Chemical Studies on Antioxidative Activities of Tree Phenolic Extractives and Their Functions for Higher Utilization.

近年来，木材抽提物的各种生物活性被人们所关注，以更高、更有效地利用树木资源。其次，对木材酚类成分的抗氧化活性进行了研究。目前已检测出80多个化合物，并从中筛选出许多具有抗氧化活性的化合物。本研究的目的是重新精确地比较天然黄酮类化合物的抗氧化活性，并解释黄酮类化合物的反应机理，因为迄今为止还没有揭示其与酚类化合物的反应机理。首先，在相同位置上具有多个羟基的黄酮类化合物的自由基捕获能力的细微差异，对DPPH自由基的影响。即，圣草酚，槲皮素和紫杉叶素的抗氧化活性给出了具体的自由基捕获常数。其次，以槲皮素及其糖苷（芦丁）为原料，合成了多种槲皮素甲基衍生物，并进行了抗氧化反应机理的揭示实验。在主要实验之前，如上所述测定它们的自由基捕获常数。以3-羟基黄酮和3-甲氧基黄酮为底物，在体外与2，2 ′-偶氮二（2，4-二甲基戊腈）（AMVN）反应。然后，获得和/或检测反应产物。通过一系列的实验结果，提出了3-羟基黄酮（黄酮醇）的抗氧化反应。

Recently, various bioactivities of wood extractives are noted for higher and effective uses of tree resources. Then, we are studiing on the antioxidative activity of wood phenolic constituents. Over 80 constituents had been tested already, and many constituents with high antioxidative activity had been found out. Also, the relationship to potency and chemical structure on the generation of antioxidative activity.On the present study, the objects were to compare precisely the activity of natural flavonoids again, and to explain the reaction mechanism of flavonoid, because the mechanism with phenolic compounds had not been revealed so far.At first, the fine difference of radical capturing abilities among flavonnoids with plural hydroxyl groups at same positions, on 1,1-diphenyl-2-picrylhydragil (DPPH) radical could be clarifed by the stopped flow method. Namely, antioxidative activities for eriodictiol, quercetin and taxifolin were given in concrete radical capturing constants. Nextly, various methyl derivatives of quercetin were prepared from quercetin and its glycoside (rutin) for revealing experiment of antioxidative reacttion mechanism. Before main experiment, their radical capturing constants were determined as mentioned above. While using 3-hydroxyflavone and 3-methoxyflavone as substrate, the reaction with 2,2'-azobis-(2,4-dimethylvarelonitrile) (AMVN) in vitro was undertaken. Then, the reaction products were obtained and/or detected. Furthemore, the change of products with time were determined by HPLC.Accordingly, as a results of a series of experiments, the antioxidative reaction 3-hydroxyflavone (flavonol) can been proposed.