EVALUATION OF IN VITRO ANTIOXIDANT PROPERTIES OF CALLUS CULTURES OF AN ENDANGERED MEDICINAL TREE SPECIES, HILDEGARDIA POPULIFOLIA (ROXB.) SCHOTT & ENDL.

Protocol for efficient callogenesis in Hildegardia populifolia has been developed by using leaf, node, internode and petiole explants. Preliminary phytochemical analysis and quantitative estimation of flavonoids, phenols and tannins were made along with the evaluation of antioxidant properties by DPPH^• and ABTS^•+ assays in in vitro callus cultures of the same species. It is an indigenous endangered multipurpose medium sized tree being used for traditional medical practices in Tamil Nadu and Andra Pradesh. Among the explants, the efficient callogenesis was accelerated within 10-19 days in leaf explant on Murashige and Skoog (MS) medium supplemented with 2, 4-D alone at 2 mg/L. Effective calli were produced from node (BAP and IAA at 2 mg/L and 0.4 mg/L respectively in MS medium), internode (2,4-D at 2 mg/L in MS medium) and petiole (2,4-D at 2 mg/L in MS medium) explants. The phytochemical study revealed that phenolics and tannin content were higher in 60 days old leaf callus cultures. Flavonoid content was more in 60 days old internode derived callus culture. Evaluation of antioxidant property established that DPPH^• radical scavenging activity was relatively higher in leaf derived callus (86.24 mg/g) and ABTS^•+ activity was higher in internode derived callus (3077.98 µmol TE/g extract). This study had shown that plant tissue culture offers itself as a highly efficient method for mass propagation and conservation of H. populifolia and also helps to identify the unique in vitro culture with natural antioxidant potential to get health care benefits.