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A new phenylethanoid glycoside from Rabdosia lophanthoides (Buch.-Ham.ex D.Don) Hara.
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Chinese Chemical Letters 20 (2009) 453–455 www.elsevier.com/locate/cclet
A new phenylethanoid glycoside from Rabdosia lophanthoides (Buch.-Ham.ex D.Don) Hara. Wei Sheng Feng *, Xin Yu Zang, Xiao Ke Zheng, Yan Zhi Wang Henan College of Traditional Chinese Medicine, Zhengzhou 450008, China Received 29 August 2008
Abstract A new phenylethanoid glycoside, 3-hydroxy-4-methoxy-b-phenylethoxy-O-a-L-rhamnopyranosyl-(1 ! 3)-2-O-acetyl-O-b-Dglucopyranoside, named lophanthoside A, was isolated from Rabdosia lophanthoides (Buch.-Ham.ex D.Don) Hara. Its structure was determined by spectroscopic evidences. # 2008 Wei Sheng Feng. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Rabdosia lophanthoides; Lophanthoside A; Phenylethanoid glycoside
Isodon (Rabdosia) is a cosmopolitan and important genus of the Labiatae (Lamiaceae) family. About 150 species of undershrubs, sub-undershrubs or perennial herbs are found throughout the world mainly in tropical and subtropical Asia [1]. Rabdosia lophanthoides (Buch.-Ham.ex D.Don) Hara. is a special species of Isodon for the treatment of acute icteric hepatitis, acute cholecystitis, sphagitis, gynaecopathia [2], and so on. However, few of the phytochemical studies of the plant have been reported previously. In this paper, a new phenylethanoid glycoside, 3-hydroxy-4methoxy-b-phenylethoxy-O-a-L-rhamnopyranosyl-(1 ! 3)-2-O-acetyl-O-b-D-glucopyranoside (lophanthoside A, 1) was isolated from the extract of the whole plant of R. lophanthoides and its structure was determined by spectroscopic methods. Compound 1 was isolated from the 50% aqueous acetone extract of the whole plant of R. lophanthoides, and further purified by repeated column chromatography on silica gel and Toyopearl HW-40. It was a colourless, amorphous powder. m.p. 223–225 8C, [a]20D 22.6 (c 0.32, MeOH), and UV (MeOH) lmax (log e) 280 nm. Its HR-ESI-MS showed [M+Na]+ at m/z 541.1880 (calcd. for C23H34O13Na 541.1897). Meanwhile, the IR spectrum exhibited the presence of hydroxyl (3415 cm1), carbonyl (1739 cm1), and aromatic rings (1591, 1513 cm1). The 1H NMR spectrum of 1 exhibited signals accounting for one 3,4-dihydroxyphenylethanol moiety at d 6.60 (1H, br.d, J = 8.2 Hz, H-6), 6.79 (1H, br.d, J = 8.2 Hz, H-5), 6.69 (1H, br.s, H-2), 3.69, 3.63 (each 1H, m, H2-a), 2.67 (2H, t, J = 6.2 Hz, H2b). Two anomeric protons d 4.49 (1H, d, J = 8.2 Hz, H-10 of b-D-glucose) and d 4.79 (1H, br.s, H-100 of a-L-rhamnose) indicated the presence of two sugars in 1. Additionally, one methoxyl signal at d 3.75 (3H, s) and one methyl signal at d 1.98 (3H, s) were observed. The 13C NMR spectroscopic data showed signals of one 3,4-dihydroxyphenylethanol moiety at d 132.3 (C-1), 116.4 (C-2), 146.3 (C-3), 146.5 (C-4), 112.3 (C-5), 120.4 (C-6), 70.5 (C-a), and 35.3 (C-b),
* Corresponding author. E-mail address: [email protected] (W.S. Feng). 1001-8417/$ – see front matter # 2008 Wei Sheng Feng. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2008.12.015
