The genus Aphanamixis (Meliaceae) comprising about 5 species and varieties is mainly distributed in China, India and Indonesia. Aphanamixis grandifolia, an arbor tree mainly growing in southern China, is a medicinal plant employed as an astringent for spleen, liver, tumors, abdominal diseases, and applied in treatment of rheumatism in southeast Asia.
1)It has not been chemically studied previously. In our current study, four new compounds (1, 2, 6, 7) and three known compounds (3-5) were isolated from aerial parts of Aphanamixis grandifolia collected from Hainan Province, People's Republic of China. The structures of the new compounds were characterized using spectroscopic methods, and the structure of compound 1 was confirmed by single-crystal X-ray diffraction analysis. The known compounds were elucidated by comparing their spectroscopic data with those reported in the literature. Their structures were identified as (23E)-25-methylcycloart-23-en-3b-ol (1), a novel triterpenoid possessing a C 31 skeleton, (17E)-cycloart-17,26-dien3b-ol (2), (23E)-cycloart-23-en-3b,25-diol (3), 2) (23E)-25-methoxycycloart-23-en-3b-ol (4), 2) cycloart-3b,25-diol (5), 3) 4R-hydroxy-4-(9S-hydroxy-12-methylhexan-6-yl)-3-methylcyclopent-2-enone (6), and 7-hydroxy-5-(2Ј-hydroxy-4Ј,5Ј-dimethoxyphenyl)-2-methoxy-6-methyl-1,4-naphthoquinone (7). In addition, the cytotoxicities of the compounds were evaluated against selected cancer cell lines, including human leukaemia cell (HL-60), human hepatoma cell (Hep G2), and human cervical carcinoma cell (HeLa) lines. The compound 3 was active (HL60 cell, IC 50 ϭ5.97 mg/ml; Hep G2, IC 50 ϭ 20.85 mg/ml; HeLa, IC 50 ϭ24.89 mg/ml), compounds 1, 2, 5, 6 and 7 exhibited modest cytotoxicities. Herein we report the isolation, structural elucidation, and biological activities of these compounds.
Results and DiscussionThe ethanolic extract of the aerial parts of Aphanamixis grandifolia was concentrated under vacuum and then subjected repeatedly to column chromatography over silica gel, Sephadex LH-20, and MCI yield compounds 1-7 (Chart 1).The 1 H-NMR spectra of compounds 1-5 indicated the presence of a cycloartane skeleton with 3b-ol group on C-3.2)This fact was evidenced by the typical H-19 doublets at d H 0.33 (Jϭ3.9 Hz) and 0.55 (Jϭ3.9 Hz), and the oxygenated methine near at d H 3.30 (m). Comparison of the 13 C-NMR spectra of 1-5 with those of related cycloart-3b-ol compounds in the literature, 2) the methylene of C-19 at d C 30.0 and the methine of C-3 at d C 78.8, confirmed that these were all 3b-hydroxycycloartanes.Compound 1 was obtained as a colorless crystal. The high resolution-electronspray ionization-mass spectra (HR-ESI-MS) displayed a molecular ion peak at m/z 441.4100 [Mϩ H] ϩ (Calcd for C 31 H 53 O, 441.4096) consistent with a molecular formula of C 31 H 52 O, requiring seven degrees of unsaturation, which was confirmed by 13 C-NMR and distortionless enhancement by polarization transfer (DEPT) analysis. The 13 C-NMR spectrum indicated 31 resonances ascribed to seven tertiary methyl, one...