抄録
The destruction of dihydrothiamine (DHB_1) in animal bodies on its oral or intraperitoneal administration, was already observed by the author. The author found a thiamineforming factor in homogenates of various animal organs. On incubating DHB_1 with homogenates of heart, liver, spleen and kidney of rats or guinea pigs, transformation of DHB_1 into thiamine which was highest e.g. 9-12% of DHB_1 by kidney homogenates, was observed. The maximal conversion into thiamine by rat liver homogenate was 6% of DHB_1 at the optimum of pH and temperature (4.5 and 37℃) in 6 hours, while decomposition of DHB_1 was quick ; less than 10% of DHB_1 was found unchanged in 3 hours. The active substance capable to oxidize DHB_1 into thiamine was effective only at the presence of oxygen or air, and it lost most of its activity by boiling, dialysis or addition of SH-attacking agents such as potassium cyanide, sodium azide, or iodoacetate. Some of its activity was kept after precipitation by ammonium sulfate or acetone. Although this thiamine-forming factor seemed to be enzymatic, it was effective only in acid medium (pH 4.5) with a poor yield of thiamine. It will be most probable that DHB_1 is quickly decomposed or excreted partly unchanged into urins before its meager transformation into thiamine.
