Letter ‐ spectral assignment Received: 22 July 2014
Revised: 28 December 2014
Accepted: 4 January 2015
Published online in Wiley Online Library: 21 May 2015
(wileyonlinelibrary.com) DOI 10.1002/mrc.4215
Structure determination of two new bisabolane-type sesquiterpenes from the rhizomes of Curcuma longa by NMR spectroscopy Jian Li,a,b Hai-Feng Wang,a,b Gang Chen,a,b Sheng-Dong Huang,a,b Wei-Yang Zhang,a,b,c Hui-Ming Huaa,b and Yue-Hu Peia,b*
Introduction Curcuma longa L. is a rhizomatous herbaceous perennial plant of the ginger family, Zingiberaceae, and has been widely cultivated and used as a traditional herbal medicine in the tropical and subtropical regions of the world.[1] A Variety of sesquiterpenoids and curcuminoids were isolated in a previous study.[2] Various biological activities, such as inhibiting carcinogenesis and cancer growth, anti-inflammatory effects, and so on, were reported.[3–5] In this study, we carried out systematic chemical research on C. longa and obtained two new bisabolane-type sesquiterpenes, together with three known sesquiterpenes, turmeronol A (3), 2-methyl6-(4-hydroxyphenyl)-2-hepten-4-one (4), and 2-methyl-6-(4-hydroxy-3-methylphenyl)-2-hepten-4-one (5). The isolation and the structural elucidation of 1 and 2 are described herein.
Results and discussion
536
Compound 1 was obtained as a colourless, viscous oil. [α] 20D +28.0 (ca 0.865, MeOH; Fig. 1). Its HRESIMS exhibited an [M + Na]+ ion at m/z 273.1453 (calcd for C15H22NaO3, 273.1467), corresponding to a molecular formula of C15H22O3. The IR spectrum of 1 displayed strong absorption bands at 3392 and 1697 cm 1, indicating the presence of hydroxyl and ketone groups respectively. The 1HNMR (400 MHz, CDCl3) spectrum (Table 1) showed three aromatic protons at δ 7.02 (1H, d, J = 7.6 Hz), 6.66 (1H, br d, J = 7.6 Hz), and 6.61 (1H, br s); four methyl group signals at δ 2.19 (3H, s), 1.23 (3H, d, J = 6.9 Hz), 1.20 (3H, s), and 1.18 (3H, s); two magnetically nonequivalent methylene proton signals at δ 2.71 (1H, dd, J = 7.0, 16.1 Hz), 2.60 (1H, dd, J = 7.3, 16.1 Hz), 2.55 (1H, d, J = 17.5 Hz), and 2.47 (1H, d, J = 17.5 Hz); and a methine proton signal at δ 3.22 (1H, m). The 13C-NMR (100 MHz, CDCl3) spectrum (Table 1) exhibited 15 carbon signals in total including a carbonyl, four methyls, two methylenes, four methines (including three sp2 carbons and one sp3 carbon), and four quaternary carbons (including two sp2 carbons, one oxygenated sp2 carbon, and one oxygenated sp3 carbon). All the carbons and the corresponding proton signals were unambiguously assigned by the HSQC and HMBC experiments. A series of key HMBC correlations were shown in Fig. 2. In addition, by comparing compound 1 with compound 3, a known bisabolane-
Magn. Reson. Chem. 2015, 53, 536–538
type sesquiterpene, the deductions in the preceding texts were verified. The 1H and 13C-NMR spectra (Table 1) of 1 were similar to those of compound 3.[6] The main differences between the spectra of 1 and 3 were the chemical shifts of C-2 and C-3 of 1; those in the spectrum of 1 were δ 70.1 and 53.6, and their counterparts in 3 were δ 153.9 and 124.1. Hence, all the aforementioned pieces of evidence characterized compound 1 as 2-hydroxy-6-(3-hydroxy-4methylphenyl)-2-methylheptan-4-one. The absolute configuration of compound 1 was determined by comparing the optical rotation value with that of a structurally similar compound turmeronol A (3) [α] 23D +63.