Catalytic and biocidal activity of silver and gold nanoparticles obtained by green synthesis using aqueous extracts of glossy privet (Ligustrum lucidum) dry fruits

Metallic nanoparticles (NPs) have gained interest due to their practical applications in various areas. The synthesis of NPs from biomass proposes a simple, economical and environmentally friendly alternative. In this work, gold NPs (AuNPs) and silver NPs (AgNPs) were synthesized from aqueous extracts of dried Ligustrum lucidum fruits. The biomolecules of the extract, in addition to acting as a reducing agent, are absorbed on the surface of the NPs giving excellent colloidal stability, increasing their catalytic capacity reflected in their recyclability. The TON and TOF values obtained for the reduction reaction of 4-nitrophenol in the presence of NaBH₄, are 1.4 10⁵ and 500 s⁻¹ respectively. Minimum inhibitory concentrations (MICs) were established for AgNPs using pathogens from certified collections (E. coli MIC = 25 µg/mL; S. aureus MIC = 100 µg/mL). Fractional inhibitory concentration indices (FICIs) in the presence of gentamicin showed synergistic effects (FICI = 0.5). The results demonstrate that the aqueous extract of L. lucidum allows the synthesis of AuNPs and AgNPs, which have attractive catalytic and antimicrobial activities, in a simple and environmentally friendly way.