Cytotoxic activity of alkaloids isolated from Stephania rotunda [corrected].

Three major alkaloids: cepharanthine (1), tetrahydropalmatine (2) and xylopinine (3) isolated from Stephania rotunda tuber were investigated for their cytotoxic activity in a panel of human cancer cells (HT29, LS174T, SW620 and HepG2) using MTT assay. In the present study, cepharanthine (1) exerted potent cytotoxicity against colon and hepatoma cancer cell lines with IC(50) values between 2.4 and 5.3 microM while tetrahydropalmatine (2) and xylopinine (3) displayed weak cytotoxicity. In addition, the mutagenic activity of cepharanthine (1) was investigated using a modified liquid incubation technique of the Salmonella/microsomal assay. This alkaloid (1) was found to be non-mutagenic for doses up to 8.2 microM.