadzu UV-2550 spectrometer (Beckman, Brea, CA, USA). The IR spectra were obtained on a Nicolet 380 FT-IR instrument from KBr pellets (Thermo, Pittsburgh, PA, USA). The NMR spectra were recorded on a Bruker AV-500 spectrometer, using TMS (tetramethylsilane) as an internal standard (Bruker, Bremen, Germany). The HR-ESI-MS
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Y.-X. Li et al.
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were measured with an API QSTAR Pulsar mass spectrometer (Bruker). Column chromatography (CC) was carried out with silica gel (Marine Chemical Industry Factory, Qingdao, China), Sephadex LH-20 (Merck, Darmstadt, Germany), and RP-18 (Merck). TLC was carried out with silica gel GF254 (Marine Chemical Industry Factory). 3.2 Plant material The stems of T. heterophyllus were collected in Boating county, Hainan Province, China (March 2009), and authenticated by Associate Professor Zheng-Fu Dai of the Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, where a voucher specimen (No. A20090303) is deposited.
Fraction 6 (4.24 g) was subjected to RP-18, eluting with MeOH – H2O (10:1 to 5:1, v/v) to give seven fractions (6.1 –6.7). Fraction 6.6 (0.6 g) was submitted to Sephadex LH-20, eluting with CHCl3 – MeOH (1:1, v/v) to afford four fractions (6.6.1 – 6.6.4). Fraction 6.6.2 (82.0 mg) was purified by RP-18, with MeOH – H2O (3:7 to 5:5, v/v) as eluent to give 2 (13.0 mg). 3.3.1
Trigonoheteran (1)
White powder; ½a22 D 2 50.0 (c ¼ 0.02, MeOH); UV (MeOH) lmax: 219, 228, 278 nm; IR (KBr) nmax: 3570, 3292, 1709, 1597, 1514, 1464 cm21; for 1H and 13C NMR spectral data, see Table 1; HR-ESIMS: m/z 725.2401[M þ Na]þ (calcd for C35H42O15Na, 725.2421). Acknowledgments
3.3 Extraction and isolation The stems of T. heterophyllus (dry weight 15.0 kg) were extracted three times with 95% EtOH at room temperature. The extract was evaporated under reduced pressure to dryness. Then, the residue was suspended in H2O and partitioned with petroleum ether, EtOAc, and then nBuOH. The EtOAc fraction (58.0 g) was separated into seven fractions on a silica gel column using a step gradient elution of CHCl3 – MeOH (50:1 to 0:1, v/v). Fraction 4 (3.8 g) was submitted to Sephadex LH-20, eluting with CHCl3 – MeOH (1:1, v/v) to afford three fractions (4.1 – 4.3). Fraction 4.2 (1.5 g) was subjected to CC, with CHCl3 – MeOH (30:1 to 2:1, v/v) as eluent, to afford eight fractions (4.2.1– 4.2.8). Fraction 4.2.6 was subjected to CC, eluting with CHCl3 – MeOH (9:1, v/v) to afford four fractions (4.2.6.1– 4.2.6.4). Fraction 4.2.6.3 was applied to Sephadex LH-20, eluting with CHCl3 – MeOH (1:1, v/v), then RP-18 with MeOH – H2O (10:11, v/v) as eluent, to give 1 (8.0 mg).
This research was financially supported by Special Fund for Agro-scientific Research in the Public Interest (201303117), National Support Science and Technology Subject (2013BAI11B04), and Major Technology Project of Hainan Province (ZDZX2013008-4).
References [1] S.K. Chen, B.Y. Chen, and H. Li, Flora of China (Science Press, Beijing, 1997), Vol. 44, p. 162. [2] A. Tempeam, N. Thasana, A. Dawornkricharut, C. Pavaro, and S. Ruchirawat, Mahidol U. J. Pharm. Sci. 29, 25 (2002). [3] H. Jayasuriya, D.L. Zink, R.P. Borris, W. Nanakorn, H.T. Beck, M.J. Balick, M.A. Goetz, L. Gregory, W.L. Shoop, and S.B. Singh, J. Nat. Prod. 67, 228 (2004). [4] A. Tempeam, N. Thasana, C. Pavaro, W. Chuakul, P. Siripong, and S. Ruchirawat, Chem. Pharm. Bull. 53, 1321 (2005). [5] N. Soonthornchareonnon, M. Sakayarojkul, M. Isaka, V. Mahakittikun, C.W. huakul, and P. Wongsinkongman, Chem. Pharm. Bull. 53, 241 (2005). [6] H.D. Chen, X.F. He, J. Ai, M.Y. Geng, and J.M. Yue, Org. Lett. 11, 4080 (2009). [7] H.D. Chen, S.P. Yang, X.F. He, J. Ai, Z.K. Liu, H.B. Liu, M.Y. Geng, and J.M. Yue, Org. Lett. 12, 1168 (2010).
