Total Synthesis of Kuwanons A and B and Discovery of Their Antibacterial Mechanism.

Kuwanons A ( 1 ) and B ( 2 ) are two natural prenylated flavones isolated from the root bark of Morus alba L. In this study, the first total syntheses of kuwanons A ( 1 ) and B ( 2 ) were achieved from a common intermediate with overall yields of 6.6% and 11.6%, respectively. Kuwanon B ( 2 ) exhibited antibacterial activity against Gram-positive bacteria and concentration-dependent bactericidal activity against Staphylococcus aureus bacteria. Preliminary mechanism of action studies suggested that this compound killed bacteria rapidly by disrupting bacterial membrane integrity.