Green Propolis Extract-Mediated Synthesis of Biogenic Silver Nanoparticles: In Vitro Antileishmanial and Antibacterial Activities, Cytotoxicity and Ex Vivo Irritation Testing.

This study describes the green synthesis, characterization, and biological evaluation of silver nanoparticles (AgNPs) obtained from green propolis (AgNPs-PRO). Before nanoparticles synthesis, a hydroethanolic green propolis extract (GPE) was obtained through ultrasound-assisted extraction and characterized by high-performance liquid chromatography, revealing the artepilin C as the most abundant phenolic compound in its composition, followed by 4,5-dicaffeoylquinic acid and drupanin. The analysis of synthesized AgNPs by UV-Vis spectroscopy showed a characteristic absorption band at 430 nm. Dynamic light scattering analysis revealed mean hydrodynamic particle sizes ranging from 88 to 115 nm, with a polydispersity index between 0.229 ± 0.006 and 0.365 ± 0.054. Fourier-transform infrared spectroscopy confirmed that functional groups present in GPE contribute to the reduction and stabilization of AgNPs. Differential scanning calorimetry and transmission electron microscopy confirmed that AgNPs were obtained. GPE showed leishmanicidal activity against promastigote forms of Leishmania amazonensis, with a half-maximal inhibitory concentration (IC50) of 11.87 µg/mL and a selectivity index (SI) of 12.52. Antibacterial activity of the AgNPs, assessed via the disk diffusion method, revealed inhibition zones against Escherichia coli (Gram-negative), Staphylococcus aureus (Gram-positive), and Candida albicans strains. The HET-CAM test indicated no signs of irritation, suggesting the biocompatibility of the developed AgNPs.