Screening Of Quorum Sensing Inhibitors And Study On QSI Activity Of Oridonin In Pseudomonas Aeruginosa

ObjectiveClinical treatment was always plagued with bacterial infections.The abuse of antibiotics caused that multiple drug-resistant bacteria were becoming increasingly prominent.Currently,searching new targets and researching new antibacterial medicine will become the future trend of pharmacy development.Quorum sensing inhibitors inhibit virulence factor and biofilm by interfering autoinduce signaling molecules in quorum sensing system.In the studies,15 kinds of traditional Chinese medicines have been screening QSI for Pseudomonas aeruginosa quorum sensing system.Oridonin is found with QSI activity and explored the mechanism.MethodsChromobacterium violaceum CV026 has been used as indicator strains.In order to obtain potential quorum sensing inhibitors,15 kinds of traditional Chinese medicines are screened by indicator strains and violacein quantitative estimation.The influence of medicine extracts on pyocyanin production,rhamnolipid production,lasA protease activity,lasB elastase activity and biofilm formation are determined in Pseudomonas aeruginosa PA01.In order to exclude the intervene of noneffective ingredient,the influence of medicinal ingredient on virulence factor and biofilm are determined furtherly.Finally,the expression level of transcription regulator,lasR gene and rhlR gene,are determined by RT-qPCR.ResultsScreening with Chromobacterium violaceum CV026,Rabdosia rubescens alcohol extract can inhibit 77.2% violacein production in minimum inhibitory concentration(MIC).In Pseudomonas aeruginosa virulence factor and biofilm assay,Rabdosia rubescens alcohol extract can inhibit 25.9% pyocyanin production,45.6% rhamnolipid production,31.6% lasA protease activity,54.8% lasB elastase activity and 31.7% biofilm formation in MIC.Oridonin,a medicinal active ingredient in Rabdosia rubescens,is selected for experiment.Oridonin can inhibit 70.7% violacein production,39.4% pyocyanin production,60.7% rhamnolipid production,30.0% lasA protease activity,50.3% lasB elastase activity and 48.4% biofilm formation in MIC.In addition,Oridonin can inhibit virulence factor and biofilm by down-regulating the transcription regulator in Pseudomonas aeruginosa.ConclusionOridonin is a kaurene diterpenoid natural compound.The findings of the effects in PA01 model throw light on the antiinfective property of the oridonin in MIC.The above property could be exploited in developing the oridonin as an antipathogenic agent alone or in combination with antibiotics against drug resistant pathogenic bacteria.