Evaluation of antioxidant activity of <i>Eucheuma spinosum</i> and <i>Sargassum crassifolium</i> through 1, 1 - DIPHENYL - 2-PICRYLHYDRAZYL (DPPH) method and phytochemical screening

Abstract

The study aims to evaluate the antioxidant activity of <i>E. spinosum</i> and <i>S. crassifolium</i> that are potential natural sources of antioxidants. The cleaned <i>E. spinosum</i> (637.53 g) and <i>S. crassifolium</i> (288.46 g) samples were macerated for 48 hours using 80% methanol. The crude methanol, n — hexane and DCM extracts of these two seaweed samples were assayed for their free radical scavenging activities using the DPPH Free Radical Scavenging Method. Ascorbic acid (250 mg/L) and DPPH (20 mg/L) solutions were used as positive and negative controls respectively. The results showed that all three extracts of <i>E. spinosum</i> had low free radical scavenging activities, while all three (crude methanol, n- hexane and DCM) extracts of <i>S. crassifolium</i> exhibited significant antioxidant activities (50.93%, 61.07% and 57.89% respectively). Since the n- hexane extract of <i>S. crassifolium</i> showed the highest antioxidant activity from the samples, its half maximal effective concentration was measured and found to be 79.69 mg/L and was higher than Ascorbic Acid (12.42 mg/L). In contrast to the very low free radical scavenging activity of <i>E. spinosum</i>, it contained several phytochemicals whereas only terpenes were present in <i>S. crassifolium</i>.