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The lyophilization of the solution extracted from 60 percent of acetone applied to persimmon leaves, the compounding process in accordance with the solution´s concentration, and the gel filteration through Sephadex G-50 of biologically activated substances obstructing enzyme activity, such as tyrosinase, xanthine oxidase, and angiotesin converting enzyme (ACE) led to the assumption that polyphenol was the compound serving as biologically activated substances obstructing enzyme activity. Xanthine oxidase involved in pruine metabolism oxidizes hypoxanthine to xanthine and xanthine to uric acid. In the continuous study for natural compound, nine flavan-3-ois have been isolated from the persimmon leaves. The structures of (+)-catechin, (+)-gallocatechin, procyanidin B-1, pyrocyanidin C-1, prodelphinidin B-3, gallocatechin-(4α→8)-catechin, procyanidin B-7-3-O-gallate, procyanidin C-1-3´-3´´-3´´´-O-trigallate and (-)-epigallocatechin-(4β→8)-epigallocatechin-(4β→8)-catechin were established by NMR and their inhibitory effect on xanthine oxidase activity was investigated. Procyanidin C-1-3´-3´´-3´´´-O-trigallate showed 94%, 90.69%, 80.90% inhibition at 100(μ)M and inhibited on the angiotension converting enzyme respectively. Procyanidin B-7-3-O-gallate and procyanidin 1-3´-3´´-3´´´-O-trigallate showed 66%, 63% inhibition at 100(μ)M and inhibited on the xanthine oxidase competitively. Procyanidin C-1-3´-3´´-3´´´-O-trigallate showed 70% inhibition at 100(μ)M inhibited on the thyrosinase competitively.
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