[6] Because compound 1 showed a positive value of the specific rotation just as compound 3 did, the absolute configuration at C-6 was supposed to be S. Compound 2 was obtained as a colourless, viscous oil. [α] 20D +29.0 (ca 0.675, MeOH). Its HRESIMS exhibited an [M + Na]+ ion at m/z 287.1623 (calcd for C16H24NaO3, 287.1624), corresponding to a molecular formula of C16H24O3. The 1H-NMR (400 MHz, CDCl3) and 13C-NMR (100 MHz, CDCl3) data of 2 (Table 1) showed the presence of a methoxyl group [δ 3.18 (3H, s) and 49.3] and the same functional groups as those of 1 (Table 1), which indicated that 2 was a monomethyl ether of 1. Thus, compound 2 was elucidated as 6-(3-hydroxy-4-methylphenyl)-2-methoxy-2-methylheptan-4-one. Because it exhibited a positive value of the specific rotation, the stereostructure of 2 was supposed to be the same as that of 1. The known compounds were identified as turmeronol A (3), 2-methyl-6-(4-hydroxyphenyl)-2-hepten-4-one (4), and 2-methyl6-(4-hydroxy-3-methylphenyl)-2-hepten-4-one (5), by comparison of their physicochemical and spectroscopic properties with those reported data in the literature.[6,7]
* Correspondence to: Yue-Hu Pei, School of Traditional Chinese Materiel Medica, Shenyang Pharmaceutical University, Shenyang 110016, China. E-mail: [email protected] a Key Laboratory of Structure-Based Drug Design and Discovery, Ministry of Education, Shenyang Pharmaceutical University, Shenyang, 110016, China b School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang 110016, China c State Key Laboratory for Quality Research in Chinese Medicines, Macau University of Science and Technology, Avenida Wai Long, Taipa, Macau, China
Copyright © 2015 John Wiley & Sons, Ltd.
Bisabolane-type sesquiterpenes from the rhizomes of Curcuma longa
Figure 2. Key HMBC correlations of compounds 1–2.
Figure 1. The structures of compounds 1–5.
General experimental procedures UV spectra were recorded on a Shimadzu-2201. The IR spectrum was obtained from a Bruker IFS-55 spectrophotometer using KBr pellet. The HRESIMS data were measured on a Micromass AutoSpec UltimaE time-of-flight mass spectrophotometer. Optical rotations were determined on a PerkinElmer 241 polarimeter. Analytical HPLC was carried out on a Shimadzu LC-10AT liquid chromatography, and preparative HPLC separation was performed on a YMC-Pack ODS-A column (10 × 250 mm, 5 μm; YMC-Pack, Japan), equipped with a Shimadzu LC-8A pump and a Shimadzu SPD-10A UV–vis detector. Column chromatography was performed on silica gel G (200–300 mesh; Qingdao Haiyang Chemical Factory, Qingdao, China) and Sephadex LH-20 (Pharmacia, Piscataway, NJ, USA) columns. Thin-layer chromatography was carried out using silica gel GF254 plates, and spots were visualized by spraying with concentrated sulfuric acid–vanillin solution followed by heating.
NMR spectral methods The NMR spectra were recorded on a Bruker AVANCE-400 instrument, and the chemical shifts are given with TMS as an internal standard. The NMR experiments were carried out at 300 K with 1
the following parameters: 1H-NMR spectrum, spectrometer frequency (SF) = 400.13 MHz, spectral width (SW) = 8012.82 Hz, Fourier transform size (SI) = 65 536, acquisition time (AQ) = 4.08 s, line broadening (LB) = 0.3 Hz, relaxation delay (RD) = 1.0 s, and number of scans (NS) = 8; 13C-NMR spectrum, SF = 100.61 MHz, SW = 24 038.4 Hz, SI = 32 768, AQ = 1.36 s, LB = 1.00 Hz, RD = 2.0 s, and NS = 400 (1) or 800 (2).
Plant material The rhizomes of C. longa were purchased in Bozhou, the Anhui province of China. A voucher specimen was identified by Prof. JinCai Lu of Shenyang Pharmaceutical University and preserved in the School of Traditional Chinese Materia Medica of Shenyang Pharmaceutical University (No. 6202).
