QUORUM QUENCHING AND ANTIBACTERIAL ACTIVITY OF SILVER NANOPARTICLES SYNTHESIZED FROM MEDICINAL PLANTS AGAINST METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS (MRSA)

摘要

Objective: The aim of this study was to evaluate quorum quenching and antibacterial activity of silver nanoparticles synthesized from medicinal plants against Methicillin-resistant Staphylococcus aureus (MRSA). Methods: Development of efficient methods for green synthesis of silver nanoparticles using plant extracts has become a major focus ar ea of nanotechnology. The importance of bactericidal nanomaterials is gaining due to the increased resistant strains of bacteria against most potent antibiotics. The discovery of bacterial communication system (Quorum-sensing system), which orchestrate important temporal events during the infection process, has afforded a novel opportunity to ameliorate bacterial infection by means other than growth inhibition. This has promoted research in the well-known bactericidal activity of Ag+ions and Ag-based compounds, including silver nanoparticles (AgNPs). In this study, extracellular biosynthesis of silver nanoparticles was carried out using aqueous extracts of nine different herbal plant leaves for the reduction of aqueous silver ions. The morphologies and structures of the nanoparticles were characterized by transmission electron microscopy, UV-visible spectroscopy and X-ray diffraction. Furthermore, the synthesized AgNPs were evaluavated for quorum quenching and antibacterial activity against MRSA. Results: Among the nine selected medicinal plant leaf extracts Aerva lanata showed rapid reduction (2 min) of silver ions in the solution. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) analysis revealed the nanocrystalline phase of silver with the average particles size ranged from 37-47 nm and has spherical shape. Furthermore the synthesized AgNPs exhibited very effective antibacterial activity against Methicillin Resistance Staphylococus aureus (MRSA). Moreover, the stable silver nanoparticles found to inhibit violacein production, a quorum sensing regulated behavior in Chromobacterium violaceum CV026. Conclusion: The presence of surface active molecules such as flavonoids, terpenoids in the plant leaves extracts stabilize the silver nanoparticles. Furthermore the green synthesized AgNPs established very effective antibacterial and quorum quenching activity against MRSA