Green synthesis of silver nanoparticles using water extract of panchavalkala and its antimicrobial activity in - vitro

Abstract

‘Panchavalkala’ is a combination of water extracts of five barks of medicinal plants widely used for treating wounds in ayurvedic medicine. Three different combinations are commonly used as Panchavalkala in Sri Lanka. Recently, the synthesis of silver nanoparticles (Ag-NPs) using various plant extracts has become popular due to their cost-effectiveness, affordability, effectiveness, and eco-friendliness. Therefore, the objective of this study was to synthesize silver nanoparticles using the three different combinations of Panchavalkala and to assess their antimicrobial activity (AMA) against some common wound pathogens. Three different Panchavalkala combinations were prepared using barks of each plant concentrating into 8:1 by boiling; named as A (F. bengalensis, F. racemosa, F. religinosa, F. arnottiana, G. quaesita), B (F. bengalensis, F. racemosa, F. religinosa, T. populnea, A. indicum) and C (F. bengalensis, F. racemosa, F. religinosa, C. cainito, G. quaesita). Ag -NPs were synthesized by mixing 10 ml of each filtered extract with 90 ml of 1 mM aqueous silver nitrate. Synthesis of Ag-NPs was confirmed by the colour change, UV-visible absorbance and scanning electron microscopy (SEM). Screening of AMA was carried out using the agar well diffusion assay on standard isolates of Escherichia coli, Pseudomonas auregenosa, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus and Candida albicans as well as clinical isolates of methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA). Ag-NPs synthesized from each combination of Panchavalkala showed antimicrobial effects against all the tested microorganisms. Ag-NPs synthesized from samples B and C showed significantly higher effects than sample A against clinical isolates and standard of MRSA and C. albicans (p<0.0001). Sample B showed significantly higher effects against clinical isolates and standard MSSA (p<0.0001) than samples A and C. In conclusion, Ag-NPs synthesized from the above three combinations of Panchavalkala were effective against all the tested microorganisms. Further studies are recommended to explore the molecular-level interactions such as drug antagonism, additivism, and synergy of Panchavalkala and Ag- NPs.