Evaluation of Antioxidant Activity of Five Medicinal Plants in Sri Lanka

This study investigated on the antioxidant properties of five medicinal plants used in Sri Lanka, namely Solanum nigrum, Amaranthus spinosus, Elephantopuss caber, Amorphophallus campanulatus and Canna indica. The cold methanol plant extracts were screened for the antioxidant activity evaluating their 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical in scavenging ability. The total ascorbic acid content of the extracts was also evaluated. The IC 50 values of the extracts revealed that Solanum nigrum had the best DPPH scavenging activity with a value of 37.63 ± 0.11µg/ml and was better than that of the standard ascorbic acid. Amorphophallus campanulatus extract gave the highest ascorbic acid content of 143.03 ± 1.97 mg per 100 g of the extract. All five plants extract showed DPPH scavenging activity in the order of Solanum nigrum > Elephantopus scaber > Amorphophallus campanulatus > Canna indica. The plant extracts did not show a direct correlation between the ascorbic acid content to the DPPH scavenging activity. These experimental results reveals that these extracts can be utilized in future as therapeutic agent against free radical induced oxidative stress.