454 Table 1 1 H NMR (400 MHz) and No.
W.S. Feng et al. / Chinese Chemical Letters 20 (2009) 453–455 13
C NMR (100 MHz) data of lophanthoside A (CD3COCD3, d ppm). dC
dH
1 2 3 4 5 6 a b OCH3
6.79 6.60 3.69 2.67 3.75
(br.d, 1H, J = 8.2 Hz) (br.d, 1H, J = 8.2 Hz) (m, 1H), 3.63 (m, 1H) (t, 2H, J = 6.2 Hz) (s, 3H)
132.3 116.4 146.3 146.5 112.3 120.4 70.5 35.3 56.0
Glucose 10 20 30 40 50 60
4.49 4.73 3.69 3.68 3.41 4.83
(d, 1H, J = 8.2 Hz) (m, 1H) (m, 1H) (m, 1H) (m, 1H) (m, 1H), 4.66 (m, 1H)
100.5 74.0 81.4 71.1 77.0 61.5
4.79 3.63 3.52 3.25 3.50 1.17
(br.s, 1H) (m, 1H) (m, 1H) (m, 1H) (m, 1H) (d, 3H, J = 6.2 Hz)
101.7 72.6 71.3 72.7 69.3 17.4 170.9 20.6
Rhamnose 100 200 300 400 500 600 COCH3 COCH3
6.69 (br.s, 1H)
1.98 (s, 3H)
one glucose moiety at d 100.5 (C-10 ), 74.0 (C-20 ), 81.4 (C-30 ), 71.1 (C-40 ), 77.0 (C-50 ), 61.5 (C-60 ), one rhamnose moiety at d 101.7 (C-100 ), 72.6 (C-200 ), 71.3 (C-300 ), 72.7 (C-400 ), 69.3 (C-500 ), 17.4 (C-600 ), one acetyl group at d 170.9, 20.6 and one methoxyl signal at d 56.0. The 1H NMR and 13C NMR signals were assigned by means of HSQC, HMBC and NOESY. In the HSQC spectrum, the signal at d 1.98 (3H, s) was found to be coupled with d 20.6, indicating the structure of acetyl group. In the HMBC spectrum, the following correlative signals were observed: d 4.79 (H-100 ) correlated with the carbon signals at d 81.4 (C-30 ), 71.3 (C-300 ), 69.3 (C-500 ), which revealed that C-100 of rhamnose was linked to C-30 of the glucose moiety. The signal at d 4.73 (H-20 ) correlated with the carbon signals at d 81.4 (C-30 ), 100.5 (C-10 ), 170 (C O), indicating that the acetyl group was linked to C-20 of the glucose moiety. The signal at d 4.49 (H-10 ) correlated with the carbon signal at d 70.5 (C-a), which revealed that C-10 of the glucose moiety was linked to C-a of the phenylethanol group. d 6.60 (H-6), 6.79 (H-5), 6.69 (H-2) and 3.75 (OCH3) all correlated with the carbon signal at d 146.5(C-4), indicating that the methoxyl was linked to C-4. This was confirmed by NOE correlations between the methoxyl group and H-5. According to the literature [3], the structure of 1 is closely related to that of cistansinenside A, without the signals of
Fig. 1. The chemical structure, key HMBC and NOE correlations for lophanthoside A.
W.S. Feng et al. / Chinese Chemical Letters 20 (2009) 453–455
455
caffeoyl group. Therefore, the structure of 1 was established as 3-hydroxy-4-methoxy-b-phenylethoxy-O-a-Lrhamnopyranosyl-(1 ! 3)-2-O-acetyl-O-b-D-glucopyranoside, which was named lophanthoside A (Table 1 and Fig. 1). Acknowledgments This work was supported by the Key Science-Technology Project of the National ‘11th Five-Year Plan’ of China (No. 2006BAI06A15-3). The authors are grateful to Prof. Cheng Ming Dong for collecting and identifying the plant material, and thank Prof. Jian Xun Kang for recording the NMR spectra. References [1] H.D. Sun, S.X. Huang, Q.B. Han, Nat. Prod. Rep. 23 (2006) 673. [2] Edit Committee of Flora of China, Flora of China, vol. 66 [M], Science Press, Beijing, 1977, pp. 479–480. [3] P.F. Tu, H.M. Shi, Z.H. Song, et al. J. Asian Nat. Prod. Res. 9 (2007) 81.
