ORAC和DPPH测定法比较评估茶浸液抗氧化能力:总多酚和个别儿茶素含量之间的关系。

PubMed ID
发表日期 2010年Mar月

原始出处 国际食品科学与营养杂志
International journal of food sciences and nutrition
作者 Roy  Molay K  Koide  Motoki  Rao  Theertham P  Okubo  Tsutomu  Ogasawara  Yutaka  Juneja  Lekh R 

文献标题 ORAC和DPPH测定法比较评估茶浸液抗氧化能力:总多酚和个别儿茶素含量之间的关系。
ORAC and DPPH assay comparison to assess antioxidant capacity of tea infusions: relationship between total polyphenol and individual catechin content.

文献摘要

市售茶汤是目前市场上用于制备瓶装茶饮料和茶补充剂的儿茶素的主要来源。在本研究中,我们通过氧自由基吸收能力(ORAC)和2,2-二苯基-1-吡啶酰肼(DPPH)自由基清除能力(DRSC)测定了五种茶浸液的总抗氧化能力(TAC),采用比色法测定总多酚含量,高效液相色谱法测定单个儿茶素含量。四种主要的茶儿茶素也进行了TAC分析,以揭示茶浸液的不同抗氧化行为,从而得出ORAC和DRSC方法。茶汁中总多酚或总儿茶素含量与DRSC的相关系数分别为1.0和0.99。而ORAC活性则与总多酚和总儿茶素含量相关。测定各茶儿茶素的TAC,表儿茶素的ORAC是表儿茶素没食子酸酯的7倍,表儿茶素没食子酸酯的DRSC活性显著高于表儿茶素(P<0.05)。通过评估结构-活性关系,本研究进一步揭示了表没食子儿茶素和表没食子儿茶素没食子酸酯的ORAC值低于非3'-OH对应物,如表儿茶素和表儿茶素没食子酸酯。此外,与DRSC不同,OH取代的数量与观察到的ORAC值相关性很差。总的来说,这项研究的结果使我们能够假设,与DPPH分析相比,ORAC分析中具有较低TAC值的物质可能与在水缓冲液中产生活性氧物种的促氧化作用有关,在生理pH下,我们还提出,与在ORAC试验中显示出比DPPH试验中更低TAC值的物质相比,在ORAC试验中显示出比DPPH试验中更高TAC值的物质是强大的促氧化剂。


Commercially available tea infusions are the major source of catechins for preparing bottled tea beverages and tea supplements available in the market today. In the present study, we analyzed five tea infusions to measure the total antioxidant capacity (TAC) by oxygen radical absorbance capacity (ORAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity (DRSC) assays, total polyphenol content by the colorimetric method and individual catechin content by high-performance liquid chromatography. Four major tea catechins were also analyzed for their TAC to reveal differential antioxidant behavior of the tea infusions, resulting in the ORAC and DRSC methods. The correlation coefficients between DRSC and the total polyphenol or total catechin content of the tea infusions were 1.0 and 0.99. However, the values fall to 0.73 and 0.69, respectively, while the ORAC activity was correlated with total polyphenol and total catechin content. Determining the TAC of individual tea catechins showed that ORAC of epicatechin was seven-fold higher than that of epigallocatechin gallate; on the contrary, epigallocatechin gallate showed significantly (P < 0.05) stronger DRSC activity than epicatechin. By evaluating the structure-activity relationship, this study further revealed that OH substitution at the 3' position in pyrogallol moieties contributes to the lower ORAC value of epigallocatechin and epigallocatechin gallate comparing with their non-3'-OH counterparts, such as epicatechin and epicatechin gallate, respectively. Also, numbers of OH substitutions were poorly correlated with the observed ORAC value unlike the DRSC. Overall, results of this study enabled us to hypothesize that substances having a lower TAC value in the ORAC assay compared with that in DPPH assays may pertain to a pro-oxidant effect by generating reactive oxygen species in an aqueous buffer, at a physiological pH. We also propose that substances exhibiting lower TAC value in the ORAC assay compared with that in the DPPH assay are powerful pro-oxidants compared with the substances showing a higher TAC value in the ORAC assay than that in the DPPH assay.


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