Enhanced antibacterial effect of natural tannin stabilized silver nano particles against human pathogens: A target toward FtsZ proteins

Tannins are the polyphenolic group of plant compounds having strong antimicrobial potential. Research on human pathogens using silver nanoparticles for antimicrobial purposes has opened up new possibilities in nanomedicine. The present study was concerned with combining the effectiveness of the two by the green synthesis of silver nanoparticles with plant tannin. Synthesis of silver nanoparticles was done based on the tannin content of the selected plants. Characterization of the synthesized nanoparticles has been performed through UV-VIS, FTIR spectroscopy, Zeta potential, XRD analysis and FEGSEM imaging. The antibacterial potentiality of the nanoparticles was checked against two most susceptible bacteria Staphylococcus epidermidis and Salmonella typhi . Among the studied plants, Phyllanthus emblica showed highest tannin content and best bactericidal properties. The nanoparticles synthesized with P. emblica showed the highest zone of inhibition against the studied bacteria. An in-silico comparative molecular docking study of the bioactive compounds from the selected plants was performed against the FtsZ protein of S. epidermidis and YfdX protein of S. typhi. Three compounds namely Isocorilagin,1(β), 6-di-o-galloylglucose and Hamamelitannin appeared as the best inhibitors of the said proteins and among them, Isocorilagin, a natural tannin showed the best docking score of -10.2 Kcal/mol with FtsZ protein. Further molecular dynamics simulation studies of the FtsZ protein-Isocorilagin complex support its stability indicating Isocorilagin as the natural inhibitor of the pathogenic bacterial protein FtsZ. These results concluded that synthesis of nanoparticles with plant tannin is a cost effective green approach and the synthesised nanoparticles appear as efficient antimicrobial agent.