Abstract
It was previously reported by us that DOB_1 had no B_1 antagonistic effect on rats when given subcutaneously with B_1 (Vitamins 28,549,1963). Throughout the present study, it was observed that DOB_1 had competitive inhibitory effect when given orally with B_1,while it had no effect when either one of B_1 or DOB_1 was given subcutaneously and the other orally. From these results above mentioned, it is suggested that DOB_1 inhibits specifically the absorption of B_1 at the intestinal tract. To examine the B_1 antagonistic effect of DOB_1 at B_1 relating enzyme system, rat liver thiamine pyrophosphokinase was purified according to Mano's method. Whereas the presence of pyrithiamine at a molar ratio to B_1 of about 8 : 1 resulted in a significant inhibition, DOB_1 at levels 100 times those of B_1 was found to be ineffective.
