DPPH radical scavenging capacity,TEAC value and main chemical component content were taken as indexes to singled out the seaweed and its active extract with higher content polyphenol and stronger antioxidant activity from ten kinds of seaweeds in Fujian weitou bay.Then, DPPH radical scavenging ability, reducing power and total antioxidant capacity (T-AOC) of the active extract was investigated respectively, preliminary analysis into the effects of metal ion on its antioxidant activity was also studied.The results showed that methanol extract of Ishige okamurai had higher content of polyphenol, higher TEAC value and stronger DPPH radical scavenging ability among 10 seaweeds, ethyl acetate fraction of methanol extract from Ishige okamurai was mian antioxidant active fraction with the EC50 value of DPPH radical scavenging of 0.17mg/mL, which was less than that of BHT(0.23 mg/mL), and with the EC50 value of reducing power of 0.30 mg/mL, which was far less than that of Vit C(0.91 mg/mL),and with T-AOC value of 13.16 U/mg. The effects of metal ion on DPPH radical scavenging activity of ethyl acetate fraction from Ishige okamurai showed that metal ion such as K+,Cu2+, Zn2+,Ca2+,Fe3+ had some synergistic effects, but Na+,Mn2+,Mg2+ had antagonistic effects.%以DPPH自由基清除能力、TEAC值与主要化学成分含量为指标，从福建省围头海域的10种海藻中筛选出总酚含量较高、抗氧化活性较强的海藻及其抗氧化活性部位.进一步对该海藻的抗氧化活性部位进行DPPH自由基清除能力、还原力与总抗氧化能力的测定，初步分析金属离子对其抗氧化活性的影响.结果表明：10种海藻中，铁钉菜甲醇提取物具有较高含量的多酚、TEAC值与较强的DPPH自由基清除能力，乙酸乙酯部位是其主要的抗氧化活性部位.铁钉菜乙酸乙酯部位对DPPH自由基清除的半效应浓度EC50为0.17 mg/mL，小于BHT EC500.23 mg/mL；还原力的EC50为0.30 mg/mL，远远小于维生素C EC500.91mg/mL；总抗氧化能力约为13.16 U/mg.金属离子对铁钉菜乙酸乙酯部位的DPPH自由基清除的影响表现为K+、Cu2+、 Zn2+、Ca2+、Fe3+等的增效作用与Na+、Mn2+、Mg2+等的降效作用.
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