Isolation and identification of ent-kaurane-type diterpenoids from Rabdosia serra (MAXIM.) HARA leaf and their inhibitory activities against HepG-2, MCF-7, and HL-60 cell lines

A phytochemical investigation was conducted on Rabdosia serra leaf in this work. A new ent-kaurane-type diterpenoid named 6 beta,14 alpha-dihydroxy-1 alpha,7 beta-diacetoxy-7 alpha,20-epoxy-ent-kaur-16-en-15-one, together with 6 known compounds were identified, including parvifolin G, effusanin E. lasiodin, nodosin, beta-sitosterol, and stigmasterol. It was the first time that parvifolin G and effusanin E were found in R. serra. The assay of inhibition activity against HepG-2, MCF-7, and HL-60 cell lines indicated that 10 compounds (including rosmarinic acid, methyl rosmarinate and pedalitin which were isolated previously), except parvifolin G and stigmasterol, exhibited cytotoxicity against the tested turnout cells. The tumour inhibitory effects of ent-kaurane-type diterpenoids (except parvifolin G) were more effective than those of sterols and phenolics. Both 6 beta,14 alpha-dihydroxy-1 alpha,7 beta-diacetoxy-7 alpha,20-epoxy-ent-kaur-16-en-15-one and lasiodin (IC50 < 5 mu M) displayed strong cytotoxicity against the tested tumour cells, indicating the potential for new chemotherapeutic drugs. (C) 2011 Elsevier Ltd. All rights reserved.