Evaluation of antioxidant and radical-scavenging activities of certain radioprotective plant extracts

The extract of Adhatoda vasica, Amaranthus paniculatus, Brassica compestris, Mentha piperita and Spirulina fusiformis has radioprotective effects in animal model systems. In the present investigation, the extracts of A. vasica, A. paniculatus, B. compestris, M. piperita and S. fusiformis were further evaluated for their antioxidant (GSH&LPO) and radical-scavenging activities (DPPH and ABTS+ assays). All these plant extracts showed antioxidant activity, as measured by estimating reduced glutathione and lipid peroxidation in liver, and showed radical-scavenging activity in both DPPH and ABTS+ assays. The extracts of M. piperita, A. vasica and B. compestris showed very strong radical-scavenging activity in both the assays. However, extracts of A. paniculatus and S. fusiformis showed moderate radical-scavenging activity. The IC50 values of these plant extracts were: M. piperita – 273 μg/ml, A. vasica – 337 μg/ml, B. compestris – 398 μg/ml, A. paniculatus – 548 μg/ml and S. fusiformis – 620 μg/ml, respectively. The differential radioprotective and antioxidant activity of these plant extracts observed may be assigned to different chemical constituents present in the different plant extracts. The result of the present investigation indicates that the antioxidant mechanism of radioprotection and free-radical scavenging appear to be likely mechanisms of radiation protection by these plant extracts.