Abstract:Comparison of antioxidant activities of the different extracts from three seaweeds in Fujian Quanzhou Bay.Research for the relationship between antioxidant activity of the extracts and total phenolics，total flavonoids and total sugar.Selecting the extracts and seaweeds with high antioxidant activity.The antioxidant activities of the extracts were determined with hydroxyl radical scavenging test、superoxide anion radical scavenging test and DPPH（1，1-Diphenyl-2-picrylhydrazyl radical 2，2-Diphenyl-1-（2，4，6-trinitrophenyl）hydrazyl）free radical scavenging test.The results show that the different extracts from three seaweeds with high antioxidant activities had positively correlated between the ability of scavenging free radical and concentration within a range of certain concentration.And the antioxidant activities were correlated with the contents of total phenolic，total flavonoids and total sugar.At 1.0 mg/mL，the hydroxyl radical scavenging capacity of Sargassum thunbergii（Mert.）O.Kuntze extract from water was best，which was 46 819.97 U/mL；the superoxide anion activity of Codium cylindricum Holmes extract from ethanol precipitate was best，which was 18 571.43 U/L；and the DPPH free radical scavenging capacity of Ishige.okamurai Yendo extract from methanol was the highest，which was 39.28%.Selection of natural antioxidants from the different extracts of Ishige.okamurai Yendo and Sargassum thunbergii（Mert.）O.Kuntze，and developing products with the extracts.