Plant-mediated synthesis of silver nanoparticles using mangosteen pericarp extract and their antimicrobial potential

Abstract

Silver nanoparticles (AgNPs) were synthesized using mangosteen pericarp ethanolic extract (MPEE) as a source of bioreductants and their antimicrobial activity against common foodborne pathogens was evaluated. Characterization of MPEE was conducted using phytochemical screening, total phenolic content analysis, and DPPH (antioxidant) assay. Synthesis AgNPs and optimization studies were monitored using UV-Vis spectrophotometry. Transmission electron microscopy was used to characterize the AgNPs, and resazurin microtiter assay was used for antimicrobial testing. Alkaloids, flavonoids, saponins, quinones, anthraquinones, and tannins were confirmed present in the extract. TPC and IC50 of MPEE were 0.192 mg GAE/mg extract and 0.277 mg/mL, respectively. A surface plasmon resonance (SPR) peak within 450-403 nm confirmed the formation of AgNPs. At pH 7, the optimum reaction conditions were 45 °C and 3 h. Meanwhile, at pH 9, the optimum reaction conditions were 27 °C and 0.5 h. The sizes of nanoparticles synthesized at pH 7 and pH 9 were 13-35 nm and 7-38 nm, respectively. The minimum inhibitory concentration (MIC90) of AgNPs produced at pH 7 were 1.45, 2.81, and 2.93 ug/mL for S. aureus, E.coli, and B. cereus, respectively. For AgNPs synthesized at pH 9, the MIC90 were 2.93, 3.02, and 5.24 ug/mL, for the same microorganisms, respectively. MPEE was able to successfully synthesize AgNPs. Compared to chloramphenicol, AgNPs exhibited better antimicrobial activity, which can address the growing concern of drug resistance in certain pathogenic microorganisms. Furthermore, the use of MPEE provides a green and sustainable alternative to synthesizing AgNPs.