Green synthesis of silver nanoparticles mediated by Solanum nigrum leaf extract and their antifungal activity against pine pathogens

Extracts from medicinal and aromatic plants have great benefits in controlling plant diseases. In this regard, the leaf aqueous extract (LAE) from the wild plant Solanum nigrum (L.) was used for the green synthesis of silver nanoparticles (AgNPs). The phytochemicals in the LAE were characterized by HPLC and FTIR analysis. The synthesized AgNPs were characterized using Transmission Electron Microscope (TEM), Energy Dispersive X-Ray (EDX), zeta potential, and FTIR Analysis. By HPLC analysis, the major compounds in the LAE were chlorogenic acid, gallic acid, syringic acid, and caffeic acid. The TEM analysis revealed that the average particle size ranged from 3.45 to 8.79 nm. The LAE and the synthesized AgNPs were evaluated for their antifungal activity against molecularly identified fungi Fusarium circinatum, Phoma sp., and Pythium tardicrescens, isolated from the diseased branches of the Pinus halepensis (Mill.) tree. At the LAE concentration of 1000 µg/mL, the fungal inhibition was reached 43.33%, 72.22%, and 37.40% against the growth of P. tardicrescens, F. circinatum, and Phoma spp., respectively. The synthesized AgNPs at 75 µg/mL showed fungal inhibition values of 58.14%, 56.66%, and 40.37% against P. tardicrescens, F. circinatum, and Phoma spp., respectively. Thus, the current study suggested producing stable, nontoxic, and eco-friendly Ag nanoparticles using the aqueous extract of S. nigrum leaves.