Chinese Chemical Letters 20 (2009) 453–455 www.elsevier.com/locate/cclet
A new phenylethanoid glycoside from Rabdosia lophanthoides (Buch.-Ham.ex D.Don) Hara. Wei Sheng Feng *, Xin Yu Zang, Xiao Ke Zheng, Yan Zhi Wang Henan College of Traditional Chinese Medicine, Zhengzhou 450008, China Received 29 August 2008
Abstract A new phenylethanoid glycoside, 3-hydroxy-4-methoxy-b-phenylethoxy-O-a-L-rhamnopyranosyl-(1 ! 3)-2-O-acetyl-O-b-Dglucopyranoside, named lophanthoside A, was isolated from Rabdosia lophanthoides (Buch.-Ham.ex D.Don) Hara. Its structure was determined by spectroscopic evidences. # 2008 Wei Sheng Feng. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Rabdosia lophanthoides; Lophanthoside A; Phenylethanoid glycoside
Isodon (Rabdosia) is a cosmopolitan and important genus of the Labiatae (Lamiaceae) family. About 150 species of undershrubs, sub-undershrubs or perennial herbs are found throughout the world mainly in tropical and subtropical Asia [1]. Rabdosia lophanthoides (Buch.-Ham.ex D.Don) Hara. is a special species of Isodon for the treatment of acute icteric hepatitis, acute cholecystitis, sphagitis, gynaecopathia [2], and so on. However, few of the phytochemical studies of the plant have been reported previously. In this paper, a new phenylethanoid glycoside, 3-hydroxy-4methoxy-b-phenylethoxy-O-a-L-rhamnopyranosyl-(1 ! 3)-2-O-acetyl-O-b-D-glucopyranoside (lophanthoside A, 1) was isolated from the extract of the whole plant of R. lophanthoides and its structure was determined by spectroscopic methods. Compound 1 was isolated from the 50% aqueous acetone extract of the whole plant of R. lophanthoides, and further purified by repeated column chromatography on silica gel and Toyopearl HW-40. It was a colourless, amorphous powder. m.p. 223–225 8C, [a]20D 22.6 (c 0.32, MeOH), and UV (MeOH) lmax (log e) 280 nm. Its HR-ESI-MS showed [M+Na]+ at m/z 541.1880 (calcd. for C23H34O13Na 541.1897). Meanwhile, the IR spectrum exhibited the presence of hydroxyl (3415 cm1), carbonyl (1739 cm1), and aromatic rings (1591, 1513 cm1). The 1H NMR spectrum of 1 exhibited signals accounting for one 3,4-dihydroxyphenylethanol moiety at d 6.60 (1H, br.d, J = 8.2 Hz, H-6), 6.79 (1H, br.d, J = 8.2 Hz, H-5), 6.69 (1H, br.s, H-2), 3.69, 3.63 (each 1H, m, H2-a), 2.67 (2H, t, J = 6.2 Hz, H2b). Two anomeric protons d 4.49 (1H, d, J = 8.2 Hz, H-10 of b-D-glucose) and d 4.79 (1H, br.s, H-100 of a-L-rhamnose) indicated the presence of two sugars in 1. Additionally, one methoxyl signal at d 3.75 (3H, s) and one methyl signal at d 1.98 (3H, s) were observed. The 13C NMR spectroscopic data showed signals of one 3,4-dihydroxyphenylethanol moiety at d 132.3 (C-1), 116.4 (C-2), 146.3 (C-3), 146.5 (C-4), 112.3 (C-5), 120.4 (C-6), 70.5 (C-a), and 35.3 (C-b),
* Corresponding author. E-mail address: [email protected] (W.S. Feng). 1001-8417/$ – see front matter # 2008 Wei Sheng Feng. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2008.12.015
