Evaluation of Antioxidant Activities of Some Abundant Marine Macroalgae, Egypt

Abstract

This study investigated the antioxidant scavenging activity of nine marine macroalgae extracts collected from different Egyptian coasts. The extracts were tested using the DPPH assay to exhibit various antioxidant activities. All extracts showed lower DPPH free radical scavenging compared to ascorbic acid. Antioxidant effects increased with extract concentration, with brown algae exhibiting the highest activity among green and red algae. Specifically, the brown alga Polycladia myrica extract was most effective against DPPH free radicals, while the green alga Ulva fasciata demonstrated the lowest scavenging effect. At a concentration of 1000ug/ml, the most effective species against DPPH free radicals were brown macroalgae (Polycladia myrica > Turbinaria turbinata > Hormophysa cuneiformis), followed by red macroalgae (Jania rubens > Hypnea cornuta > Galaxura rugosa), whereas the green macroalgae showed the lowest scavenging effect (Caulerpa racemosa > Halimeda tuna > Ulva fasciata). The IC50 values indicated that Ulva fasciata, Halimeda tuna, and Caulerpa racemosa had the highest antioxidant activity, then red algae Galaxura rugosa> Hypnea cornuta> Jania rubens while brown algae Hormophysa cuneiformis, Turbinaria turbinata, and Polycladia myrica recorded the lowest values. Overall, the studied macroalgae species demonstrated significant antioxidant potential due to bioactive compounds like polyphenols, saponins, and tannins. Caulerpa racemosa exhibited the highest polyphenol concentration, while Galaxura rugosa had the lowest. Ulva fasciata, Hormophysa cuneiformis and Polycladia myrica showed the highest total saponins content, while Hypnea cornuta registered the highest total tannins content. These findings suggest that macroalgae could serve as dietary alternatives due to their strong antioxidant capabilities.