Eco-Friendly Synthesis, Characterization, and Pharmacological Assessment of Silver Nanoparticles obtained from Indigofera astragalina: A Combined Approach to Antimicrobial and Antioxidant Therapeutics

Nanotechnology and phytomedicine offer innovative methods for developing novel drugs. The ecologically friendly production of nanoparticles of silver (AgNPs) with substances derived from plants provides a biocompatible and environmentally acceptable substitute for traditional techniques by utilizing the inherent phytochemical bioactivity. Indigofera astragalina (IA), which is high in flavonoids and phenolic, was employed as a reductant and stabilizer. Silver nanoparticles produced with IA leaf extract (i.e. IA-AgNPs) were examined utilizing ultraviolet-visible light SEM/TEM, XRD, FTIR, and DLS. The results showed that the obtained IA-AgNPs were spherical, crystalline nanoparticles having an average size of 8.2 nm and excellent stability i.e. a zeta potential of -53.06 mV. The agar well diffusion method was used to assess its antimicrobial efficacy against species of Gram-positive (S. aureus, and B. cereus), Gram-negative (E. coli, and K. pneumoniae) and Candida albicans pathogens, followed by their MIC, MBC, and IC₅₀ analysis. The MIC values of IA-AgNPs were 8–16 times lower than those of the crude extract, showing a marked higher level of dose-dependent inhibition. Significant efficacy was observed against Candida albicans (MIC: 0.78 μg/mL; IC₅₀: 0.6 μg/mL). IA-AgNPs demonstrated superior radical quenching ability, as evidenced by their antioxidant activity measured through superoxide scavenging assays (86.9%). The significant bio enhancement highlights a combined effect between the surface-bound phytochemicals and silver core, supporting the ethno pharmacological application of IA and establishing IA-AgNPs as a prospective multifunctional biotherapeutics that combat infections and scavenge free radicals.