Eco-friendly Synthesis of Silver Nanoparticles using Bignay (Antidesma bunius) Leaves for Antibacterial Application

Abstract

Background:: Foodborne pathogenic bacteria continue to become a global concern despite the advancements in food packaging technology. Silver nanoparticles (AgNPs) are widely studied in the field as they exhibit desirable inhibitory properties against foodborne pathogens. AgNPs are conventionally synthesized by toxic chemical and physical means; hence, there is a need to seek environmentally safe alternative routes for producing AgNPs. Objective:: The study aimed to synthesize AgNPs using bignay (Antidesma bunius) leaf extract and assess its antimicrobial activity against the common foodborne pathogens S. aureus and E. coli. Methods:: Bignay leaf extract was characterized using total phenolic content (TPC) assay and 2,2- Diphenyl-1-picrylhydrazyl (DPPH) assay. AgNPs were produced under optimized pH, temperature, and incubation time and were characterized using UV-Vis spectroscopy, Fourier Transform Infrared spectroscopy, and Transmission Electron Microscopy. The antimicrobial activity of AgNPs was evaluated against S. aureus and E. coli using the Resazurin Microtiter Assay (REMA). Results:: Bignay leaf extract exhibited a total phenolic content of 0.315 ± 0.015 mg GAE/mg extract and an IC50 of 36.36 ± 0.003 μg/mL, which suggests its good reducing properties. The AgNPs synthesized under reaction conditions of pH 7, 45 ºC, and 30 min showed SPR peaks in the range of 412- 426 nm. Particles were spherical with an average size of 23.72 ± 7.30 nm. FTIR analysis revealed that the phenolic compounds in the extract capped the resulting nanoparticles. AgNPs demonstrated superior inhibitory activity against S. aureus and E. coli with MIC90 values of 2.90 ± 0.03 and 3.08 ± 0.004 μg/mL, respectively. Conclusion:: The study was able to develop a green approach for the synthesis of AgNPs with antibacterial properties using bignay leaf extract.