Preliminary Study On Inhibition Of The Staphylococus Aureus Sortase A By Rutin

Staphylococcus aureus (S.aureus) is a zoonotic pathogenic Gram-positivebacterium, causing such purulent infections as minor skin infections and endocarditis,meningitis, arthritis and osteomyelitis, posing a serious threat to human health andproperty security. It seems to be a new chapter for the treatment of bacterial infectionswith the discovery of penicillin and other antibiotics, and they made importantcontributions to prolong human life indeed.However the antibiotic-resistant strainswere isolated rapidly due to the massive unregulated use of antibiotics, especially theemergence of methicillin-resistant Staphylococcus aureus (MRSA). The first MRSAwas isolated in1961, then disseminated worldwide during only ten years.MRSAcasued the majority of nosocomial infections, and the incidence of MRSA infectionwas increasing throught the world. In addition, MRSA are the multidrug resistancestrains that are resistant to many, if not all, antibiotics currently in clinical use. It hasbeen described previously that the strains with intermediate or full resistance tovancomycin which was once considered last resort therapies for MRSA were isolated.With the choice of drugs less, it is imperative to identify the novel drug targets anddevelop the inhibitors that can be used for therapy of infections.Drugs targeting virulence is an alternative approach to treat infections due tobacteria.As therapeutic targets,it would be reduced the pathogenicity with inhibitionof the virulence factors rather than eliminated such as classicalantibiotics.Therefore,the selective pressure for viability of mutants potentiallycarrying a resistance genotype shoud be decreased. Sortase which catalyzes thepeptidoglycan cell wall anchoring reaction of virulence factors, has been proposed tobe a universal target for therapeutic agents against Gram-positive bacteria, and there isno effect on growth of bacteria without sortase.The inhibitors of the S.aureus SrtA hasbeen concerned and studied over the past few years. Traditional Chinese medicinesare unique resource of drugs material for treatment of disease.In this study, S.aureusSrtA was cloned and espressed in order to identify the inhibitors from the antipyreticand detoxicate plants by FRET (fluorescence resonance energy transfer), and then5 compounds had been identified.Rutin as an inhibitor for SrtA have not reported in anyreview.Rutin is widely distributed in nature which belongs to the flavonoids. It hasvarious biological effects, including anti-oxidative, anti-inflammatory, anti-tumor andanti-platelet characteristics.Rutin showed a good inhibitory activity against SrtA byFRET. The characteristics in S.aureus were assessed by clumping assay andfibrinogen/fibronectin-binding assay. Furthermore, we observed the influence for SrtAexpression of S.aureus with rutin by Western-blot. The results showed that theproduction of SrtA was not declined, but the S.aureus didn’t clump fibrinogen owingto the inhibition of SrtA by rutin. The result of fibrinogen/fibronectin-binding assayshowed dose-dependent inhibition effects of rutin on adhesion of S.aureus. Wild-typetreatment with rutin (64μg/mL) inhibited S.aureus binding by72.03%and65%onfibrinogen-and fibronectin-coated plates. The result suggested that as a potentialinhibitor, the detailed mechanism should to be studied further. In summary, the studyon rutin provides a theoretical basis for anti-infective therapy in research anddevelopment of new medicine.