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A new hopane triterpenoid from Saxiglossum angustissimum
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Chinese Chemical Letters 19 (2008) 835–836 www.elsevier.com/locate/cclet
A new hopane triterpenoid from Saxiglossum angustissimum Hui Fang Pi, Zhi Hong Zhong, Han Li Ruan *, Peng Zhang, Yong Hui Zhang, Ji Zhou Wu Faculty of Pharmaceutical Sciences, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430030, PR China Received 9 January 2008
Abstract A new hopane triterpenoid, hopane 22, 29-diol-29-formate (1), has been isolated from the whole herbs of Saxiglossum angustissimum (Gies.) Ching and its structure has been successfully determined on the basis of spectroscopic evidences. # 2008 Han Li Ruan. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Saxiglossum angustissimum; Hopane; Hopane-22; 29-Diol-29-formate
Saxiglossum angustissimum (Gies.) Ching is a perennial herb of Polypodiaceae. With a main distribution in middle China, it is found to be growing on the brae of about 800–1600 m altitude mountains. As a folk medicinal plant, it is proved to be effective in clearing away heat and toxic materials, dispelling blood stasis and promoting subsidence of swelling. However, the chemical constituents of the plant and also the genus Saxiglossum have never been studied before. In the present study, a new hopane triterpenoid has been isolated from the whole herbs of the plant by silica gel column chromatography, Sephadex LH-20 column chromatography and HPLC. Its structure has been identified to be hopane 22, 29-diol-29-formate (1) by spectroscopic data analysis (IR, 1H NMR, 13C NMR, 2D NMR, FAB-MS and TOF-MS). Compound 1 was obtained as white powders (petroleum-EtOAc), m.p. 117–119 8C. Liebermann–Burchard reaction was positive, with a molecular formula of C31H52O3 based on 13C NMR and positive HR-TOFMS data at 472.3932 [M]+. The IR spectrum of 1 showed the presence of hydroxyl group(s) (3524 cm 1) and formyl group (2850 and 1719 cm 1). The 1H NMR (in CDCl3, 500 MHz) signal at d 8.09 (s, 1H, H-31) and 13C NMR signal at d 161.1 (C31) suggested compound 1 has a formoxyl group in the structure. The 1H NMR spectrum of 1 also indicated the presence of 7 tertiary methyl groups at d 1.15 (s, 3H, H-30), 0.95 (s, 6H, H-26, 27), 0.84 (s, 3H, H-23), 0.80 (s, 3H, H25), 0.78 (s, 3H, H-24), 0.75 (s, 3H, H-28) and an oxygenated CH2 group at d 4.01, 4.05 (each d, 1H, J = 11.1 Hz, H29). In addition, the presence of the oxygen-bearing CH2 group was confirmed by the HSQC cross peaks between proton signals at d 4.01, 4.05 and the carbon signal at d 71.4 (C-29). The 13C NMR (in CDCl3, 125 MHz) spectrum of 1 showed 31 carbon signals. They are 5 quaternary carbons including an oxygenated carbon at d 74.6, 7 tertiary carbons including a formoxyl carbon at d 161.1, 12 secondary carbons including an oxygenated carbon at d 71.4 and 7 primary
* Corresponding author. E-mail address: [email protected] (H.L. Ruan). 1001-8417/$ – see front matter # 2008 Han Li Ruan. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2008.04.034
836
H.F. Pi et al. / Chinese Chemical Letters 19 (2008) 835–836
Table 1 The 13C NMR spectral data of compound 1 (125 MHz, CDCl3, d (ppm)) No.
dC
No.
dC
No.
dC
1 2 3 4 5 6 7 8 9 10 11
40.3 18.7 41.9 33.6 56.1 18.7 33.4 42.0 50.3 37.5 20.9
12 13 14 15 16 17 18 19 20 21 22
24.1 49.8 41.6 34.4 21.8 53.7 44.7 41.2 25.9 46.3 74.6
23 24 25 26 27 28 29 30 31 – –
33.2 21.6 15.8 17.0 16.7 16.0 71.4 22.9 161.1 – –
Fig. 1. The structure of compound 1.
