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Pterisemipol, a novel sesquiterpenoid from Pteris semipinnata L.
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Chinese Chemical Letters 18 (2007) 1386–1388 www.elsevier.com/locate/cclet
Pterisemipol, a novel sesquiterpenoid from Pteris semipinnata L. Qiang Zhang, Li Jiang Xuan * State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, China Received 29 June 2007
Abstract A novel sesquiterpenoid, pterisemipol, was isolated from Pteris semipinnata L. Its skeleton, namely pterisane, was considered to be rearranged from protoilludane and its structure was elucidated on the basis of spectroscopic analysis. # 2007 Li Jiang Xuan. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Pteris semipinnata L.; Pterisemipol; Pterisane; Sesquiterpenoid
Pteris semipinnata L. (family Pteridaceae) is widely distributed in China and has been widely utilized as folk medicine to treat toothache, diarrhea, jaundices and viper bites [1]. Diterpenes and sesquiterpenoids were isolated in previous studies [1,2], some of which showed proliferative inhibition of several tumor cell lines, such as SPC-A-1, HL60, K562 [3,4]. Our further investigation on this fern resulted in a sesquiterpenoid with a novel tricyclic skeleton. Its structure was determined by spectroscopic analysis. Herein, we report the isolation and structural elucidation of compound 1. The herbages of P. semipinnata L. were collected in Nanning, Guangxi Province, China, in May 2005. The airdried, powdered herbages (5 kg) were extracted with 70% acetone at room temperature for three times (each of 3 days). After concentration in vacuum to remove organic solvents, the suspended residue was removed by centrifugation. The aqueous solution was submitted to Diaion HP-20 gel CC eluted with methanol/water gradiently and separated into five fractions. The 75% methanol eluting fraction (25 g) was submitted to column chromatography on MCI gel CHP-20P column, Cosmosil 25 C18-OPN column and reverse-phased C8 silica gel column, respectively to afford 1 (12 mg). Compound 1 [5], with the molecular formula C15H24O3 determined by HRESIMS ([M + Na]+ 275.1635; calcd. 275.1623), was obtained as amorphous powder. Carbon–carbon double bond (1635 cm1) and hydroxyl group (3419 cm1) were indicated in IR spectrum. Fifteen carbon signals in the 13C NMR (Table 1) spectrum were assigned by DEPT experiment into two methyls, six methylenes, three methines, two sp3 quaternary carbons and two sp2 quaternary carbons. A tri-ring sesquiterpenoid skeleton was suggested according to the above-mentioned evidences and unsaturated degree. The 1H NMR spectrum (Table 1) exhibited two AB-coupled oxygenated methylenes at d 3.48,
* Corresponding author. E-mail address: [email protected] (L.J. Xuan). 1001-8417/$ – see front matter # 2007 Li Jiang Xuan. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2007.09.028
Q. Zhang, L.J. Xuan / Chinese Chemical Letters 18 (2007) 1386–1388
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Table 1 1 H and 13C NMR data of 1 (CD3OD, d ppm) Position
dHa (J in Hz)
dCb,c
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1.95 (m) 1.68 (m)
45.5 (d) 54.8 (d), 46.6 (s)
1.84 (m), 1.91 (m) 2.71 (m), 2.83 (m)
38.6 (t) 26.9 (t) 147.0 (s) 128.6 (s) 31.1 (t) 38.2 (d) 44.1 (t) 82.5 (s) 13.5 (q) 20.0 (q) 62.0 (t) 65.3 (t)
a b c
1.58 (m), 2.19 (m) 2.14 (m) 2.26 (m), 1.24 (m) 0.88 1.16 3.91 3.48
(d, 7.0) (s) (d, 12.1), 3.96 (d, 12.1) (d, 11.4), 3.55 (d, 11.4)
Spectra recorded at 400 MHz. Spectra recorded at 100 MHz. Multiplicities inferred from DEPT and HMQC experiments.
3.55 (each d, J = 11.4 Hz) and d 3.91, 3.96 (each d, J = 12.1 Hz), respectively and two methyl signals at d 0.88 (d, J = 7.0 Hz) and 1.16 (s). Besides, four methylenes and three methines with multiple coupling were diagnosed by combination of HMQC and DEPT technique. On the basis of 1H–1H COSY analysis, partial structures were deduced as showed in Fig. 1 and the linkage of these partial moieties to comprise the planar structure of 1 was based on HMBC correlations. Correlations of H-1, H-10/C11 suggested a five-membered ring. Correlations of H-8/C-6, C-7 and H-2/C-3 revealed a paralleled six-membered ring which was attached by a four-membered ring according to the correlations of H-4/C-3. One hydroxyl methyl group was linked to olefinic carbon based on the correlations of H-14/C-6, C-7, while another was connected to C-11 because of cross peak between H-15 and C-11. Singlet methyl moiety was assigned to be the angular methyl group at C-3 as it correlated with C-3. The relative configuration was defined by NOESY analysis (Fig. 2). H-2 strongly correlated with CH3 (12), CH2OH (15) and H-9, indicative of their cis configuration. On account of cross peak between them, angular methyl group as well as H-1 was in opposite orientation. Thus, the structure of 1 was determined, named as pterisemipol (Fig. 3). It has to be noted that biosynthesis of 1 does not follow the isoprene rule. Its skeleton was discovered for the first time, named as pterisane (Fig. 3), and the closely related skeleton of 1 could be traced to protoilludene isolated from mycelium of Fomitopsis insularis in 1977 [6]. As the pathway shown in Scheme 1, pterisane skeleton was proposed to
Fig. 1. Key 1H–1H COSY and HMBC correlations of 1.
