Synthesis of bioactive spherical silver nanoparticles with surface plasmon resonance using ethanolic twig extract of Cratoxylum formosum ssp. pruniflorum

Silver nanoparticles (AgNPs) are remarkable nanoparticles among other metal nanoparticles due to their relatively more cost-effective production, smaller size, and more stable against oxidation. Green synthesized AgNPs show the benefits over chemically synthesized AgNPs by their less genotoxicity and less cytotoxicity. In this study, AgNP formation was promoted by the phytochemicals from the ethanolic extract of Cratoxylum formosum ssp. pruniflorum (CFP), acts as the reducing, capping, and stabilizing agent. The prepared AgNPs were characterized using UV–Vis spectrophotometry, electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy, and energy dispersive x-ray spectroscopy. The total phenolic content (TPC) was determined by Folin-Ciocalteu assay. Antioxidant activity was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and ferric-reducing antioxidant power (FRAP) assay. Anti-inflammatory, antibacterial, and anticancer activities were determined using the NF-κB reporter gene assay, WST-8 assay, and neutral red uptake assays, respectively. AgNPs prepared by CFP extract obtained a homogeneous circular-shaped morphology with a size of 27.13 ± 8.35 nm with a zeta potential of −22.44 ± 0.37 mV. The reaction was observed by surface plasmon resonance at 450 nm. The AgNPs were constituted of 77.8% silver abundance and capped with the phytochemicals from CFP extract. AgNPs showed various activities. The TPC of AgNPs was 56.8 ± 2.6 μg gallic acid equivalents (GAE)/mg sample. Antioxidant activity was presented by DPPH scavenging activity with IC50 of 76.9 μg/ml and FRAP value of 0.29 ± 0.019 mmol FeSO4/g sample. Anti-inflammatory activity was illustrated by NF-κB suppression with IC50 of 46.6 ± 1.6 μg/ml. Antibacterial activity was depicted against several strains and species of bacteria with the minimum inhibitory concentrations (MIC) of 50–100 μg/ml against different strains of Staphylococcus aureus (i.e., Newman, R113, LUU17, USA230, POA10, and N315), 200 μg/ml in Escherichia coli, and >400 μg/ml in Serratia marcescens. Anticancer activities were shown by the IC50 of 51.3 ± 0.8, 53.9 ± 0.6, and 111.1 ± 7.0 μg/ml in HCT116, MCF7, and SK-MEL-2 cells, respectively. These findings suggested the potential of AgNPs prepared from CFP extract for multi-purpose pharmaceutical applications.