2000 Volume 6 Issue 3 Pages 186-191
Variegatic acid (3,3',4,4'-tetrahydroxypulvinic acid, VA) which causes a blueing phenomenon in mushrooms was isolated from Boletus subvelutipes. B. subvelutipes contains 916 mg VA/100 g dry weight of the fruit body. A mixture of VA and acetone powder from B. subvelutipes caused removal of methyl mercaptan (MeSH) after blueing. Optimum pH for the blueing activity by polyphenol oxidase from B. subvelutipes was 5.0 and a high deodorizing activity was observed around the optimum pH. The rate of MeSH removal with VA in 0.4 M potassium phosphate buffer (pH 8.0) was about 36 times as high as that with (−)-epigallocatechin gallate, which has been reported to have the highest deodorizing activity among tea catechins. We isolated several kinds of conjugates of VA molecules with 1-3 MeSH molecules. These results suggest that VA has a high deodorizing activity because it can easily be oxidized and can bind to MeSHs at 6 positions in the 2 dihydroxybenzene rings of VA.