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Journal of Asian Natural Products Research [8] H.D. Chen, S.P. Yang, X.F. He, H.B. Liu, J. Ding, and J.M. Yue, Tetrahedron 66, 5065 (2010). [9] L. Zhang, R.H. Luo, F. Wang, Z.J. Dong, L.M. Yang, Y.T. Zheng, and J.K. Liu, Phytochemistry 71, 1879 (2010). [10] L. Zhang, R.H. Luo, F. Wang, M.Y. Jiang, Z.J. Dong, L.M. Yang, Y.T. Zheng, and J.K. Liu, Org. Lett. 12, 152 (2010). [11] B.D. Lin, M.L. Han, Y.C. Ji, H.D. Chen, S.P. Yang, S. Zhang, M.Y. Geng, and J.M. Yue, J. Nat. Prod. 73, 1301 (2010). [12] S.F. Li, Y.T. Di, S. Li, Y. Zhang, F.M. Yang, Q.Y. Sun, J.M. Simo, H.P. He, and X.J. Hao, J. Nat. Prod. 74, 464 (2011). [13] S.H. Dong, H.B. Liu, C.H. Xu, J. Ding, and J.M. Yue, J. Nat. Prod. 74, 2576 (2011).
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[14] X.J. Hu, Y.H. Wang, L.Y. Kong, H.P. He, S. Gao, H.Y. Liu, J. Ding, H. Xie, Y.T. Di, and X.J. Hao, Tetrahedron Lett. 50, 2917 (2009). [15] S. Yin, Z.S. Su, Z.W. Zhou, L. Dong, and J.M. Yue, J. Nat. Prod. 71, 1414 (2008). [16] X.J. Hu, Y.D. Di, Y.H. Wang, L.Y. Kong, S. Gao, C.S. Li, H.Y. Liu, H.P. He, J. Ding, H. Xie, and X.J. Hao, Planta Med. 75, 1157 (2009). [17] Y.X. Li, W.L. Mei, W.J. Zuo, Y.X. Zhao, W.H. Dong, and H.F. Dai, Phytochem. Lett. 5, 41 (2012). [18] M. Sugiyama and M. Kikuchi, Heterocycles. 36, 117 (1993). [19] H.J. Km, E.R. Woo, and H. Park, J. Nat. Prod. 57, 581 (1994).
Journal of Asian Natural Products Research Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/ganp20
A new lignan glycoside from Trigonostemon heterophyllus ab
ac
ac
ac
Yi-Xing Li , Wen-Jian Zuo , Xiao-Na Li , Wen-Li Mei
& Hao-Fu
ac
Dai a
Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China b
Click for updates
Haikou Experimental Station, Chinese Academy of Tropical Agricultural Sciences, Haikou 570102, China c
Hainan Key Laboratory for Research and Development of Natural Product from Li Folk Medicine, Haikou 571101, China Published online: 02 May 2014.
