Multifaceted biological activities of <i>Aspalathus linearis</i> -based silver nanoparticles: from oxidative stress modulation to regeneration

This study reports Rooibos-mediated silver nanoparticles (R-AgNPs) using the aqueous extract of <i>Aspalathus linearis</i> (Rooibos) and evaluates their multifunctional biological activities. The synthesis of R-AgNPs was indicated by a colour change from yellow to brown and a characteristic absorption peak at 432 nm. R-AgNPs were predominantly spherical, EDS confirmed the presence of silver, while XRD revealed a crystalline structure with an average particle size of 13.94 nm. The cytotoxic potential of R-AgNPs was assessed in SK-MEL-30 and L929 cells. Dose-dependent decreases in cell viability were observed, with respective IC₅₀ values of 17.32µg/mL and 30.07 µg/mL. Wound healing assays revealed that a dose of 6.25 µg/mL significantly increased fibroblast migration, resulting a 60.5-fold increase in wound closure at 24 hours, compared to a 22.6-fold in the control group. At 12 hours, R-AgNPs had accelerated cell migration by around fourfold. R-AgNPs increased TAS and reduced TOS and OSI in SK-MEL-30 cells, while maintaining near-normal oxidative balance in L929 cells. R-AgNPs exhibited concentration-dependent DPPH radical scavenging activity (25.87-65.91%) and strong α-glucosidase inhibition (31.86-100%), indicating their potential as antioxidants and antidiabetics. In conclusion, R-AgNPs exhibit selective cytotoxicity, antioxidant capacity, wound-healing promotion, and antidiabetic activity, highlighting their potential as safe, multifunctional nanotherapeutics for biomedical use.