Extraction and isolation Dry rhizomes of C. longa (8 kg) were extracted by a conventional heating reflux method with 95% ethanol, and the solvent was evaporated to dryness by a vacuum rotary evaporator. Then, a crude extract (ca 590 g) was obtained. The crude extract was successively partitioned with petroleum ether, ethyl acetate, and butanol to yield three layers of extracts. Ethyl acetate layer extract (350 g) was subjected to silica gel column chromatography eluting with petroleum ether–EtOAc (100 : 0–100 : 100) to give eight fractions
13
Table 1. The H-NMR (400 MHz) and C-NMR (100 MHz) data of compounds 1–2 1 δH
No. 1′ 2′ 3′ 4′ 5′ 6′ 1 2 3
6.61 ( 1H, br s )
7.02 ( 1H, d, 7.6 ) 6.66 ( 1H, br d, 7.6 ) 1.18 ( 3H, s ) 2.55 ( 1H, d, 17.5 ) 2.47 ( 1H, d, 17.5 )
4 5
2.71 ( 1H, dd, 7.0, 16.1 ) 2.60 ( 1H, dd, 7.3, 16.1 ) 3.22 ( 1H, m ) 1.23 ( 1H, d, 6.9 ) 1.20 ( 3H, s ) 2.19 ( 3H, s )
6 7 2-CH3 4′-CH3 2-OMe 1
δC 144.9 113.5 154.3 122.1 131.1 118.5 29.3 70.1 53.6 212.6 52.7 35.1 22.1 29.2 15.5
2 HMBC
δH
C-3′, 4′, 6′, 6
6.64 ( 1H, br s )
C-1′, 3′, 4′-CH3 C-2′, 4′, 6 C-2, 3, 2-CH3
7.02 ( 1H, d, 7.6 ) 6.68 ( 1H, br d, 7.6 ) 1.17 ( 3H, s )
C-1, 2, 3, 2-CH3
2.52 (1H, d, 14.0 ) 2.46 (1H, d, 14.0 )
C-1′, 4, 6, 7
2.78 ( 1H, dd, 6.5, 16.8 ) 2.67 ( 1H, dd, 7.7, 16.8 ) 3.22 ( 1H, m ) 1.21 ( 1H, d, 6.8 ) 1.20 ( 3H, s) 2.19 ( 3H, s) 3.18 ( 3H, s)
C-1′, 2′, 6′, 4, 5, 7 C-1′, 5, 6 C-1, 2, 3 C-3′, 4′, 5′
δC
HMBC
145.7 113.6 154.1 121.7 131.1 118.7 24.9 74.5 53.2
C-1, 2, 3, 2-CH3
209.2 53.1
C-1′, 4, 6, 7
34.9 22.1 24.9 15.5 49.3
C-3′, 4′, 6
C-1′, 3′, 4′-CH3 C-2′, 4′, 6 C-2, 3, 2-CH3
C-1′, 2′, 6′, 4, 5, 7 C-1′, 5, 6 C-1, 2, 3 C-3′, 4′, 5′ C-2
13
Magn. Reson. Chem. 2015, 53, 536–538
Copyright © 2015 John Wiley & Sons, Ltd.
537
H-NMR and C-NMR recorded on ARX400 and HSQC and HMBC on AV600, in CDCl3, δ in ppm.
wileyonlinelibrary.com/journal/mrc
J. Li et al. (Fr. 1–8). Fr. 2 (12.5 g) was further separated by another silica gel column eluting with petroleum ether–EtOAc (100 : 1–100 : 100) to afford seven fractions (Fr. 2.1–2.7). Fr .2.5 was further separated by Sephadex LH-20 eluting with MeOH to obtain four fractions (Fr. 2.5.1–2.5.4). Fr. 2.5.4 was purified by preparative HPLC eluting with 52% MeOH–H2O to yield compounds 1 (29 mg, tR 30.4 min), 2 (13 mg, tR 60.1 min), and 5 (45 mg, tR 72.0 min). Fr. 2.6 was further separated by another silica gel column eluting with petroleum ether–EtOAc (100 : 1–100 : 20) to afford seven fractions (Fr. 2.6.1– 2.6.7). Fr. 2.6.2 was further separated by Sephadex LH-20 eluting with MeOH to obtain four fractions (Fr. 2.6.2.1–2.6.2.4). Fr. 2.6.2.1 was purified by preparative HPLC eluting with 50% MeOH–H2O to yield Fr. 2.6.2.1.1 and Fr. 2.6.2.1.2 (21 mg, tR 46 min). Fr. 2.6.2.1.2 was further separated by preparative thin-layer chromatograph eluting with petroleum ether–acetone (3 : 1) to yield compound 4 (10 mg, Rf = 0.24). Fr. 2.6.2.2 was purified by preparative HPLC eluting with 55% MeOH–H2O to yield compound 3 (162 mg, tR 87 