Centella asiatica L. callus mediated biosynthesis of silver nanoparticles, optimization using central composite design, and study on their antioxidant activity

This study proposes the tenacious vitality for biomass production and eco-friendly, cost-effective, renewable silver nanoparticles (AgNPs) biosynthesis approach for beneficial utilization. For the first time, halogen dried callus biomass obtained from petioles of Centella asiatica L. (CA) was utilized for biosynthesis of AgNPs through process optimization using face-centered central composite design. Non-embryogenic, whitish-yellow callus propagated on B5 medium augmented with 2,4-D (1.00 mu M) and TDZ (0.50 mu M) was utilized for the synthesis of AgNPs. Qualitative and quantitative phytochemical estimation indicated the presence of active ingredients such as total phenolic, flavonoids, tannins, saponins, and terpenoids in aqueous callus extract. The characterization techniques reinforced each other and affirmed the ability of CA callus extract to fabricate AgNPs with an average size of 32.9 nm and maximum absorbance at 443 nm. Also, the presence of elemental Ag, spherical shape, and crystalline nature was confirmed by SEM and EDX, TEM, and XRD analysis respectively. FTIR and phytochemical screening confirmed the presence of bioactive functional groups in CA callus AgNPs. Both callus extract and AgNPs exhibited potential antioxidant activity in a dose-dependent manner. Key message The callus culture obtained from agricultural residue of Centella asiatica served as a novel source for statistical optimization and biosynthesis of spherical and crystalline silver nanoparticles possessing potent antioxidative property.