To cite this article: Yi-Xing Li, Wen-Jian Zuo, Xiao-Na Li, Wen-Li Mei & Hao-Fu Dai (2014) A new lignan glycoside from Trigonostemon heterophyllus, Journal of Asian Natural Products Research, 16:5, 549-553, DOI: 10.1080/10286020.2014.914503 To link to this article: http://dx.doi.org/10.1080/10286020.2014.914503
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
Downloaded by [Florida State University] at 16:08 19 December 2014
systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/termsand-conditions
Journal of Asian Natural Products Research, 2014 Vol. 16, No. 5, 549–553, http://dx.doi.org/10.1080/10286020.2014.914503
A new lignan glycoside from Trigonostemon heterophyllus Yi-Xing Liab, Wen-Jian Zuoac, Xiao-Na Liac, Wen-Li Meiac* and Hao-Fu Daiac* a Key Laboratory of Tropical Crop Biotechnology, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China; bHaikou Experimental Station, Chinese Academy of Tropical Agricultural Sciences, Haikou 570102, China; cHainan Key Laboratory for Research and Development of Natural Product from Li Folk Medicine, Haikou 571101, China
Downloaded by [Florida State University] at 16:08 19 December 2014
(Received 8 April 2014; final version received 9 April 2014) Phytochemical investigation on the stems of Trigonostemon heterophyllus led to the isolation of a new lariciresinol-based lignan glycoside, trigonoheteran (1), together with a known lignan glycoside, aviculin (2). Their structures were elucidated by spectroscopic methods including 1D and 2D NMR (HMQC, 1H– 1H COSY, HMBC, and NOESY). Keywords: Euphorbiaceae; Trigonostemon heterophyllus; lignan glycoside; trigonoheteran
1.
Introduction
The genus Trigonostemon (Euphorbiaceae) comprising approximately 50 species grows mainly in the tropical and subtropical regions of Asia [1]. Trigonostemon reidioides has been used in Thai medicine as an antidote, expectorant, and laxative agent. Previous chemical investigations on this genus have led to the isolation of a number of structurally interesting compounds such as 38 modified daphnane diterpenoids [2 –13], phenanthrenes [11,14,15], and carboline alkaloids [16]. In addition, daphnane diterpenoids are known to have various bioactivities, such as anti-HIV-1 [9] and cytotoxic [5] activities. In our previous screening for cytotoxic agents from tropical medicinal plants, a new diterpenoid and a new naphthoquinone [17] have been isolated from Trigonostemon heterophyllus collected in Hainan Province of China. Yue et al. reported that five new daphnane diterpenoids, a new 3,4-secocleistanthane dinorditerpenoid, and a new
prenylated bisabolane sesquiterpenoid [13] were isolated from the same species. Our continued study on the chemical constituents from T. heterophyllus led to the isolation of a new lariciresinol-based lignan glycoside, trigonoheteran (1), and a known lignan glycoside, aviculin (2) (Figure 1). This paper describes the isolation and structural elucidation of the new compound. 2.
Results and discussion
Trigonoheteran (1) was obtained as white powder. The molecular formula was deduced as C35H42O15 on the basis of the HR-ESI-MS at m/z 725.2401 [M þ Na]þ, which indicated 15 degrees of unsaturation. The IR spectrum showed absorptions for hydroxyl group (3570, 3292 cm21), a conjugated-ester carbonyl group (1709 cm21) and aromatic ring (1597, 1514, and 1464 cm21). The 1H NMR spectrum (Table 1) of 1 clearly showed the presence of two ABX patterns including the protons at d 6.45 (1H, dd, J ¼ 8.5,
*Corresponding authors. Email: [email protected]; [email protected] q 2014 Taylor & Francis
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Y.-X. Li et al. 2' 3' 9' 8'
H3CO
O 6''' H3CO 5''' 1''' C
OH
7' 1'
3 2 O
4 6'' O 7''' O 5'' 5 O 2''' HO 4''' 3''' 4'' OH 1'' 3'' OCH3 2''
OCH3
7 8
9
4' 6'
OH
5'
OH
1 6
OH
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Figure 1. The structure of compound 1.
Table 1.
1
H (500 MHz) and 13C (125 MHz) NMR spectral data of 1 in DMSO-d6.
