海带抗氧化多酚的制备及活性研究

用1：1的氯仿：甲醇超声提取海带成分，并用石油醚、乙酸乙酯和正丁醇依次进行萃取，利用DPPH法、邻二氮菲-Fe^2＋氧化法、铁氰化钾还原法和邻苯三酚自氧化进行抗氧化实验，同时与抗氧化剂2，6-二叔丁基对甲酚（BHT）和没食子酸（GA）进行对照。结果显示海带提取物与各萃取组分均具有较强的抗氧化能力，其中乙酸乙酯提取物（EA）抗氧化活性最强。在50μg／mL浓度时，EA清除DPPH自由基、羟自由基、超氧阴离子自由基的能力和还原能力均高于抗氧化剂BHT，且清除超氧阴离子自由基的能力也高于CA；另外，Aqueous组分在所有测定浓度下清除羟自由基能力均高于GA，清除O2的能力也高于BHT。海带各提取物总酚含量的分析表明总酚含量与抗氧化活性之间具有一定的相关性，总酚含量高其抗氧化能力也相应提高，表明多酚是提取物中重要的抗氧化成分。4种抗氧化方法的比较表明DPPH法的相关系数最高（R=0．987），是海带体外抗氧化实验最有效的方法。

Evaluation of Antioxidant Activities of Phlorotannins from Laminaria japonica

Seaweeds have long been used in food diets, as well as traditional remedies in China. Recently, they have received significant attention for their potential as natural antioxidants. At present, study on the antioxidant active constituents of L. japonica were mainly focused on the bioactive polysaccharides and oligosaccharides, but the secondary metabolites, especially the phenols was paid little attention. In our study, L. japonica was extracted with methanohchloroform（hl） and the active extract （MC） was further purified by liquid-liquid partition with petroleum ether, ethyl acetate and n-butanol to afford four fractions （PE, EA, BuOH and Aqueous）. Antioxidant activity of the extraction and fractions was evaluated in four different assays, namely, the 1,1-diphenyl-2-picrylhydrazyl （DPPH） radical scavenging assay, the phenanthroline Fe^2＋ reaction system, the potassium ferricyanide reduction methods and antioxidation reaction system of the pyrogallol, and compared with that of butylated hydroxytoluene （BHT） and gallic acid （GA）. The experimental results showed that the EA fraction exhibited the highest antioxidant activity at all of three concentration levels tested. At all of four concentration levels tested （from 50 to 500 μg/mL）, the EA fraction showed much higher scavenging activity （DPPH and OH） and reducing power than that of BHT, and much higher scavenging 05- activity than that of BI-IT and GA. Aqueous fraction showed much higher scavenging OH activity than that of GA and scavenging 02- activity than that of BHT. The total phenolic content was determined using the Folin-Ciocalteu, and statistical analysis indicated in vitro antioxidant activity of total extract and fractions showed an increase with increasing phenolic content indicating the dose dependency of these properties. Also, the efficiency of different methods on in vitro antioxidative activities of total extract was analyzed and the DPPH radical scavenging assay showed the maximum sensitivity. The findings of this work japonica extract in possible therapy of diseases related to may contribute to a rational basis for the use of L. oxidative stress or as a dietary supplementary has beneficial effects for human health.