Anti-virulence activities of biflavonoids from Mesua ferrea L. flower

Based on the anti-virulence activity on Salmonella, the ethyl acetate extract (EAE) of Mesua ferrea flower was investigated for its chemical constituents. Ten purified compounds were identified and assayed for their inhibitory activity against Type III secretion system (T3SS) by polyacrylamide gel electrophoresis (SDS-PAGE) and Western blots experiments. We found the biflavonoids, rhusflavanone and mesuaferrone B, exhibited inhibitory effects on the secretion of Salmonella pathogenicity island 1 (SPI-1) effector proteins (SipA, B, C and D) without effecting the bacterial growth. In addition, 5, 6, 6'-trihydroxy-[1,1'-biphenyl]-3,3'-dicarboxylic acid (6) is a new natural product from M. ferrea flower.