Position
dC
1 2 3 4 5 6 7 8 9
139.6 s 111.5 d 150.8 s 147.1 s 118.1 d 119.3 d 83.6 d 54.0 d 60.5 t
3-OCH3 10 20 30 40 50 60 70
56.8 q 133.6 s 113.5 d 149.0 s 145.8 s 116.2 d 122.2 d 33.6 t
80 90
43.7 d 73.6 t
30 -OCH3 100 200 300 400 500 600
56.5 q 103.1 d 74.9 d 77.8 d 72.1 d 75.6 d 65.2 t
1000 2000 ,6000 3000 ,5000 4000 7000 3000 ,5000 -OCH3
121.1 s 108.5 d 149.0 s 142.4 s 167.8 s 57.0 q
dH (J in Hz)
HMBC (H to C)
6.90 (1H, d, J ¼ 1.5)
C-7, C-6, C-1, C-3, C-4
6.99 (1H, d, J ¼ 8.5) 6.45 (1H, dd, J ¼ 8.5, 1.5) 4.69 (1H, d, J ¼ 6.5) 2.23 (1H, m) 3.78 (1H, overlapped), 3.56 (1H, overlapped) 3.80 (3H, s)
C-1, C-3, C-4 C-1, C-2, C-4 C-8, C-9, C-80 , C-1, C-2 C-1, C-70 , C-90 , C-7, C-80 C-7, C-80 , C-8
6.77 (1H, d, J ¼ 1.8)
C-10 , C-30 , C-40 , C-60 , C-70
6.69 (1H, d, J ¼ 8.0) 6.61 (1H, dd, J ¼ 8.0, 1.8) 2.88 (1H, dd, J ¼ 13.0, 11.0), 2.46 (1H, dd, J ¼ 13.0, 4.2) 2.65 (1H, m) 3.93 (1H, t, J ¼ 8.0), 3.68 (1H, t, J ¼ 8.0) 3.80 (3H, s) 4.83 (1H, d, J ¼ 8.2) 3.50 (1H, overlapped) 3.51 (1H, overlapped) 3.38 (1H, overlapped) 3.76 (1H, overlapped) 4.63 (1H, dd, J ¼ 12.0, 2.5), 4.45 (1H, dd, J ¼ 12.0, 7.5)
C-10 , C-30 , C-40 C-20 , C-70 , C-40 C-80 , C-20 , C-60 , C-10 , C-90
C-3
C-8, C-7, C-90 , C-9, C-70 C-70 , C-80 , C-8 C-30 C-4, C-200 C-100 , C-300 C-200 , C-400 C-300 , C-500 C-400 , C-600 C-7000 , C-500
7.33 (2H, s)
C-7000 , C-3000 , C-5000 , C-4000
3.82 (6H, s)
C-3000 , C-5000
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OCH3 OH O C
H3CO
H3CO
O OH
O
O O
HO
OH OCH3 1
OH
HMBC 1H-1HCOSY
OH
1
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Figure 2. Key HMBC and H – H COSY correlations of compound 1.
1.5 Hz), 6.90 (1H, d, J ¼ 1.5 Hz), and 6.99 (1H, d, J ¼ 8.5 Hz), and 6.61 (1H, dd, J ¼ 8.0, 1.8 Hz), 6.69 (1H, d, J ¼ 8.0 Hz), and 6.77 (1H, d, J ¼ 1.8 Hz), and two methoxyl signals at d 3.80 (6H, s). The 1H NMR spectrum of 1 also disclosed a diarylepoxylignan skeleton characterized by the presence of one downfield-shifted benzylic CH signal at d 4.69 (1H, d, J ¼ 6.5 Hz), benzylic CH2 signals at d 2.88 (1H, dd, J ¼ 13.0, 11.0 Hz) and 2.46 (1H, dd, J ¼ 13.0, 4.2 Hz), and CH2OH signals (d 3.78 and 3.56, each 1H, overlapping with other signals). In addition, proton signals belonging to a glucose unit were also observed at d 4.83 –3.38. The glucose group was assigned at C-4 position by the HMBC correlations from H-100 to C-4 (Figure 2). The J value (8.2 Hz) of the anomeric H-atom and HPLC analysis of the acidic hydrolysate compared with authentic D -glucose (column: Waters Xbridge Amide, 100 mm £ 4.6 mm, 3.5 mm; column temperature: 308C; mobile phase: acetonitrile –water ¼ 40:60 (v/v) with 0.2% TEA; flow rate: 1.0 ml/ min; detector: refractive index; identification of D -glucose was carried out by comparison of these retention times and optical rotations with authentic D -glucose: tR ¼ 5.5 min) established the b-D -configuration of the glucose moiety. From above data, the structure of 1 was similar to that of lariciresinol 4-O-b-D -glucopyranoside [18] except that 1 showed the presence of an additional syringoyl moiety [dH 7.33 (2H, s), 3.82 (6H, s); dC 121.2 (C-
1000 ), 108.5 (C-2000 , 5000 ), 149.0 (C-3000 , 5000 ), 142.4 (C-4 000 ), 167.8 (C-7 000 ), 57.0 (2CH3O)] attached to C-600 by the HMBC correlations from Ha-600 and Hb-600 to C-7000 (Figure 2). Furthermore, for the relative configurations, the trans-configuration between the methine protons at C-7 and C-8 was established by the coupling constant of H7 (1H, d, J ¼ 6.5 Hz) [19], and the cisconfiguration between the methine protons at H-8 and H-80 was established by the ROESY correlations of H2-9 with H2-70 . Therefore, compound 1 was assigned as lariciresinol 4-O-(6-O-syringoyl)-b-D -glucopyranoside, and named trigonoheteran. The known compound aviculin (2) was identified by comparison of its spectral data (1H and 13C NMR) with those reported in the literature. 3. 3.1
