title: Cytotoxic pentacyclic triterpenoids from Combretum oliviforme.
abstract: Four pentacyclic triterpenoids were obtained from the leaves of Combretum oliviforme Chao, 3beta-hydroxyolean-12-en-28-oic acid (1), 23-O-[alpha-L-(4'-acetylrhamnopyranosyl)]-imberbic acid (2), 23-acetoxy-3beta-acetylimberbic acid-29-methyl ester (3), and 23-O-[alpha-L-rhamnopyranosyl]-1,3beta-diacetylimberbic acid (4). Hydrolysis of 2 and 4 gave 23-hydroxyimberbic acid (5). The structures were elucidated by NMR, electrospray ionization mass spectrometry (ESIMS) and comparison with literature data. Compounds 1, 2, 3 and 4 were isolated from C. oliviforme Chao leaves for the first time and 3 for the first time from any natural source. All compounds were tested in vitro for their activity against human lung cancer cell line SPC-A-1, human erythroleukaemic line K562 and human gastric cancer SGC-7901 cells. Compounds 1, 3, 4 and 5 had cytotoxic activity for the three cell lines with IC50 0.69-69.68 microM. These results suggest that the presence of acetyl group in the triterpene aglycone structure plays an essential role for cytotoxic activity.
authors.affiliation: Key Laboratory of Tropical Medicinal Plant Chemistry of Ministry of Education, College of Chemistry & Chemical Engineering, Hainan Normal University, Haikou, China 571158.
authors.forename: Xiao-Peng
authors.initials: XP
authors.lastname: Wu
authors.forename: Chang-Ri
authors.initials: CR
authors.lastname: Han
authors.forename: Guang-Ying
authors.initials: GY
authors.lastname: Chen
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yuan
authors.forename: Jian-Ying
authors.initials: JY
authors.lastname: Xie
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry* / Q000633:toxicity*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D029765:Combretum / Q000737:chemistry*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D014315:Triterpenes / Q000737:chemistry* / Q000633:toxicity*
chemical_list: D000970:Antineoplastic Agents; D014315:Triterpenes