Characterization and Antimicrobial Activity of Silver Nanoparticles Biosynthesised from Some Medicinal Plant Extracts of Benin

The use of plant extract as a bio reductant for the synthesis of silver nanoparticles has attracted the attention of several researchers due to its rapid, non-pathogenic and economical protocol. This innovative approach in Benin offers an alternative in medical therapy face of antimicrobial resistance, which is a real public health problem. This study aims to characterize biosynthesized silver nanoparticles (AgNPs) and evaluate the antibacterial activity of synthesized silver nanoparticle from the aqueous extracts of the leaves of <i>Caesalpinia bonduc, Dialium guineense, Momordica charantia, Moringa oleifera, Pavetta corymbosa, Psidium guajava</i>, derived from the flora of Benin. The leaves of plants was collected, authenticated and extracted by water. The synthesized AgNPs by the aqueous extracts were characterized using UV-Vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) analysis. These characterization techniques allowed to determine the size, shape, crystalline nature, morphology, and the functional groups responsible for the reduction and stabilization of the nanoparticles. The antibacterial activity of AgNPs was determined against six different nosocomial bacteria by the standard disk diffusion method. The results confirmed the successful biosynthesis of AgNPs from the leaves of the six plants as indicated by a colour change from light yellow to brown and grey black. The UV-Vis spectroscopic analysis presented a surface plasmon resonance spectrum with absorption maxima ranging from 340 to 500 nm. XRD analysis demonstrated that the synthesized AgNPs possess a crystalline structure from 1 to 2 μm. In addition, the antimicrobial activities of AgNPs synthesized as reducing agents and stabilizers were investigated against nosocomial bacteria, which are nosocomial infectious agent. Collectively, the findings from this study clearly indicate that the aqueous extracts of the six plants have significant potential for the biosynthesis of silver nanoparticles. The bioactive compounds in the plant extracts were effective in synthesizing AgNPs, and this biological efficiency suggests the potential for incorporating these biosynthesized silver nanoparticles into food and pharmaceutical products.