Antimicrobial activity of some pentacyclic triterpenes and their synthesized 3-O-lipophilic chains.

The major metabolites of Diopsyros melanoxylon viz. amyrins and ursolic acid and their lipophilic 3-O-fatty acid ester chains (C12-C18), which are synthesized now under mild esterification conditions in excellent yields (80-95%), were evaluated for their antimicrobial activity against a series of Gram positive and Gram negative bacteria. Significantly these compounds were found to exhibit potent activity against Gram negative bacteria Pseudomonas syringae (ATCC #13457) and fairly good activity against Gram positive bacteria, Bacillus sphaericus (ATCC #14577) and Bacillus subtilis (ATCC #6051).