Antioxidant activity of extract from a brown alga, Sargassum boveanum

Water and ethanol extracts (WE and EE) from the dried sample of brown alga (Sargassum boveanum) were prepared and examined for its phenolic compounds. Amount of total phenolic compounds in WEwas about 17 ± 0.492 mg catechin equivalent (CE)/g of dry sample, using Folin-Ciocalteu method. The antioxidant activity (AOA) of WE was high at about 90% inhibition of peroxidation of linoleic acid with 7mg dry sample/ml solvent. The IC50 of the WE sample and catechin which was used as the positive control with the hemoglobin catalyzed linoleic acid peroxidation method, were (mg/ml): 3.82 and 0.0713, respectively. The IC50 of the WE sample in terms of CE was 18.76 mg CE/g dry sample.The WE sample exhibited noticeable scavenging effects in DPPH free radical scavenging assay. The radical scavenging activity (RSA) was about 94% at 3 mg dry sample/ml solvent. The phenolic constituent appears to be responsible at least in part, for the observed AOA of the algal extract. The results suggest that this alga could be a potential source of natural antioxidant