Synthesis and anti-tumor activity of derivatives of ursolic acid in vitro

A series of ursolic acid derivatives were synthesized by the introduction of 4-chloroindole compounds at A ring and esterification and amidation at C-28 position, which structures were characterized by ¹H NMR, MS and etc. The cytotoxic activity of derivatives was evaluated against HepG2 and SGC7901 cells in vitro by MTT assay, in which paclitaxel and adriamycin were used as a positive control. The results indicated that all of derivatives can inhibit cell proliferation in HepG2 and SGC7901 cells with a better activity than ursolic acid. Especially, the compounds 6 and 12 showed significant antitumor activity comparable to the paclitaxel. The compounds are worthy to be studied further.