Green synthesis of silver nanoparticles using food supplement from Avena sativa L., and their antioxidant, antiglycation, and anti-aging activities: In vitro and in silico studies

Food supplement of Avena sativa L. dry extract (AsDE) is produced with green leaves of wild oats and it is commonly used in patients with cognitive disorders and muscle deficits. These symptoms and pathologies can be promoted and/or aggravated by oxidative stress and protein glycation. In order to prevent or treat these disorders, new formulations that could enhance and benefit AsDE have been developed and the formation of metallic nanoparticles by green synthesis has shown to be an alternative. Thus, this study aimed to prepare silver nanoparticles (AgNPs) by green synthesis using AsDE and characterize these AgNPs. Besides, it aimed to evaluate in vitro antioxidant and antiglycation activities of AsDE and AgNPS, and analyze in vitro and in silico inhibitory action on aging enzymes (collagenase, elastase, and tyrosinase). UV–visible spectroscopy, Zeta potential and scanning transmission electron microscopy were used to characterize AgNPs. Antioxidant activity was determined by DPPH free radical scavenging, ferric ion reducing power (FRAP), lipid peroxidation inhibition, ABTS radical scavenging, and oxygen radical absorption capacity (ORAC). Molecular docking analyses were performed to evaluate interactions between the major compounds of AsDE and aging enzymes or DNA. Antioxidant tests demonstrated antioxidant activity of 19.67 % for AsDE and 42.98 % for AgNPs in DPPH test; and 115.67 µM Trolox Equivalent (TE)/g for AsDE and 554.33 µM TE/g for AgNPs in FRAP test. In addition, AsDE and AgNPs inhibited 25.40 % and 11.33 % of lipid peroxidation, respectively, and presented 255.22 µM TE/g for AsDE and 317.44 µM TE/g for AgNPs in ABTS test. AsDE and AgNPs exhibited antioxidant potential observed in ORAC assay. In addition, AsDE presented inhibitory action on collagenase, elastase and tyrosinase activities (78.23 %, 68.14 % and 62.27 % inhibition, respectively). Antiglycation tests demonstrated that bovine serum albumin exposed to ribose and treated with AsDE at 0.5 mg/mL exhibited the highest percentage of free amino groups (45.21 %), while samples treated with AgNPs showed 35.41 % free amino groups. On the other hand, AgNPs exhibited the highest percentage of inhibition of advanced glycation end-products formation (85.75 %), which did not differ from aminoguanidine, a known antiglycation agent. Besides, relative electrophoretic mobility assay demonstrated that samples treated with AsDE at 0.1 mg/mL or AgNPs showed antiglycation activity comparable to aminoguanidine. The in silico assays showed interactions between the major compounds of AsDE and aging enzymes or DNA. Therefore, results represent an important indicator for the development and discovery of new nanostructured pharmaceutical and cosmetic formulations using plants and their bioactive compounds.