FLAVANONES WITH POTENT ANTIBACTERIAL ACTIVITY AGAINST METHICILLIN-RESISTANT STAPHYLOCOCCUS-AUREUS

With the therapeutic concept of using the defensive ability of plants against microbial infections, phytoalexin, an antimicrobial phytochemical was studied for its ability to inhibit the growth of methicillin-resistant Staphylococcus aureus (MRSA). Extracts from Sophora exigua (Leguminosae) were fractionated by serial chromatography and the anti-MRSA activity of each fraction was determined by the agar-plate method. Among the active isolates, 5,7,2',6'-tetrahydroxy- 6-isoprenyl-8-lavandulyl-4'-methoxyflavanone (exiguaflavanone D) completely inhibited the growth of all the MRSA strains examined at the concentration of 1.56-6.25 mu g mL(-1), and 5, 2',6'-trihydroxy-8-lavandulyl-7-methoxy-flavanone (exiguaflavanone B) inhibited at a concentration of 50 mu g mL(-1). This former compound is expected to be a phytotherapeutic agent for MRSA infections as an alternative to conventional antibiotics with unwanted side-effects or the appearance of antibiotic-resistant bacteria.