Anti-tumor promoting effects of multiflorane-type triterpenoids and cytotoxic activity of karounidiol against human cancer cell lines

Forty-nine multiflorane-type triterpenoids consisting of 11 compounds isola ted from the seeds of Trichosanthes kirilowii (Cucurbitaceae) and 38 of the ir derivatives have been evaluated for their inhibitory effects on Epstein- Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate in Raji cells as a primary screening t est for anti-tumor promoters. All of the compounds tested showed an inhibit ory effect against EBV-EA activation, and among which 43 were revealed to p ossess remarkable activity with potencies either comparable to or stronger than that of glycyrrhetic acid, a known natural anti-tumor promoter. Their structure-activity relationship is discussed. Evaluation of the cytotoxic a ctivity of karounidiol (27) against human cancer cell lines exhibited cytot oxicity especially against a human renal cancer. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.