Fig. 2. Selected NOE correlations of 1.
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Q. Zhang, L.J. Xuan / Chinese Chemical Letters 18 (2007) 1386–1388
Fig. 3. Structures of 1 and pterisane.
Scheme 1. Biogenetic pathway proposed for 1.
be rearranged from protoilludene, which arises from farnesyl pyrophosphate via humulene and protoilludane cation [7,8]. Pterisene was yielded by shifting methyl group at C-11 to C-1. Acknowledgments We are grateful to the staff of the analytical group of Shanghai Institute of Organic Chemistry, Chinese Academy of Science for measuring the NMR spectra and the kind help of Prof. Yang He Ming who collected and identified the plant material. References [1] [2] [3] [4] [5] [6] [7] [8]
J.H. Li, N.C. Liang, L.E. Mo, X. Zhang, C.W. He, Acta Pharm. Sin. 33 (1998) 641. K. Aoyama, N. Tanaka, N. Suzuki, T. Murakami, Y. Saiki, C.M. Chen, Chem. Pharm. Bull. 25 (1977) 2461. J.H. Li, N.C. Liang, L.E. Mo, C.W. He, X. Zhang, Chin. Pharm. Bull. 15 (1999) 49. C.W. He, N.C. Liang, L.E. Mo, J.H. Li, X. Zhang, China J. Cancer Prev. Treat. 9 (2002) 11. Compound 1, amorphous powder, ½a20 D 7.7 (c 0.35, CH3OH). S. Nozoe, K. Hisayoshi, U. Shiro, F. Jun, Tetrahedron Lett. 16 (1977) 1381. M. Naoko, F. Jun, K. Hisayoshi, I. Shigeo, N. Shigeo, O. Shigenobu, Chem. Pharm. Bull. 35 (1987) 2678. A.A. William, T.N. Thomas, S.G. Hossein, M. Can, J. Chem. 62 (1984) 531.
Chinese Chemical Letters 18 (2007) 1386–1388 www.elsevier.com/locate/cclet
Pterisemipol, a novel sesquiterpenoid from Pteris semipinnata L. Qiang Zhang, Li Jiang Xuan * State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, China Received 29 June 2007
Abstract A novel sesquiterpenoid, pterisemipol, was isolated from Pteris semipinnata L. Its skeleton, namely pterisane, was considered to be rearranged from protoilludane and its structure was elucidated on the basis of spectroscopic analysis. # 2007 Li Jiang Xuan. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: Pteris semipinnata L.; Pterisemipol; Pterisane; Sesquiterpenoid
Pteris semipinnata L. (family Pteridaceae) is widely distributed in China and has been widely utilized as folk medicine to treat toothache, diarrhea, jaundices and viper bites [1]. Diterpenes and sesquiterpenoids were isolated in previous studies [1,2], some of which showed proliferative inhibition of several tumor cell lines, such as SPC-A-1, HL60, K562 [3,4]. Our further investigation on this fern resulted in a sesquiterpenoid with a novel tricyclic skeleton. Its structure was determined by spectroscopic analysis. Herein, we report the isolation and structural elucidation of compound 1. The herbages of P. semipinnata L. were collected in Nanning, Guangxi Province, China, in May 2005. The airdried, powdered herbages (5 kg) were extracted with 70% acetone at room temperature for three times (each of 3 days). After concentration in vacuum to remove organic solvents, the suspended residue was removed by centrifugation. The aqueous solution was submitted to Diaion HP-20 gel CC eluted with methanol/water gradiently and separated into five fractions. The 75% methanol eluting fraction (25 g) was submitted to column chromatography on MCI gel CHP-20P column, Cosmosil 25 C18-OPN column and reverse-phased C8 silica gel column, respectively to afford 1 (12 mg). Compound 1 [5], with the molecular formula C15H24O3 determined by HRESIMS ([M + Na]+ 275.1635; calcd. 275.1623), was obtained as amorphous powder. Carbon–carbon double bond (1635 cm1) and hydroxyl group (3419 cm1) were indicated in IR spectrum. Fifteen carbon signals in the 13C NMR (Table 1) spectrum were assigned by DEPT experiment into two methyls, six methylenes, three methines, two sp3 quaternary carbons and two sp2 quaternary carbons. A tri-ring sesquiterpenoid skeleton was suggested according to the above-mentioned evidences and unsaturated degree. The 1H NMR spectrum (Table 1) exhibited two AB-coupled oxygenated methylenes at d 3.48,
* Corresponding author. E-mail address: [email protected] (L.J. Xuan). 1001-8417/$ – see front matter # 2007 Li Jiang Xuan. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2007.09.028
Q. Zhang, L.J. Xuan / Chinese Chemical Letters 18 (2007) 1386–1388
1387
Table 1 1 H and 13C NMR data of 1 (CD3OD, d ppm) Position
dHa (J in Hz)
dCb,c
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1.95 (m) 1.68 (m)
45.5 (d) 54.8 (d), 46.6 (s)
1.84 (m), 1.91 (m) 2.71 (m), 2.83 (m)
38.6 (t) 26.9 (t) 147.0 (s) 128.6 (s) 31.1 (t) 38.2 (d) 44.1 (t) 82.5 (s) 13.5 (q) 20.0 (q) 62.0 (t) 65.3 (t)
a b c
1.58 (m), 2.19 (m) 2.14 (m) 2.26 (m), 1.24 (m) 0.88 1.16 3.91 3.48
(d, 7.0) (s) (d, 12.1), 3.96 (d, 12.1) (d, 11.4), 3.55 (d, 11.4)
Spectra recorded at 400 MHz. Spectra recorded at 100 MHz. Multiplicities inferred from DEPT and HMQC experiments.
