In Vitro Antioxidant Profile of Methanol Leaf Extract of Securidaca longepedunculata

The serious problem associated with the use of plants parts for medicinal purposes is the paucity of information on the phytochemistry, pharmacology, antioxidant contents and toxicity of most of the medicinal plants.The aim of this study is to evaluate the antioxidant property of the leaves of S. longepedunculata with a view to elucidating its antioxidant potential.The potent secondary metabolites in the leaves ofSecuridacalongepedunculata , were extracted and the antioxidant potential, evaluated using in vitro methods.Results showed that the methanol extract scavenged 1, 1-diphenyl-2-picrylhydrazyl radical (DPPH .) in a concentration dependent manner with a correlation coefficient (R 2 ) of 0.976, indicating antioxidant activity with effective concentration that inhibits 50 percent of the radicals (EC 50 ) of 90.02±0.2µg/mlcompared to ascorbic acid standard(EC 50 of 98.01±0.2µg/ml).Superoxide radical scavenging activity was concentration dependent with an EC 50 of 350.11±0.42µg/mlcompared with ascorbic acid standard with EC 50 of 812.97±0.97µg/ml.The extract, also showed hydroxyl radical scavenging activity with an EC 50 of 83.74±0.02µg/mlcompared to αtocopherol standard with EC 50 of 54.16±0.01µg/ml.There was an inverse correlation between the percentage inhibition and concentration with R 2 of -0.958.The methanol extract, also scavenged nitric oxide radical in a concentration dependent manner with 500 µg/ml being more effective than 500 µg/ml of ascorbic acid standard.Comparison of the anti-radical power (ARP) of DPPH .(0.011), superoxide radical (0.003) and hydroxyl radical (0.012) of the extract revealed that the ARP of hydroxyl radical was most efficacious.The antioxidant vitamin contents of the extract showed that vitamin C was significantly high (p< 0.05), (4.62±0.14mg/100g) when compared to vitamin A (0.902±0.05 µg/g) and vitamin E (1.474±0.01mg/100g).This result suggests a moderate antioxidant activity which is healthy for a biological system to reduce the deleterious effects associated with excessive free radical generation.