Abstract
Previously, the author isolated quinoid like yellow pigments as a thermostable antithiamine factor (SF) from horsetail. The thiamine decomposing activity of several oxyquinoid pigments was, therefore, studied in this experiment. The decomposing activity of p-henzoquinone resembled the one of flavonoid pigment in reactive conditions such as pH, temperature and time. The decomposing activity of 10μg of SF was found in 5.0μg p-benzoquinone, 4.7μg naphtoquinone, 4.9μg anthraquinone, 1.0〜1.7μg monohydroxyanthraquinone, 1.8〜2.5μg dihydroxyanthraquinone, and 2.1〜3.8μg trihydroxyanthraquinone. When the decompsoing products of thiamine by SF were studied by paper chromatography, the production of thiochrome was observed in the case of p-benzoquinone, but thiochrome was not produced by flavonoid. It was, therefore, supposed that each SF might have their own thiamine decomposing mechanism.