min). (6S)-2-Hydroxy-6-(4-hydroxy-3-methylphenyl)-2-methylheptan4-one (1): colourless, viscous oil; [α] 20D +28.0 (ca 0.865, MeOH); UV (MeOH) λmax 203 (0.66), 214 (0.47), and 274 (0.12) nm; IR (KBr) λmax 3392, 2971, 2929, 1697, 1619, 1590, 1457, 1423, 1379, 1254, 1162, 1123, 992, 911, 811, and 639 cm 1; HRESIMS m/z 273.1453 [M + Na]+ (calcd for C15H22NaO3, 273.1467); 1H and 13 C-NMR and 2D NMR data are shown in Table 1. (6S)-6-(4-Hydroxy-3-methylphenyl)-2-methoxy-2-methylheptan4-one (2): colourless, viscous oil; [α] 20D +29.0 (ca 0.675, MeOH);
UV (MeOH) λmax 204 (0.50), 211 (0.34), and 277 (0.08); IR (KBr) λmax 3677, 3304, 2970, 2929, 1705, 1616, 1590, 1456, 1423, 1366,1254, 1186, 1121, 1074, 993, 865, 809, and 640 cm 1; HRESIMS m/z 287.1623 [M + Na]+ (calcd for C16H24NaO3, 287.1624); 1H and 13 C-NMR and 2D NMR data are shown in Table 1. Acknowledgements This paper was financially supported by Program for Innovative Research Team of the Ministry of Education and Program for Liaoning Innovative Research Team in University.
References [1] B. Sasikumar. Plant. Gen. Resour. 2005, 3, 230–251. [2] S. Li, W. Yuan, G. Deng, P. Wang, P. Yang, B. B. Aggarwal. Pharm. Crops. 2011, 2, 28–54. [3] J. J. Chen, C. S. Tsai, T. L. Hwang, P. C. Shieh. Food Chem. 2010, 119, 974–980. [4] H. Matsuda, T. Morikawa, I. Toguchida, K. Ninomiya. Chem. Pharm. Bull. 2001, 49, 1558–1566. [5] B. B. Aggarwal, W. Yuan, S. Li, S. C. Gupta. Mol. Nutr. Food Res. 2013, 57, 1529–1542. [6] I. Shinsuke, M. Maimi, F. Kazuo, H. Yoichi, S. Haruo. Agric. Biol. Cham. 1990, 54, 2367–2371. [7] Y. C. Zeng, F. Qiu, K. Yakahashi, J. M. Liang, X. S. Yao. Chem. Pharm. Bull. 2007, 55, 940–943.
538 wileyonlinelibrary.com/journal/mrc
Copyright © 2015 John Wiley & Sons, Ltd.
Magn. Reson. Chem. 2015, 53, 536–538
Revised: 28 December 2014
Accepted: 4 January 2015
Published online in Wiley Online Library: 21 May 2015
(wileyonlinelibrary.com) DOI 10.1002/mrc.4215
Structure determination of two new bisabolane-type sesquiterpenes from the rhizomes of Curcuma longa by NMR spectroscopy Jian Li,a,b Hai-Feng Wang,a,b Gang Chen,a,b Sheng-Dong Huang,a,b Wei-Yang Zhang,a,b,c Hui-Ming Huaa,b and Yue-Hu Peia,b*
Introduction Curcuma longa L. is a rhizomatous herbaceous perennial plant of the ginger family, Zingiberaceae, and has been widely cultivated and used as a traditional herbal medicine in the tropical and subtropical regions of the world.[1] A Variety of sesquiterpenoids and curcuminoids were isolated in a previous study.[2] Various biological activities, such as inhibiting carcinogenesis and cancer growth, anti-inflammatory effects, and so on, were reported.[3–5] In this study, we carried out systematic chemical research on C. longa and obtained two new bisabolane-type sesquiterpenes, together with three known sesquiterpenes, turmeronol A (3), 2-methyl6-(4-hydroxyphenyl)-2-hepten-4-one (4), and 2-methyl-6-(4-hydroxy-3-methylphenyl)-2-hepten-4-one (5). The isolation and the structural elucidation of 1 and 2 are described herein.
