Investigation of the antibacterial activity of 3-O-octanoyl-(-)-epicatechin

摘要

To measure antibacterial activity of the semi-synthetic flavonoid 3-O-octanoyl-(-)-epicatechin and investigate the mechanism of action. MICs determined by the broth microdilution method were 50 og mlp# for o-lactam sensitive and resistant Staphylococcus aureus, and 100 og mlp# for vancomycin sensitive and resistant enterococci. In time-kill studies, 100 og mlp# 3-O-octanoyl-(-)-epicatechin reduced colony forming unit numbers of antibiotic sensitive and methicillin-resistant Staph. aureus below detectable levels within 120 min. Bacterial aggregation was not observed when cells exposed to 3-O-octanoyl-(-)-epicatechin were examined by light microscopy. It was also shown that 50 og mlp# 3-O-octanoyl-(-)-epicatechin is capable of reducing colony forming unit numbers of high cell density Staph. aureus populations by 80-fold within 60 min incubation, and inducing leakage of 50% of their internal potassium within just 10 min. 3-O-Octanoyl-(-)-epicatechin is active against Gram-positive bacteria, has bactericidal activity against both antibiotic sensitive and resistant strains, and is likely to exert its primary antibacterial effect by damaging the cytoplasmic membrane. 3-O-Octanoyl-(-)-epicatechin has significant antibacterial activity and additional structural modification and/or formulation studies may allow this to be potentiated.