3.55 (each d, J = 11.4 Hz) and d 3.91, 3.96 (each d, J = 12.1 Hz), respectively and two methyl signals at d 0.88 (d, J = 7.0 Hz) and 1.16 (s). Besides, four methylenes and three methines with multiple coupling were diagnosed by combination of HMQC and DEPT technique. On the basis of 1H–1H COSY analysis, partial structures were deduced as showed in Fig. 1 and the linkage of these partial moieties to comprise the planar structure of 1 was based on HMBC correlations. Correlations of H-1, H-10/C11 suggested a five-membered ring. Correlations of H-8/C-6, C-7 and H-2/C-3 revealed a paralleled six-membered ring which was attached by a four-membered ring according to the correlations of H-4/C-3. One hydroxyl methyl group was linked to olefinic carbon based on the correlations of H-14/C-6, C-7, while another was connected to C-11 because of cross peak between H-15 and C-11. Singlet methyl moiety was assigned to be the angular methyl group at C-3 as it correlated with C-3. The relative configuration was defined by NOESY analysis (Fig. 2). H-2 strongly correlated with CH3 (12), CH2OH (15) and H-9, indicative of their cis configuration. On account of cross peak between them, angular methyl group as well as H-1 was in opposite orientation. Thus, the structure of 1 was determined, named as pterisemipol (Fig. 3). It has to be noted that biosynthesis of 1 does not follow the isoprene rule. Its skeleton was discovered for the first time, named as pterisane (Fig. 3), and the closely related skeleton of 1 could be traced to protoilludene isolated from mycelium of Fomitopsis insularis in 1977 [6]. As the pathway shown in Scheme 1, pterisane skeleton was proposed to
Fig. 1. Key 1H–1H COSY and HMBC correlations of 1.
Fig. 2. Selected NOE correlations of 1.
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Q. Zhang, L.J. Xuan / Chinese Chemical Letters 18 (2007) 1386–1388
Fig. 3. Structures of 1 and pterisane.
Scheme 1. Biogenetic pathway proposed for 1.
be rearranged from protoilludene, which arises from farnesyl pyrophosphate via humulene and protoilludane cation [7,8]. Pterisene was yielded by shifting methyl group at C-11 to C-1. Acknowledgments We are grateful to the staff of the analytical group of Shanghai Institute of Organic Chemistry, Chinese Academy of Science for measuring the NMR spectra and the kind help of Prof. Yang He Ming who collected and identified the plant material. References [1] [2] [3] [4] [5] [6] [7] [8]
J.H. Li, N.C. Liang, L.E. Mo, X. Zhang, C.W. He, Acta Pharm. Sin. 33 (1998) 641. K. Aoyama, N. Tanaka, N. Suzuki, T. Murakami, Y. Saiki, C.M. Chen, Chem. Pharm. Bull. 25 (1977) 2461. J.H. Li, N.C. Liang, L.E. Mo, C.W. He, X. Zhang, Chin. Pharm. Bull. 15 (1999) 49. C.W. He, N.C. Liang, L.E. Mo, J.H. Li, X. Zhang, China J. Cancer Prev. Treat. 9 (2002) 11. Compound 1, amorphous powder, ½a20 D 7.7 (c 0.35, CH3OH). S. Nozoe, K. Hisayoshi, U. Shiro, F. Jun, Tetrahedron Lett. 16 (1977) 1381. M. Naoko, F. Jun, K. Hisayoshi, I. Shigeo, N. Shigeo, O. Shigenobu, Chem. Pharm. Bull. 35 (1987) 2678. A.A. William, T.N. Thomas, S.G. Hossein, M. Can, J. Chem. 62 (1984) 531.