Inhibitory effects of Green synthesized Senna alexandrina silver nanoparticles (SAAgNPs) on Escherichia coli DnaK

Abstract

Plant extracts have garnered considerable interest in the environmentally friendly and economically viable production of silver nanoparticles (AgNPs) through their application in green synthesis. However, Plant-derived nanoparticles may potentially have unique physicochemical characteristics. This study is significant in that it contributes to the understanding of the effects of AgNPs on the functional and structural integrity of the heat shock protein DnaK. The research presents an improved synthesis process for silver nanoparticles (AgNPs) from the Senna alexandrina leaf extract. In addition to evaluating the synthesized AgNP's physicochemical characteristics, the research also examines their effect on the functional activity of E. coli DnaK. During synthesis, the color change from light yellow to dark brown was observed within 30 minutes after the addition of 3 ml of S. alexandrina leaf extract to 1 mM of silver nitrate. A surface plasmon resonance peak at 420 nm revealed by ultra-violet spectroscopy was used as additional confirmation that AgNP had formed. The synthesized SA-AgNPs were characterized using UV- VIS spectrophotometry, FTIR, and SEM analysis. Furthermore, heat shock proteins (Hsp) are cellular and stress-induced proteins. With respect to this, it is anticipated that the Hsp can also interact with AgNPs transported into cells and/or the circulation system. The present study was intended to investigate the effects of synthesized silver nanoparticles (AgNPs) using locally- sourced leaf extracts of S. alexandrina on E. coli DnaK. In this study, AgNPs were synthesized using the green synthesizing method by the reduction of silver nitrate into nano-sized silver nanoparticles (AgNPs) inactivated concurrently, which was capped with the phytochemicals of S. alexandrina . FTIR, UHPLC-qTOF-MS, investigated the functional groups present in plant extract to identify the compounds responsible for reducing silver ions. Altogether, findings from this study suggest that DnaK is highly involved in E. coli cytoprotection against AgNPs. In conclusion, both the effect of AgNPs on DnaK stability to heat stress and function in suppressing MDH aggregation were investigated. More importantly, it was also observed that AgNPs can suppress heat-induced aggregation of MDH and consequently stimulate ATPase activity of DnaK. In silico docking studies revealed promising binding affinities of specific metabolites in relation to key proteins (DnaK and its co-chaperones) involved in bacterial survival.