Production of Boeravinone-B, total phenolic, flavonoid content and antioxidant activity from callus cultures of Punarnava (Boerhavia diffusa L.)

Boerhavia diffusa L. (Punarnava) is a medicinal herb, rich in diversified plant secondary metabolites used in curing various health ailments. Boeravinone-B is one of the important phytochemicals reported in Punarnava, possessing various pharmacological activities. It belongs to the family of rotenoids, belonging to the isoflavone group. Production of Boeravinone-B from the Punarnava through conventional propagation is comparatively very low, and alternative interventions are of utmost importance to meet the growing demand. In view of this, the present study aims to develop biotechnological approaches like cell/tissue culture as a substitute strategy for the accumulation of biomass and Boeravinone-B biosynthesis. Callus was established from leaf explants of Boerhavia diffusa L. when cultured on MS semi solid medium fortified with varied concentrations and combinations of auxins and cytokinins. The callus induced on Murashige and Skoog medium (MS medium) supplemented with 5.0 ppm 2,4-Dichlorophenoxyacetic acid (2,4-D) favored the highest production of Boeravinone-B analyzed through High-performance Liquid chromatography (HPLC) and it was found to be 673.95 mu g g-1 Dry weight (DW). The total phenolic and flavonoid content were determined for the callus extracts and the results showed that callus induced on 5.0 ppm 2,4-D medium showed the highest phenolic and flavonoid content, which was 63.48 mg g-1 Gallic acid equivalent (GAE) Dry weight (DW), and 30.22 mg g-1 Quercetin equivalent (QE) DW. Similarly, antioxidant activities (radical scavenging, metal chelating, and reducing power) were performed, and it was found that callus induced on 5.0 ppm 2,4-D showed the highest anti-oxidant potential. Radical scavenging activity was found to be 91.1%, and 74% of metal chelating activity was recorded, and a similar trend was observed with respect to reducing power as well. The results of the present study lay foundation for optimization and subsequent large-scale production of Boeravinone-B from callus/cell suspension cultures.