REACTION MECHANISMS OF THIAMINE WITH THERMOSTABLE FACTORS
1974 年 20 巻 5 号 p. 351-362
詳細
1974 年 20 巻 5 号 p. 351-362
Distributions of thermostable thiamine-inactivating factors in about 10 kinds of ferns and brackens and 42 kinds of other plants were investigated. It was observed that besides ferns and brackens, some plants (most of them greenish or yellowish in color) had thermostable thiamine-inactivating activities, and that shiitake, okra, fukinoto (butterbur flower stalk), diluted water extract of green tea, and diluted coffee had activities which oxidized thiamine into thiamine disulfide.
The present study showed that one of the factors isolated from fern 3, 4-dihydroxycinnamic acid (caffeic acid) and catechol distributed in plants accelerated decomposition of thiamine at pH 7-7.5 into 2-methyl-4-amino-5-aminomethyl-pyrimidine, decomposing the thiazole moiety, probably into γ-aceto-γ-mercapto-propylalcohol and formic acid. However, some flavonoids, especially 6, 7, 4'-trihydroxyisoflavone (Factor 2) were proved to have the ability to accelerate oxidation of thiamine into thiamine disulfide at pH 7.5. Estimation was made of the decomposition products of thiamine with caffeic acid, catechol and Factor 2 under certain conditions.
