EVALUATION OF ANTIOXIDANT CAPACITY OF METHANOL EXTRACT AND ITS SOLVENT FRACTIONS OBTAINED FROM FOUR MOROCCAN MACRO ALGAE SPECIES

Abstract

In vitro antioxidant activities of methanolic extract and its solvent fraction (petroleum ether (PE), ethyl acetate (EA), dichloromethane (DCM), butanol (BuOH) and aqueous) were obtained from four Moroccan macroalgae species: Ulva rigida, Enteromorpha intestinalis, Fucus spiralis and Bifurcaria bifurcata using DPPH scavenging activity, metal chelating activity and total phenol content. Brown algae, Bifucaria bifurcata and Fucus spiralis contained higher amounts of polyphenols than green algae, Enteromorpha intestinalis and Ulva rigida . DCM fraction of Fucus spiralis and EA fraction of Bifucaria bifurcate showed higher phenolic content (29,79 and 24,44 mg gallic acid equivalent/g DW extract respectively) when compared to other solvent fraction and total methanol extract. DPPH radical scavenging activity of algae species extract tested showed lower activity than that of a standard compounds: ascorbic acid (EC 50 = 0,11 mg /ml) and α tocopherol (EC 50 = 0,215 mg /ml). Aqueous fraction of Enteromorpha intestinalis exhibited the most effective scavenging ability on DPPH radical (68,70%) than other fraction at the concentration of 3 mg/ml followed by aqueous and EA fraction of Fucus spiralis (49,50% and 50% respectively). The antioxidant activity of seaweed extracts increased in concentration-in a dependent manner. In accordance with DPPH results, potent chelation abilities were again detected in methanolic extract and its solvent fraction. All solvent and aqueous fraction of Ulva rigida and Fucus spiralis exhibited equivalent chelating effects as compared to EDTA-Na2 standard compound (IC50 was lower than 0,05mg/ml). The other fractions of Bifucaria bifurcata and Enteromorpha intestinalis showed less potent chelating effect as compared to other seaweeds (IC50 was high than 0,4mg/ml). However, there was no direct relationship between antioxidant activity and the phenolic content, suggesting that polyphenol play a minor role in the metal chelating ability and other compounds such as polysaccharides, protein, organic acid which can contribute to the overall antioxidant activities.