The Antibacterial Mechanism Of Houttuyfonate Homologues Against G~+ Bacteria

To evaluation antibacterial activity of houttuyfonate homologues(HOU-Cn,n=8,10,12),bacteria such as Staphylococcus aureus and Bacillus subtilis were used as target microbes.The Bacillus subtilis was used as microbes model to research antibacterial mechanism for G~+ bacteria.The experiment of paper disc method showed that Staphylococcus aureus and Bacillus subtilis were sensitive to HOU-Cn,but Bacillus subtilis was more sensitive.Further test with Staphylococcus aureus and Bacillus subtilis by tuber dilution method indicated that the minimum antibacterial concentration(MIC)of HOU-C8,HOU-C10 and HOU-C12 for Staphylococcus aureus were:50mg/l,50mg/l and 25 mg/l;and for Bacillus subtilis were 35mg/l,20mg/l and 20mg/l.MBC for Staphylococcus aureus were:160mg/l,80mg/l and 55mg/l;and for Bacillus subtilis were 150mg/l,70mg/l and 50mg/l,respectively.Compared with the result of surface activity study,it included that the antibacterial activity of HOU-Cn was proportional to their hydrophobic activity.The results of HOU-Cn on the membrane lipid fluidity experiment showed that no significant change in membrane lipid fluidity of Bacillus subtilis;the fluorescence experiments indicated that HOU-Cn directly bound to membrane proteins of G~+ bacteria by hydrophobic interaction,and made the conformation of membrane protein change;SDS-PAGE electrophoresis and GC found that there was significant.change in protein and fat acid synthesis.At the same time,the effects of HOU-Cn on cell membrane protein conformation,protein and fatty acid synthesis increased with the length of carbon chain increasing.It speculated that the antibacterial activity of HOU-Cn was mainly related to the changes in the conformation of those proteins caused by HOU-Cn,leading key enzyme to lose its function and effect protein and fat acid synthesis.With HOU-Cn concentration increased,the bacteria would die.