Green synthesis of silver nanoparticles using aqueous extract of ‎Aloysia citrodora leaves and investigation of antioxidant, anti-‎amyloid and anti-cancer properties

Aloysia citrodora is very important in Iranian traditional medicine. The aim of this study was to produce silver nanoparticles with aqueous extract of A. citrodora and investigate its antioxidant and inhibitory effects on the amyloid nanofibers from BSA as model protein. For synthesis of silver nanoparticles, aqueous A. citrodora extract was prepared and one mM silver nitrate was added to solution. To confirm the presence and determine the size of silver nanoparticles, UV-Vis spectroscopy and TEM were used. The antioxidant effect of the extract was evaluated by DPPH and the production of amyloid fibers was measured by Congored absorption method. The toxicity effect of nanoparticles on neuroblasts was investigated by MTT method and the inhibitory properties of the extract on amyloid production were investigated by TEM. Caryophyllene (7.66%), phytol (7.47%) and limonene (2.68%) were the most abundant compounds. TEM also confirmed spherical crystalline nanoparticles with a size between 30–70 nm. By increasing the concentration of the extract, the antioxidant properties of nanoparticles increased, so that 97.35% of DPPH free radicals were inhibited at a concentration of 1 mg/ml. The highest inhibition of amyloid fibrils production was observed at concentration of 2 mg/ml by 96%, and the highest level of cytotoxicity at a concentration of 2 and with an IC50 of 2.25 mg/ml. The results showed that nanoparticles from A. citrodora leaves with anti–amyloid, antioxidant and anticancer properties can be considered as a new bio–nanomaterial in reducing Alzheimer's and cancer complications.