Green Synthesis of Silver Nanoparticles Using the Leaf Extract of <I>Pentaclethra macrophylla</I>: Characterization and Evaluation of Their Antimicrobial Activities

Abstract

Antimicrobial resistance has become a pervasive medical issue that necessitates immediate attention. Thus, research for better substitutes has become of great importance. Recent studies of the silver nanoparticles (SNP) have demonstrated that they possess promising activities as a bactericidal agent against both Gram-positive and Gram-negative bacteria and also as a fungicidal agent without toxicity to humans. The aim of this current study was determining the antimicrobial property of green synthesized nanoparticles of Pentaclethra macrophylla leaf extract. The plant extract was prepared by decoction and green synthesis was carried out. Characterization of the green synthesized silver nanoparticles were carried out using spectroscopic techniques such as UV-Visible spectrometry, Fourier Transform Infrared spectrometer (FT-IR), and Dynamic Light Scattering technique (DLS). Antimicrobial susceptibility testing was done using the agar dilution method with several clinical isolates of the test microorganisms. The UV- Visble spectrum displayed a peak between 418-430 nm. The FT-IR results showed the presence of phytochemicals in P. macrophylla. The size distribution histogram of dynamic light scattering (DLS) indicates that the sizes of these silver nanoparticles range from 34.57-134.70 nm with an average of 131.29 nm. Additionally, the anti-microbial sensitivity testing showed an inhibitory effect of silver nanoparticles. The minimum inhibition concentrations (MIC) were at 8 µg/mLfor Salmonella typhi, 9 µg/mL for Escherichia coli, 5 µg/mL for Bacillus subtilis, 8 µg/mL for Staphylococcus aureus, 9 µg/mL for Candida albicans, and 10 µg/mL for Aspergillus niger. These outcomes denotes the promising antimicrobial activity of silver nanoparticles synthesized using the aqueous leaf extract of P. macrophylla.