Results and discussion
536
Compound 1 was obtained as a colourless, viscous oil. [α] 20D +28.0 (ca 0.865, MeOH; Fig. 1). Its HRESIMS exhibited an [M + Na]+ ion at m/z 273.1453 (calcd for C15H22NaO3, 273.1467), corresponding to a molecular formula of C15H22O3. The IR spectrum of 1 displayed strong absorption bands at 3392 and 1697 cm 1, indicating the presence of hydroxyl and ketone groups respectively. The 1HNMR (400 MHz, CDCl3) spectrum (Table 1) showed three aromatic protons at δ 7.02 (1H, d, J = 7.6 Hz), 6.66 (1H, br d, J = 7.6 Hz), and 6.61 (1H, br s); four methyl group signals at δ 2.19 (3H, s), 1.23 (3H, d, J = 6.9 Hz), 1.20 (3H, s), and 1.18 (3H, s); two magnetically nonequivalent methylene proton signals at δ 2.71 (1H, dd, J = 7.0, 16.1 Hz), 2.60 (1H, dd, J = 7.3, 16.1 Hz), 2.55 (1H, d, J = 17.5 Hz), and 2.47 (1H, d, J = 17.5 Hz); and a methine proton signal at δ 3.22 (1H, m). The 13C-NMR (100 MHz, CDCl3) spectrum (Table 1) exhibited 15 carbon signals in total including a carbonyl, four methyls, two methylenes, four methines (including three sp2 carbons and one sp3 carbon), and four quaternary carbons (including two sp2 carbons, one oxygenated sp2 carbon, and one oxygenated sp3 carbon). All the carbons and the corresponding proton signals were unambiguously assigned by the HSQC and HMBC experiments. A series of key HMBC correlations were shown in Fig. 2. In addition, by comparing compound 1 with compound 3, a known bisabolane-
Magn. Reson. Chem. 2015, 53, 536–538
type sesquiterpene, the deductions in the preceding texts were verified. The 1H and 13C-NMR spectra (Table 1) of 1 were similar to those of compound 3.[6] The main differences between the spectra of 1 and 3 were the chemical shifts of C-2 and C-3 of 1; those in the spectrum of 1 were δ 70.1 and 53.6, and their counterparts in 3 were δ 153.9 and 124.1. Hence, all the aforementioned pieces of evidence characterized compound 1 as 2-hydroxy-6-(3-hydroxy-4methylphenyl)-2-methylheptan-4-one. The absolute configuration of compound 1 was determined by comparing the optical rotation value with that of a structurally similar compound turmeronol A (3) [α] 23D +63.[6] Because compound 1 showed a positive value of the specific rotation just as compound 3 did, the absolute configuration at C-6 was supposed to be S. Compound 2 was obtained as a colourless, viscous oil. [α] 20D +29.0 (ca 0.675, MeOH). Its HRESIMS exhibited an [M + Na]+ ion at m/z 287.1623 (calcd for C16H24NaO3, 287.1624), corresponding to a molecular formula of C16H24O3. The 1H-NMR (400 MHz, CDCl3) and 13C-NMR (100 MHz, CDCl3) data of 2 (Table 1) showed the presence of a methoxyl group [δ 3.18 (3H, s) and 49.3] and the same functional groups as those of 1 (Table 1), which indicated that 2 was a monomethyl ether of 1. Thus, compound 2 was elucidated as 6-(3-hydroxy-4-methylphenyl)-2-methoxy-2-methylheptan-4-one. Because it exhibited a positive value of the specific rotation, the stereostructure of 2 was supposed to be the same as that of 1. The known compounds were identified as turmeronol A (3), 2-methyl-6-(4-hydroxyphenyl)-2-hepten-4-one (4), and 2-methyl6-(4-hydroxy-3-methylphenyl)-2-hepten-4-one (5), by comparison of their physicochemical and spectroscopic properties with those reported data in the literature.[6,7]
* Correspondence to: Yue-Hu Pei, School of Traditional Chinese Materiel Medica, Shenyang Pharmaceutical University, Shenyang 110016, China. E-mail: [email protected] a Key Laboratory of Structure-Based Drug Design and Discovery, Ministry of Education, Shenyang Pharmaceutical University, Shenyang, 110016, China b School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang 110016, China c State Key Laboratory for Quality Research in Chinese Medicines, Macau University of Science and Technology, Avenida Wai Long, Taipa, Macau, China
Copyright © 2015 John Wiley & Sons, Ltd.