carbons according to the DEPT experiment (see Table 1). The close similarity of the 13C NMR chemical shifts of 1 with those of reported hopane [1,2], except for those of the side chain carbons, indicated that 1 also possesses a hopane (21bH) skeleton with a –C(OH)(CH3)–CH2OCHO side chain. This conclusion was supported by the HMBC and NOESY spectra of 1: in the HMBC spectrum of 1, the H2-29 showed correlations with the carbon at d 161.1 (C-31), 74.6 (C-22) and 46.3 (C-21); in the NOESY spectrum of 1, correlated peaks between H-29 and H-16 (d 1.59 and 1.92), H-17 (d 1.47), H-21 (d 2.35) and H-30 (d 1.15) were observed. That the formoxyl group is attached to C-29 was clearly revealed by the correlations between the formoxyl proton (d 8.09, 1H, s, H-31) and C-29 (d 71.4), and between H2-29 and C-31 (d 161.1) in the HMBC spectrum. The chemical shift of the terminal methyl of H-30 at d 1.15 also supported the above point: according to the literature [3], if the formoxyl group is attached to C-30, then the chemical shift of H-29 should be at around d 1.23. So the formoxyl group is attached to C-29 rather than C-30. In the NOESY spectrum of 1, the correlation peak between H-17 (m, 1H, d 1.47) and H-21 (m, 1H, d 2.35) indicated a b-orientation of H-21, suggesting that the configuration of C-21 be S1. From the evidences above, the structure of 1 was established as hopane 22, 29-diol-29-formate (Fig. 1). Acknowledgment This research was supported by the Natural Science Foundation of Hubei (No. 2006ABA125). References [1] H. Ageta, K. Shiojima, H. Suzuki, S. Nakamura, Chem. Pharm. Bull. 41 (11) (1993) 1939. [2] K. Shiojima, Y. Arai, H. Ageta, Phytochemistry 29 (4) (1990) 1079. [3] K. Masuda, H. Yamashita, H. Shiojima, T. Itoh, H. Ageta, Chem. Pharm. Bull. 45 (4) (1997) 590.
Chinese Chemical Letters 19 (2008) 835–836 www.elsevier.com/locate/cclet
A new hopane triterpenoid from Saxiglossum angustissimum Hui Fang Pi, Zhi Hong Zhong, Han Li Ruan *, Peng Zhang, Yong Hui Zhang, Ji Zhou Wu Faculty of Pharmaceutical Sciences, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430030, PR China Received 9 January 2008
Abstract A new hopane triterpenoid, hopane 22, 29-diol-29-formate (1), has been isolated from the whole herbs of Saxiglossum angustissimum (Gies.) Ching and its structure has been successfully determined on the basis of spectroscopic evidences. # 2008 Han Li Ruan. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Saxiglossum angustissimum; Hopane; Hopane-22; 29-Diol-29-formate
Saxiglossum angustissimum (Gies.) Ching is a perennial herb of Polypodiaceae. With a main distribution in middle China, it is found to be growing on the brae of about 800–1600 m altitude mountains. As a folk medicinal plant, it is proved to be effective in clearing away heat and toxic materials, dispelling blood stasis and promoting subsidence of swelling. However, the chemical constituents of the plant and also the genus Saxiglossum have never been studied before. In the present study, a new hopane triterpenoid has been isolated from the whole herbs of the plant by silica gel column chromatography, Sephadex LH-20 column chromatography and HPLC. Its structure has been identified to be hopane 22, 29-diol-29-formate (1) by spectroscopic data analysis (IR, 1H NMR, 13C NMR, 2D NMR, FAB-MS and TOF-MS). Compound 1 was obtained as white powders (petroleum-EtOAc), m.p. 117–119 8C. Liebermann–Burchard reaction was positive, with a molecular formula of C31H52O3 based