Preparation Of Protoanemonin And Its Derivatives And Study On Its Effects On QS-regulated Virulence Factors Production By Pseudomonas Aeruginosa

Objective: To prepare protoanemonin and its derivatives, and study its effect on Quorum Sensing regulated virulence factors production by Pseudomonas aeruginosa,to test its effect as QS-inhibitor and try to demostrate the mechanism of its anti-infection activity.Method: Starting from sucrose, protoanemonin had been prepared via hydrolysis, intramolecular esterification, bromine addition, elimination of bromide hydrogen; 4-bromo-5-methyl bromide-2(5H)-furanone (furanone C-30) had been prepared via hydrolysis, bromine substitution and reaction with concentrated sulfuric acid. Preparation of 4-(4-chlorobenzyl)-5-methylene-2(5H)-furanone had been tried via hydrolysis, intramolecular esterification, Stobbe condensation and cyclization. All the structures of intermediates and target compounds were verified by UV, IR and 1H-NMR. With furanone C-30 as a positive control group, the effect of protoanemonin on growth of the standard strain of Pseudomonas aeruginosa PAO1 was assessed, and in concentrations which had no or only little effect on growth of PAO1, its effects on extracellular virulence factors (pyocyanin, protease and elastase) production by PAO1 were also evaluated.Results: Protoanemonin, anemonin, furanone C-30 and intermediates were confirmed by UV, IR and 1H-NMR. Although preparation of 4-(4-chlorobenzyl)-5-methylene-2(5H)- furanone had not been finished yet, its intermediates had already been comfirmed. Protoanemonin in concentration used in this study had no or only little effect on growth of PAO1, but attenuate bacterial virulence. Experiment data indicates that protoanemonin can reduce the production of pyocyanin, protease and elastase, with a dose-dependent manner, although weaker than furanone C-30.Conclusion:Similar to furanone C-30, protoanemonin could inhibit the expression of three virulence factors (pyocyanin, protease and elastase) regulated by QS system of PAO1. It is possible that protoanemonin has QS-inhibitor activity, and inhibit the expression of virulence factors and attenuate virulence via blocking QS system might be the mechanism of its anti-infection activity.