New antimicrobial flavanones from Physena madagascariensis

Two new flavanones (1 and 2) with antibacterial activity were isolated from the methanolic extract of the dried leaves of Physena madagascariensis usi ng activity against Staphylococcus aureus to guide the isolation. A third f lavonoid, a flavanone dimer linked by a methylene group (3) was also isolat ed and proved to be inactive. The structures of 1 and 2 were established pr imarily from NMR studies, while that of 3 required more extensive mass spec trometric analysis. All three flavanones had lavandulyl units in the limone ne form. Flavanones 1 and 2 were active against several bacteria at concent rations as low as 4 mu M.