Chemical Constituents from Celastrus monospermus

Abstract

The genus Celastrus belongs to the family Celastraceae, comprising 50 species, of which 30 species are distributed in China [1]. Celastrus monospermus Roxb is a liana plant belonging to the Celastraceae family and is widely distributed in Guizhou, Guangdong, Hainan, Guangxi, and Yunnan Provinces of China. It grows at 300–1500 m above sea level [2]. Previous chemical studies led to the isolation of triterpenens with the friedelane skeleton, which exhibited diverse activities in rheumatism, leukemia, and skin diseases [3–5]. In the course of our research on the chemical constituents of C. monospermus Roxb., 14 compounds were isolated and identified by comparison of their ESI-MS and NMR spectroscopic data with those reported in the literature. Among them, compounds 2–12 were isolated from this plant for the first time. The stems of C. monospermus Roxb were collected from Xishuangbanna, Yunnan Province of China in July 2010 and identified by Prof. Zhang Hangmin (Second Military Medical University). A voucher specimen (No. 201007DZT) has been deposited at the School of Pharmacy, Shanghai Jiao Tong University. The air-dried and powdered plant material (5.0 kg) was extracted three times with 95% EtOH at room temperature. After evaporation of the EtOH under reduced pressure, the viscous residue (296 g) was suspended in H2O and then partitioned successively with petroleum ether and EtOAc, yielding 32.0 g and 78.1 g, respectively. The petroleum ether extract was applied to a silica gel column eluting with petroleum ether–EtOAc gradient (100:1 to 0:100) to obtain five fractions (Fr. 1–Fr. 5). Fraction 2 (2.1 g) was subjected to repeated column chromatography over silica gel eluted with petroleum ether–EtOAc (80:20) to provide compounds 1 (1.2 g) and 9 (10.3 mg). Fraction 3 (2.4 g) was isolated on Sephadex LH-20 (CH2Cl2–MeOH 1:1) to afford compounds 2 (14.0 mg) and 13 (85.9 mg). Compounds 3 (4.4 mg) and 4 (10.0 mg) were purified by crystallization in acetone from Fr. 4 (3.1 g). Fraction 5 (2.1 g) was rechromatographed on silica gel eluted with petroleum ether–EtOAc gradient (10:1 to 0:1) to obtain fractions A–D; Fr. C (0.7 g) was submitted to preparative HPLC [eluted by MeOH–H2O (70:30)] to obtain compounds 10 (13.0 mg) and 11 (7.7 mg). The EtOAc extract was chromatographed on a silica gel column eluting with CH2Cl2–MeOH (50:1 to 5:1) to obtain five fractions (A1–A5). Compounds 8 (33.4 mg) and 14 (57.4 mg) were crystalized from A2 (6.2 g) in acetone. Fraction A3 (5.1 g) was separated by silica gel column again, and the third sub-fraction was subjected to preparative HPLC [eluted by MeOH–H2O (70:30)] to give compounds 7 (5.8 mg) and 12 (5.8 mg). Compounds 5 (14.5 mg) and 6 (4.0 mg) were obtained after purification of A5 (1.3 g) by Sephadex LH-20 (MeOH) and preparative HPLC [eluted by MeOH–H2O (40:60)]. Friedelan-3-one (1). C30H50O. Colorless crystals, mp 229–321 C. ESI-MS (positive) m/z 449 [M + Na] +. Compound 1 was characterized as friedelan-3-one by comparison of the physical and spectral data with the literature [6]. Woodwardic Acid (2). C30H43O3. Colorless crystals, mp 264–265 C. ESI-MS (negative) m/z 455 [M – H]–. Compound 2 was characterized as woodwardic acid by comparison of the physical and spectral data with the literature [7]. Stigmastane-3,6-dione (3). C29H48O2. Colorless crystals, mp 178–180 C. ESI-MS (negative) m/z 427 [M – H] –. Compound 3 was characterized as stigmastane-3,6-dione by comparison of the physical and spectral data with the literature [8]. Stigmast-4-en-6 -ol-3-one (4). C29H48O2. Colorless crystals, mp 189–191 C. ESI-MS (negative) m/z 427 [M – H]–. Compound 4 was characterized as stigmast-4-en-6 -ol-3-one by comparison of the MS and NMR spectral data with the literature [9]. ( )-Catechin (5). C15H14O6. Orange powder, mp 214–216 C. ESI-MS (positive) m/z 313 [M + Na] Compound 5 was characterized as (+)-catechin by comparison of the MS and NMR spectral data with the literature [10].