Novel C-ring analogs of ursolic acid: synthesis and cytotoxic evaluation.

Ursolic acid (1), a natural pentacyclic triterpenic acid, afforded a variety of ring-C transformed products (5-11) when treated with N-bromosuccinimide under the influence of a range of protective groups and solvents. The synthesized compounds have been evaluated for cytotoxic activity against prostate PC 3, leukemia THP 1, cervical Hela and lung A-549 cancer cell lines. Among the tested analogs, compounds 5, 8, 9 and 10 showed potent activity against PC 3, THP 1 and Hela cell lines. Especially, compound 10 showed enhanced activity against the Hela cell line than the parent compound. Compounds 5, 8 and 9 showed comparable activities against PC 3 and THP 1 cell lines.