ANTIOXIDANT ACTIVITY IN CALLUS CULTURES AND IN VITRO REGENERATED PLANTS OF ARTEMISIA NILAGIRICA (CLARKE) PAMP.- AN IMPORTANT MEDICINAL PLANT SPECIES

ABSTRACT: Antioxidant  potential  of  in  vitro  callus  and  regenerated  plants  of  Artemisia nilagirica  was  investigated  using  several  biochemical  assay  techniques  for scavenging of 1,1-diphenyl -2-picryl hydrazyl (DPPH), nitric oxide, superoxide and  hydroxyl  radicals  as  well  as  lipid  peroxidation.  The  internodal  explants from  A.  nilagirica  were  cultured  on  Murashige  and  Skoog’s  (1962)  basal medium (MS) supplemented with various concentrations and combinations of plant  growth  regulators.  A  synergistic  coupling  of  0.5  mg/L  2,4- dichlorophenoxyacetic  acid  (2,4-D)  with  1.0  mg/L  Kinetin  (Kin)  yielded maximum  callogenic  response.  Shoot  organogenesis  in  callus  cultures  was most favoured in MS containing 2.0 mg/L 6-benzylaminopurine (BAP) and 0.5 mg/L indole-3-acetic acid (IAA). In vitro regenerated plantlets, emerged from culture medium, were acclimatized and the survival rate of ex vitro plants after soil transplantation  was 80-83% with  no apparent  phenotypic variations. The antioxidant  potential  of  natural  (in  vivo)  plants,  callus  tissues  and  in  vitro regenerated plants before and after field transplantation (ex vitro) plants were compared. DPPH scavenging activity was the highest in aqueous extracts of 10 week-old ex vitro plants than  other  sources.  Superoxide  anion  and  nitric  oxide  radical  scavenging  activity  was  the  highest  in ethanolic  extracts  of  10 week-old  ex  vitro  plants  where  as  the  hydroxyl  radical  was  the  maximum  in  6 week-old in vivo plants. Lipid peroxidation was neither observed in calli nor in regenerated plants of A. nilagirica.