Bisabolane-type sesquiterpenes from the rhizomes of Curcuma longa
Figure 2. Key HMBC correlations of compounds 1–2.
Figure 1. The structures of compounds 1–5.
General experimental procedures UV spectra were recorded on a Shimadzu-2201. The IR spectrum was obtained from a Bruker IFS-55 spectrophotometer using KBr pellet. The HRESIMS data were measured on a Micromass AutoSpec UltimaE time-of-flight mass spectrophotometer. Optical rotations were determined on a PerkinElmer 241 polarimeter. Analytical HPLC was carried out on a Shimadzu LC-10AT liquid chromatography, and preparative HPLC separation was performed on a YMC-Pack ODS-A column (10 × 250 mm, 5 μm; YMC-Pack, Japan), equipped with a Shimadzu LC-8A pump and a Shimadzu SPD-10A UV–vis detector. Column chromatography was performed on silica gel G (200–300 mesh; Qingdao Haiyang Chemical Factory, Qingdao, China) and Sephadex LH-20 (Pharmacia, Piscataway, NJ, USA) columns. Thin-layer chromatography was carried out using silica gel GF254 plates, and spots were visualized by spraying with concentrated sulfuric acid–vanillin solution followed by heating.
NMR spectral methods The NMR spectra were recorded on a Bruker AVANCE-400 instrument, and the chemical shifts are given with TMS as an internal standard. The NMR experiments were carried out at 300 K with 1
the following parameters: 1H-NMR spectrum, spectrometer frequency (SF) = 400.13 MHz, spectral width (SW) = 8012.82 Hz, Fourier transform size (SI) = 65 536, acquisition time (AQ) = 4.08 s, line broadening (LB) = 0.3 Hz, relaxation delay (RD) = 1.0 s, and number of scans (NS) = 8; 13C-NMR spectrum, SF = 100.61 MHz, SW = 24 038.4 Hz, SI = 32 768, AQ = 1.36 s, LB = 1.00 Hz, RD = 2.0 s, and NS = 400 (1) or 800 (2).
Plant material The rhizomes of C. longa were purchased in Bozhou, the Anhui province of China. A voucher specimen was identified by Prof. JinCai Lu of Shenyang Pharmaceutical University and preserved in the School of Traditional Chinese Materia Medica of Shenyang Pharmaceutical University (No. 6202).
Extraction and isolation Dry rhizomes of C. longa (8 kg) were extracted by a conventional heating reflux method with 95% ethanol, and the solvent was evaporated to dryness by a vacuum rotary evaporator. Then, a crude extract (ca 590 g) was obtained. The crude extract was successively partitioned with petroleum ether, ethyl acetate, and butanol to yield three layers of extracts. Ethyl acetate layer extract (350 g) was subjected to silica gel column chromatography eluting with petroleum ether–EtOAc (100 : 0–100 : 100) to give eight fractions
13
Table 1. The H-NMR (400 MHz) and C-NMR (100 MHz) data of compounds 1–2 1 δH
No. 1′ 2′ 3′ 4′ 5′ 6′ 1 2 3
6.61 ( 1H, br s )
7.02 ( 1H, d, 7.6 ) 6.66 ( 1H, br d, 7.6 ) 1.18 ( 3H, s ) 2.55 ( 1H, d, 17.5 ) 2.47 ( 1H, d, 17.5 )
4 5
2.71 ( 1H, dd, 7.0, 16.1 ) 2.60 ( 1H, dd, 7.3, 16.1 ) 3.22 ( 1H, m ) 1.23 ( 1H, d, 6.9 ) 1.20 ( 3H, s ) 2.19 ( 3H, s )
6 7 2-CH3 4′-CH3 2-OMe 1
δC 144.9 113.5 154.3 122.1 131.1 118.5 29.3 70.1 53.6 212.6 52.7 35.1 22.1 29.2 15.5
2 HMBC
δH
C-3′, 4′, 6′, 6
6.64 ( 1H, br s )
C-1′, 3′, 4′-CH3 C-2′, 4′, 6 C-2, 3, 2-CH3
7.02 ( 1H, d, 7.6 ) 6.68 ( 1H, br d, 7.6 ) 1.17 ( 3H, s )
C-1, 2, 3, 2-CH3
2.52 (1H, d, 14.0 ) 2.46 (1H, d, 14.0 )
C-1′, 4, 6, 7
2.78 ( 1H, dd, 6.5, 16.8 ) 2.67 ( 1H, dd, 7.7, 16.8 ) 3.22 ( 1H, m ) 1.21 ( 1H, d, 6.8 ) 1.20 ( 3H, s) 2.19 ( 3H, s) 3.18 ( 3H, s)
C-1′, 2′, 6′, 4, 5, 7 C-1′, 5, 6 C-1, 2, 3 C-3′, 4′, 5′
δC
HMBC
145.7 113.6 154.1 121.7 131.1 118.7 24.9 74.5 53.2
C-1, 2, 3, 2-CH3
209.2 53.1
C-1′, 4, 6, 7
34.9 22.1 24.9 15.5 49.3
C-3′, 4′, 6
C-1′, 3′, 4′-CH3 C-2′, 4′, 6 C-2, 3, 2-CH3
C-1′, 2′, 6′, 4, 5, 7 C-1′, 5, 6 C-1, 2, 3 C-3′, 4′, 5′ C-2
13
Magn. Reson. Chem. 2015, 53, 536–538
Copyright © 2015 John Wiley & Sons, Ltd.
