Antimicrobial activity of 9-O-acyl- and 9-O-benzoyl-substituted berberrubines

In the course of a structure-activity relationship study on berberrubine de rivatives, a series of compounds bearing 9-O-acyl- (4-6) and 9-O-benzoyl- ( 7) substituents was synthesized with the expectation of increasing the anti microbial activity. One of the berberrubine derivatives, 9-lauroylberberrub ine chloride was the most active against Cram-positive bacteria Enterococcu s faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus luteus, Bacillus subtilis as well as the Gram-negative bacterium Klebsiella pneumoniae in comparison to berberine, the currently used antibiotic in cl inic. This result suggested that the presence of lipophilic substituents of certain structures and sizes might be crucial for the optimal antimicrobia l activity.