Phytoassisted synthesis of biogenic silver nanoparticles using Vernonia amygdalina leaf extract: characterization, antibacterial, anti-inflammatory, and acute toxicity profile

The increasing rate of antimicrobial resistance and pathological consequences associated with long-term use of available anti-inflammatory drugs justifies the urgent need to discover and rationally design new effective antimicrobial and anti-inflammatory drugs. This study reports the antibacterial, anti-inflammatory, and acute toxicity profile of Vernonia amygdalina leaf extract-mediated silver nanoparticles (VA-AgNPs).The VA-AgNPs were synthesized by mixing Ag+ ions with aqueous leaf extract from Vernonia amygdalina and then characterized using UV-visible spectrophotometry (UV-Vis), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). An antibacterial study on Escherichia coli strains, carrageenan-induced rat paw edema, and oral acute toxicity assays were performed. The change in color from light brown to dark brown showed the formation of VA-AgNPs which was further confirmed by the surface plasmon resonance picked between 400 and 450 nm on the UV-Vis spectrum. Synthetic stability studies revealed an increase in VA-AgNPs formation at basic pH and with increasing reactant quantities. The X-ray pattern showed nanocrystalline particles of Ag and AgCl of 13, and 18 nm mean sizes, respectively. SEM images depicted aggregates of spherical shape. The synthesized VA-AgNPs inhibited Escherichia coli growth with a minimum inhibition concentration of 0.125 mg/mL and rat paw edema with a maximum inhibition percentage of 96% at a dose of 0.4 mg/kg body weight. The oral administration of VA-AgNPs was associated with no toxicity sign, supporting their use for the development of new effective antibacterial and anti-inflammatory drugs.