537
H-NMR and C-NMR recorded on ARX400 and HSQC and HMBC on AV600, in CDCl3, δ in ppm.
wileyonlinelibrary.com/journal/mrc
J. Li et al. (Fr. 1–8). Fr. 2 (12.5 g) was further separated by another silica gel column eluting with petroleum ether–EtOAc (100 : 1–100 : 100) to afford seven fractions (Fr. 2.1–2.7). Fr .2.5 was further separated by Sephadex LH-20 eluting with MeOH to obtain four fractions (Fr. 2.5.1–2.5.4). Fr. 2.5.4 was purified by preparative HPLC eluting with 52% MeOH–H2O to yield compounds 1 (29 mg, tR 30.4 min), 2 (13 mg, tR 60.1 min), and 5 (45 mg, tR 72.0 min). Fr. 2.6 was further separated by another silica gel column eluting with petroleum ether–EtOAc (100 : 1–100 : 20) to afford seven fractions (Fr. 2.6.1– 2.6.7). Fr. 2.6.2 was further separated by Sephadex LH-20 eluting with MeOH to obtain four fractions (Fr. 2.6.2.1–2.6.2.4). Fr. 2.6.2.1 was purified by preparative HPLC eluting with 50% MeOH–H2O to yield Fr. 2.6.2.1.1 and Fr. 2.6.2.1.2 (21 mg, tR 46 min). Fr. 2.6.2.1.2 was further separated by preparative thin-layer chromatograph eluting with petroleum ether–acetone (3 : 1) to yield compound 4 (10 mg, Rf = 0.24). Fr. 2.6.2.2 was purified by preparative HPLC eluting with 55% MeOH–H2O to yield compound 3 (162 mg, tR 87 min). (6S)-2-Hydroxy-6-(4-hydroxy-3-methylphenyl)-2-methylheptan4-one (1): colourless, viscous oil; [α] 20D +28.0 (ca 0.865, MeOH); UV (MeOH) λmax 203 (0.66), 214 (0.47), and 274 (0.12) nm; IR (KBr) λmax 3392, 2971, 2929, 1697, 1619, 1590, 1457, 1423, 1379, 1254, 1162, 1123, 992, 911, 811, and 639 cm 1; HRESIMS m/z 273.1453 [M + Na]+ (calcd for C15H22NaO3, 273.1467); 1H and 13 C-NMR and 2D NMR data are shown in Table 1. (6S)-6-(4-Hydroxy-3-methylphenyl)-2-methoxy-2-methylheptan4-one (2): colourless, viscous oil; [α] 20D +29.0 (ca 0.675, MeOH);
UV (MeOH) λmax 204 (0.50), 211 (0.34), and 277 (0.08); IR (KBr) λmax 3677, 3304, 2970, 2929, 1705, 1616, 1590, 1456, 1423, 1366,1254, 1186, 1121, 1074, 993, 865, 809, and 640 cm 1; HRESIMS m/z 287.1623 [M + Na]+ (calcd for C16H24NaO3, 287.1624); 1H and 13 C-NMR and 2D NMR data are shown in Table 1. Acknowledgements This paper was financially supported by Program for Innovative Research Team of the Ministry of Education and Program for Liaoning Innovative Research Team in University.
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