Development of Green Silver Nanoparticles Formulation against Methicillin-Resistant Staphylococcus aureus

Abstract

Antimicrobial-resistant superbugs are spreading globally at an exponential pace. Methicillin resistant Staphylococcus aureus is one of these superbugs for which antibiotics are required on a priority basis. Natural products from medicinal plants have served as beneficial treatment options since the start of history. After experiencing resistance against synthetic compounds, the trend is shifting to study and utilize these green sources in combination with modern technologies like nanotechnology. Phytosynthesis of silver nanoparticles using medicinal plant extract is an eco friendly approach that can potentially have myriad clinical benefits. In the current study, this green route of nanoparticle synthesis is adopted by using Foeniculum vulgare, Ocimum basilicum and Capsicum annuum leaves to develop a green AgNPs-based formulation against Pakistani clinical isolate of MRSA. A hydroponic system being a healthy and controlled environment was used for plant growth. Extracts from hydroponically grown plants were compared with soil cultivated plants for phytochemical content. The hydroponic system was found to give rapid plant production with comparable phytochemical content to soil grown. Methanolic extracts of plants were obtained and checked for AgNPs’ synthesis potential. Color change of solutions indicated AgNPs synthesis. Synthesized AgNPs were characterized physiochemically by using UV-vis spectroscopy, FTIR, DLS and SEM analysis. Test results depicted the synthesis of nanosized, spherical particles with the capping of plant material. Biological activity was estimated by qualitative phytochemical testing. Moreover, enhanced in vitro anti-MRSA potential was observed by MIC and MBC values. MIC of FE NPs was 0.625mg/ml and MBC 2.5mg/ml. MIC and MBC values for BE NPs were found to be 0.156 mg/ml and 0.625mg/ml respectively. MBC value for CE NPs was similar to BE NPs but MIC was 0.312mg/ml. These inhibitory and bactericidal concentrations were lesser than the plant extracts alone and controls, supported the enhanced anti-MRSA potential of AgNPs. Nanoparticles from either source were loaded in a polyvinyl pyrrolidone and ethylene cellulose hydrogel formulation and applied to MRSA-infected wounds on mice skin. Infection elimination and skin reepithelization were observed in H&E stained slides of biopsy samples. This study suggests that hydroponic plant cultivation is equally potent to soil cultivation for the development of green AgNPs-based ointments with successful wound healing and infection elimination potential on mouse skin caused by Pakistani clinical isolate of MRSA. Synthesized AgNPs can be evaluated for other routes of administration and against other resistant strains of XI bacteria. Developed formulations can be evaluated for their pharmacotherapeutic benefits in clinical trials.