Antibacterial activity of stilbene oligomers against vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) and their synergism with antibiotics

Two resveratrol trimers, gnemonol B isolated from Gnetum gnemon and gnetin E obtained from the Gnetum species, were found to exhibit strong antibacterial activities against vancomycin-resistant Enterococci (VRE) and methiclllin-resistant Staphylococcus aureus (MRSA). The MIC values of gnemonol B against five strains of VRE and nine strains of MRSA were 12.5 and 6.25 μ g/ml, respectively. The MIC values of gnetin E against five strains of VRE and nine strains of MRSA ranged from 12.5 to 25 μ g/ml. These compounds also showed synergistic effects when used in combination with commercially available antibiotics according to the evaluation method using FIC indices. These findings suggested that the application of the test compounds alone or in combination with antibiotics might be useful in controlling and treating VRE and MRSA infections.