454 Table 1 1 H NMR (400 MHz) and No.
W.S. Feng et al. / Chinese Chemical Letters 20 (2009) 453–455 13
C NMR (100 MHz) data of lophanthoside A (CD3COCD3, d ppm). dC
dH
1 2 3 4 5 6 a b OCH3
6.79 6.60 3.69 2.67 3.75
(br.d, 1H, J = 8.2 Hz) (br.d, 1H, J = 8.2 Hz) (m, 1H), 3.63 (m, 1H) (t, 2H, J = 6.2 Hz) (s, 3H)
132.3 116.4 146.3 146.5 112.3 120.4 70.5 35.3 56.0
Glucose 10 20 30 40 50 60
4.49 4.73 3.69 3.68 3.41 4.83
(d, 1H, J = 8.2 Hz) (m, 1H) (m, 1H) (m, 1H) (m, 1H) (m, 1H), 4.66 (m, 1H)
100.5 74.0 81.4 71.1 77.0 61.5
4.79 3.63 3.52 3.25 3.50 1.17
(br.s, 1H) (m, 1H) (m, 1H) (m, 1H) (m, 1H) (d, 3H, J = 6.2 Hz)
101.7 72.6 71.3 72.7 69.3 17.4 170.9 20.6
Rhamnose 100 200 300 400 500 600 COCH3 COCH3
6.69 (br.s, 1H)
1.98 (s, 3H)
one glucose moiety at d 100.5 (C-10 ), 74.0 (C-20 ), 81.4 (C-30 ), 71.1 (C-40 ), 77.0 (C-50 ), 61.5 (C-60 ), one rhamnose moiety at d 101.7 (C-100 ), 72.6 (C-200 ), 71.3 (C-300 ), 72.7 (C-400 ), 69.3 (C-500 ), 17.4 (C-600 ), one acetyl group at d 170.9, 20.6 and one methoxyl signal at d 56.0. The 1H NMR and 13C NMR signals were assigned by means of HSQC, HMBC and NOESY. In the HSQC spectrum, the signal at d 1.98 (3H, s) was found to be coupled with d 20.6, indicating the structure of acetyl group. In the HMBC spectrum, the following correlative signals were observed: d 4.79 (H-100 ) correlated with the carbon signals at d 81.4 (C-30 ), 71.3 (C-300 ), 69.3 (C-500 ), which revealed that C-100 of rhamnose was linked to C-30 of the glucose moiety. The signal at d 4.73 (H-20 ) correlated with the carbon signals at d 81.4 (C-30 ), 100.5 (C-10 ), 170 (C O), indicating that the acetyl group was linked to C-20 of the glucose moiety. The signal at d 4.49 (H-10 ) correlated with the carbon signal at d 70.5 (C-a), which revealed that C-10 of the glucose moiety was linked to C-a of the phenylethanol group. d 6.60 (H-6), 6.79 (H-5), 6.69 (H-2) and 3.75 (OCH3) all correlated with the carbon signal at d 146.5(C-4), indicating that the methoxyl was linked to C-4. This was confirmed by NOE correlations between the methoxyl group and H-5. According to the literature [3], the structure of 1 is closely related to that of cistansinenside A, without the signals of
Fig. 1. The chemical structure, key HMBC and NOE correlations for lophanthoside A.
W.S. Feng et al. / Chinese Chemical Letters 20 (2009) 453–455
455
caffeoyl group. Therefore, the structure of 1 was established as 3-hydroxy-4-methoxy-b-phenylethoxy-O-a-Lrhamnopyranosyl-(1 ! 3)-2-O-acetyl-O-b-D-glucopyranoside, which was named lophanthoside A (Table 1 and Fig. 1). Acknowledgments This work was supported by the Key Science-Technology Project of the National ‘11th Five-Year Plan’ of China (No. 2006BAI06A15-3). The authors are grateful to Prof. Cheng Ming Dong for collecting and identifying the plant material, and thank Prof. Jian Xun Kang for recording the NMR spectra. References [1] H.D. Sun, S.X. Huang, Q.B. Han, Nat. Prod. Rep. 23 (2006) 673. [2] Edit Committee of Flora of China, Flora of China, vol. 66 [M], Science Press, Beijing, 1977, pp. 479–480. [3] P.F. Tu, H.M. Shi, Z.H. Song, et al. J. Asian Nat. Prod. Res. 9 (2007) 81.