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 E. spinosum and S. crassifolium that are potential natural sources of antioxidants. The cleaned E. spinosum (637.53 g) and S. crassifolium (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 E. spinosum had low free radical scavenging activities, while all three (crude methanol, n- hexane and DCM) extracts of S. crassifolium exhibited significant antioxidant activities (50.93%, 61.07% and 57.89% respectively). Since the n- hexane extract of S. crassifolium 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 E. spinosum, it contained several phytochemicals whereas only terpenes were present in S. crassifolium.