Effect of chemical and biological elicitors on antioxidant potential of Ocimum sanctum

Medicinal plants are a known source of antioxidants and are used for the prevention and treatment of diseases. Exogenous application of elicitors can be used to improve the antioxidant profiles of medicinal plants enhancing their therapeutic potential. Present study aimed to study the effect of elicitors such as proline, salicylic acid and a plant growth promoting rhizobacteria-Azospirillum on antioxidant potential of medicinal plant -Ocimum sanctum. Semi-quantitative assay-thin layer chromatography (TLC), and quantitative assays such as DPPH (2,2Diphenyl-1-picrylhydrazyl) for free radical scavenging activity, total phenolic content and antioxidant responsive enzymes SOD (superoxide dismutase) and CAT (catalase) activities were used for the assessment based on standard protocols. Growth changes like number of leaves, root length, shoot length, total plant height, fresh weight and dry weight observed in response to the treatments given. Exogenous application of proline, salicylic acid and Azospirillum enhanced growth and overall antioxidant content of treated plants. Proline showed higher elicitation with high phenolic content (47.66 GAE/gm. wt.) and number of distinct bands (18) in TLC. The DPPH assay also showed higher free radical scavenging potential (70.32% reduction) of proline treated plants. Enhanced activity of antioxidative enzymes CAT and SOD was also observed in all the treated plants. The study confirms the effectivity of using these elicitors for enhancing antioxidant potential of medicinal plants.