Phytotoxicity and pro-oxidant effects of green-synthesized silver nanoparticles from Copaifera langsdorffii leaf and leaf litter

The environmental release and increasing use of silver nanoparticles (AgNPs) have raised concerns regarding their potential adverse effects on non-target organisms. The aim of this study was to investigate the potential phytotoxic and pro-oxidant effects of AgNPs green-synthesized products using aqueous extracts of Copaifera langsdorffii leaf (ClLENPs) or leaf litter (ClLLNPs). Phytochemical analysis displayed a phenolic profile rich in galloylquinic acid derivatives. The synthesized ClLLNPs exhibited surface plasmon resonance bands between 400 and 460 nm, an average hydrodynamic diameter of 18.59 ± 0.57 nm, a polydispersity index of 0.43 ± 0.02, and a zeta potential of −35.31 ± 1.92 mV. ClLE and ClLL presented 2,161.15 ± 94.89 and 822.63 ± 31.51 mg GAE/g DW of total polyphenols and 1,579.87 ± 78.7 and 856.53 ± 12.59 mg RE/g DW of flavonoids, respectively. AgNPs synthesized using ClLE or ClLL exhibited polyphenol and flavonoid contents that did not differ markedly between each other. In pre-emergence assays, ClLL markedly reduced Lactuca sativa germination, whereas ClLLNPs produced moderate inhibition. Both ClLL and ClLLNPs significantly blocked Bidens pilosa germination, presenting inhibition comparable to the commercial herbicide Glyphosate®. ClLLNPs also diminished Triticum aestivum coleoptile growth similar to herbicide treatment. In addition, both ClLL and ClLLNPs promoted oxidative degradation of bovine serum albumin, indicating pro-oxidant activity potentially associated with reactive oxygen species formation. These results demonstrate that AgNPs synthesized using C. langsdorffii leaf or leaf litter might exert biologically relevant phytotoxic and pro-oxidant effects and indicate the importance of determining ecological and toxicological consequences of green-synthesized nanomaterials prior to their environmental application.