Biogenic Chromium (III) Nanoparticles From <scp> <i>Adiantum capillus‐veneris</i> </scp> Exhibit Potent Antioxidant and Antidiabetic Effects

ABSTRACT Chromium is an essential trace element that exerts antidiabetic effects by enhancing insulin sensitivity and upregulating key proteins and genes involved in glucose uptake and metabolism. The antidiabetic potential of chromium nanoparticles (CrNPs) and Adiantum capillus‐veneris has been studied separately; however, the conversion of chromium into biogenic CrNPs using the plant extract and the evaluation of their effects on carbohydrate‐hydrolyzing enzymes remain unexplored. In this study, CrNPs were synthesized using A. capillus‐veneris extract, characterized through various instrumental techniques and evaluated for their antioxidant and antidiabetic potential in vitro. The optimal synthesis was achieved at a 4:9 (v/v) ratio of plant extract to chromium salt. The synthesized CrNPs were crystalline, irregular to round in shape, with sizes ranging from 58 to 90 nm, thermally stable up to 280°C, and exhibited a strong absorbance peak in the UV–Vis range at 420 nm. EDX analysis confirmed the presence of chromium at ~0.6 keV. The resulting CrNPs showed excellent antioxidant (DPPH, IC 50 = 100 μg/mL; ABTS, IC 50 = 125 μg/mL) and notable inhibition of carbohydrate‐hydrolyzing enzymes; α‐amylase (91.3% inhibition at 1000 μg/mL, IC₅₀ = 127 μg/mL) and α‐glucosidase (86.4% inhibition at 1000 μg/mL, IC₅₀ = 140 μg/mL). CrNPs exhibited stronger biological potentials and outperformed both the aqueous and methanolic extracts of A. capillus‐veneris plant, as well as chromium chloride hexahydrate in the antioxidant and antidiabetic assays. In conclusion, these activities are likely due to enhanced bioavailability and polyphenol–enzyme interactions, which significantly improved the activity of chromium chloride hexahydrate upon its conversion into CrNPs. Further validation in experimental diabetic models is warranted.