Biomass and Secondary Metabolites Enhancement in Bhringraj (Eclipta alba L.) Callus Culture Through Silver Nanoparticles Elicitation.

Silver nanoparticles (AgNPs) have surfaced as a potential agent for the augmented biosynthesis of secondary metabolites in vitro plant cultures. This research examines the impact of different concentrations of silver nanoparticles (2.0, 4.0, 6.0, 8.0, 10.0 and 12.0 mg/L) in combination with 6-Benzylaminopurine (BAP) (1.0 mg/L) and other supplementary compounds such as ascorbic acid (0.050 g/L), adenine sulfate (0.025 g/L), arginine (0.025 g/L) and citric acid (0.025 g/L) on callus growth and secondary metabolites synthesis. The findings demonstrated that different concentrations of AgNPs had a notable impact on callus proliferation and led to a considerable enhancement in callus biomass. The most significant accumulation of fresh (19.170 g/L) and dry (1.842 g/L) callus biomass was recorded in the in vitro cultures supplemented with 8 mg/L AgNPs. The phytochemical analysis of the callus cultures revealed a notable increase in the production of phenolics (35.40 mg/g of DW), flavonoids (15.0 mg/g of DW), total protein content (18.76 mg/g of DW), total antioxidant activity (73.33 µg/mg of DW) and total reducing power (93.36 µg/mg of DW) in the cultures established on MS media supplemented with 8 mg/L AgNPs. Additionally, the antioxidant activity reached an impressive 97.3% at a concentration of 10 mg/L AgNPs. It can be inferred that the AgNPs serve a significant role in augmenting bioactive antioxidants within the callus cultures of E. alba, a plant of considerable medicinal value and conservation concern. This protocol can be expanded for large-scale synthesis of plant biomass and therapeutic metabolites in E. alba.