Enhancement of anti-bacterial and anti-tumor activities of pentacyclic triterpenes by introducing exocyclic α,β-unsaturated ketone moiety in ring A

Ursolic acid, oleanolic acid, glycyrrhetinic acid, and betulinic acid, the representatives of pentacyclic triterpenes, were modified by introducing 2-methylene-3-oxo group as exocyclic α,β-unsaturated ketone moiety in ring A. The anti-bacterial and anti-tumor activities of these derivatives were assayed by comparing with the parent compounds. Results indicated that pentacyclic triterpenes carrying 2-methylene-3-oxo group in the ring A exhibited a significant improvement in anti-bacterial activity that was limited to Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis. The four derivatives also showed an increased cytotoxicity against leukemia, lung, and breast cancer cell lines in a dose-dependent manner in vitro. U2 and O2 compounds showed strong apoptotic activities to lung carcinoma cell lines. The results for the first time provided scientific evidence for improvement of anti-bacterial and anti-tumor activities of pentacyclic triterpenes using derivatives of these compounds.