Experimental General experimental procedures
Optical rotation was recorded using a Rudolph Autopol III polarimeter (Rudolph Research Analytical, Hackettstown, NJ, USA). The UV spectra were measured on a Shimadzu UV-2550 spectrometer (Beckman, Brea, CA, USA). The IR spectra were obtained on a Nicolet 380 FT-IR instrument from KBr pellets (Thermo, Pittsburgh, PA, USA). The NMR spectra were recorded on a Bruker AV-500 spectrometer, using TMS (tetramethylsilane) as an internal standard (Bruker, Bremen, Germany). The HR-ESI-MS
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were measured with an API QSTAR Pulsar mass spectrometer (Bruker). Column chromatography (CC) was carried out with silica gel (Marine Chemical Industry Factory, Qingdao, China), Sephadex LH-20 (Merck, Darmstadt, Germany), and RP-18 (Merck). TLC was carried out with silica gel GF254 (Marine Chemical Industry Factory). 3.2 Plant material The stems of T. heterophyllus were collected in Boating county, Hainan Province, China (March 2009), and authenticated by Associate Professor Zheng-Fu Dai of the Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Science, where a voucher specimen (No. A20090303) is deposited.
Fraction 6 (4.24 g) was subjected to RP-18, eluting with MeOH – H2O (10:1 to 5:1, v/v) to give seven fractions (6.1 –6.7). Fraction 6.6 (0.6 g) was submitted to Sephadex LH-20, eluting with CHCl3 – MeOH (1:1, v/v) to afford four fractions (6.6.1 – 6.6.4). Fraction 6.6.2 (82.0 mg) was purified by RP-18, with MeOH – H2O (3:7 to 5:5, v/v) as eluent to give 2 (13.0 mg). 3.3.1
Trigonoheteran (1)
White powder; ½a22 D 2 50.0 (c ¼ 0.02, MeOH); UV (MeOH) lmax: 219, 228, 278 nm; IR (KBr) nmax: 3570, 3292, 1709, 1597, 1514, 1464 cm21; for 1H and 13C NMR spectral data, see Table 1; HR-ESIMS: m/z 725.2401[M þ Na]þ (calcd for C35H42O15Na, 725.2421). Acknowledgments
3.3 Extraction and isolation The stems of T. heterophyllus (dry weight 15.0 kg) were extracted three times with 95% EtOH at room temperature. The extract was evaporated under reduced pressure to dryness. Then, the residue was suspended in H2O and partitioned with petroleum ether, EtOAc, and then nBuOH. The EtOAc fraction (58.0 g) was separated into seven fractions on a silica gel column using a step gradient elution of CHCl3 – MeOH (50:1 to 0:1, v/v). Fraction 4 (3.8 g) was submitted to Sephadex LH-20, eluting with CHCl3 – MeOH (1:1, v/v) to afford three fractions (4.1 – 4.3). Fraction 4.2 (1.5 g) was subjected to CC, with CHCl3 – MeOH (30:1 to 2:1, v/v) as eluent, to afford eight fractions (4.2.1– 4.2.8). Fraction 4.2.6 was subjected to CC, eluting with CHCl3 – MeOH (9:1, v/v) to afford four fractions (4.2.6.1– 4.2.6.4). Fraction 4.2.6.3 was applied to Sephadex LH-20, eluting with CHCl3 – MeOH (1:1, v/v), then RP-18 with MeOH – H2O (10:11, v/v) as eluent, to give 1 (8.0 mg).
This research was financially supported by Special Fund for Agro-scientific Research in the Public Interest (201303117), National Support Science and Technology Subject (2013BAI11B04), and Major Technology Project of Hainan Province (ZDZX2013008-4).
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