Antimicrobial Activity of Hydrophobic Xanthones from Cudrania cochinchinensis against Bacillus subtilis and Methicillin‐Resistant Staphylococcus aureus

Abstract Ten xanthones with one or two isoprenoid groups and a prenylated benzophenone isolated from roots of Cudrania cochinchinensis (Moraceae) were tested for their antimicrobial activities against Bacillus subtilis and methicillin‐resistant Staphylococcus aureus (MRSA). Among these compounds, gerontoxanthone H exhibited considerable antibacterial activity against B. subtilis ( MIC =1.56 μg/ml). Four xanthones, gerontoxanthone I, toxyloxanthone C, cudraxanthone S, and 1,3,7‐trihydroxy‐2‐prenylxanthone, showed weak antibacterial activity against the bacterium ( MIC s=3.13–6.25 μg/ml). These compounds also exhibited similar MIC values against methicillin‐sensitive S. aureus , MRSAs, and Micrococcus luteus.