Biosynthesis of precious metabolites in callus cultures of Eclipta alba

Eclipta alba (False daisy) is an important medicinal plant with well-known antihepatotoxic activity. However, no previous in vitro studies are available for its callus culture for increased production of antioxidant secondary metabolites. Herein, we maintained a competent protocol for callus culture of E. alba using stem and leaf explants grown on MS medium containing various concentrations of thidiazuron, 6-benzylaminopurine (BAP) either alone or in association with -naphthalene acetic acid (NAA). Among all the applied plant growth regulators, BAP along with NAA resulted in maximal dry biomass of 18.0 and 13.8g/l for stem and leaf explants, respectively. Furthermore, the highest production of phenolics (375.7mg/l for stem-associated callus and 298mg/l for leaf-associated callus) and flavonoids (62.0 and 52.3mg/l for stem- and leaf-associated callus, respectively) were found to be present in optimized callus culture. Antioxidant activity was also elucidated for both stem and leaf derived calli. The highest antioxidant activities (93.5%) were witnessed for stem and leaf associated calli at set concentrations of 3.0mg/l BAP+1.0mg/l NAA and 4.0mg/l BAP, respectively. High-performance liquid chromatography analyses revealed optimum accumulation of coumarin (1.98mg/gDW) and wedelolactone (49.63mg/gDW) in leaf associated callus and desmethylwedelolactone (69.96mg/gDW), -amyrin (0.8179mg/gDW) and eclalbatin (0.3202mg/gDW) in stem associated callus at optimized concentration.