on 13C NMR and positive HR-TOFMS data at 472.3932 [M]+. The IR spectrum of 1 showed the presence of hydroxyl group(s) (3524 cm 1) and formyl group (2850 and 1719 cm 1). The 1H NMR (in CDCl3, 500 MHz) signal at d 8.09 (s, 1H, H-31) and 13C NMR signal at d 161.1 (C31) suggested compound 1 has a formoxyl group in the structure. The 1H NMR spectrum of 1 also indicated the presence of 7 tertiary methyl groups at d 1.15 (s, 3H, H-30), 0.95 (s, 6H, H-26, 27), 0.84 (s, 3H, H-23), 0.80 (s, 3H, H25), 0.78 (s, 3H, H-24), 0.75 (s, 3H, H-28) and an oxygenated CH2 group at d 4.01, 4.05 (each d, 1H, J = 11.1 Hz, H29). In addition, the presence of the oxygen-bearing CH2 group was confirmed by the HSQC cross peaks between proton signals at d 4.01, 4.05 and the carbon signal at d 71.4 (C-29). The 13C NMR (in CDCl3, 125 MHz) spectrum of 1 showed 31 carbon signals. They are 5 quaternary carbons including an oxygenated carbon at d 74.6, 7 tertiary carbons including a formoxyl carbon at d 161.1, 12 secondary carbons including an oxygenated carbon at d 71.4 and 7 primary
* Corresponding author. E-mail address: [email protected] (H.L. Ruan). 1001-8417/$ – see front matter # 2008 Han Li Ruan. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2008.04.034
836
H.F. Pi et al. / Chinese Chemical Letters 19 (2008) 835–836
Table 1 The 13C NMR spectral data of compound 1 (125 MHz, CDCl3, d (ppm)) No.
dC
No.
dC
No.
dC
1 2 3 4 5 6 7 8 9 10 11
40.3 18.7 41.9 33.6 56.1 18.7 33.4 42.0 50.3 37.5 20.9
12 13 14 15 16 17 18 19 20 21 22
24.1 49.8 41.6 34.4 21.8 53.7 44.7 41.2 25.9 46.3 74.6
23 24 25 26 27 28 29 30 31 – –
33.2 21.6 15.8 17.0 16.7 16.0 71.4 22.9 161.1 – –
Fig. 1. The structure of compound 1.
carbons according to the DEPT experiment (see Table 1). The close similarity of the 13C NMR chemical shifts of 1 with those of reported hopane [1,2], except for those of the side chain carbons, indicated that 1 also possesses a hopane (21bH) skeleton with a –C(OH)(CH3)–CH2OCHO side chain. This conclusion was supported by the HMBC and NOESY spectra of 1: in the HMBC spectrum of 1, the H2-29 showed correlations with the carbon at d 161.1 (C-31), 74.6 (C-22) and 46.3 (C-21); in the NOESY spectrum of 1, correlated peaks between H-29 and H-16 (d 1.59 and 1.92), H-17 (d 1.47), H-21 (d 2.35) and H-30 (d 1.15) were observed. That the formoxyl group is attached to C-29 was clearly revealed by the correlations between the formoxyl proton (d 8.09, 1H, s, H-31) and C-29 (d 71.4), and between H2-29 and C-31 (d 161.1) in the HMBC spectrum. The chemical shift of the terminal methyl of H-30 at d 1.15 also supported the above point: according to the literature [3], if the formoxyl group is attached to C-30, then the chemical shift of H-29 should be at around d 1.23. So the formoxyl group is attached to C-29 rather than C-30. In the NOESY spectrum of 1, the correlation peak between H-17 (m, 1H, d 1.47) and H-21 (m, 1H, d 2.35) indicated a b-orientation of H-21, suggesting that the configuration of C-21 be S1. From the evidences above, the structure of 1 was established as hopane 22, 29-diol-29-formate (Fig. 1). Acknowledgment This research was supported by the Natural Science Foundation of Hubei (No. 2006ABA125). References [1] H. Ageta, K. Shiojima, H. Suzuki, S. Nakamura, Chem. Pharm. Bull. 41 (11) (1993) 1939. [2] K. Shiojima, Y. Arai, H. Ageta, Phytochemistry 29 (4) (1990) 1079. [3] K. Masuda, H. Yamashita, H. Shiojima, T. Itoh, H. Ageta, Chem. Pharm. Bull. 45 (4) (1997) 590.