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

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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.