Antioxidant, antimicrobial, and anticholinesterase activities of A. nitida leaf extract mediated silver nanoparticles

Alnus nitida-derived silver nanoparticles (An-AgNPs) were fabricated using the leaf extract of this medicinal plant, selected for its rich phytochemical profile and strong reducing potential, through a green synthesis approach. The synthesized nanoparticles were previously characterized using standard physicochemical techniques, confirming their nanoscale size, stability, and functional groups responsible for reduction and capping. An-AgNPs and leaves extract were evaluated for their antioxidant (DPPH and ABTS), anti-bacterial, anti-cholinesterase (acetylcholinesterase (AChE), butyrylcholinesterase (BChE)), and anti-diabetic (α-amylase and α-glucosidase) potentials. An-AgNPs showed potent DPPH and ABTS scavenging activities with IC50 values of 125 and 115 µg/mL, followed by leaves extract with IC50 values of 930 and 400 µg/mL, respectively. An-AgNPs also exhibited potential inhibitory activities against AChE, BChE, amylase, and glucosidase with IC50 values of 63, 65, 160, and 65 µg/mL, respectively, whereas the leaves extract exhibited IC50 values of 70, 100, 215, and 235 µg/mL, respectively. The micro-titre plate-based assay of An-AgNPs showed excellent antibacterial activity against both gram-positive bacteria, Staphylococcus aureus (93.76%), Bacillus subtilis (88.35%), and gram-negative bacteria, Escherichia coli (87.67%), Pseudomonas aeruginosa (91.65%), Salmonella typhi (92.28%). The findings of the study demonstrate that An-AgNPs possess significant multifunctional bioactivities and highlight their potential for biomedical and pharmaceutical applications.