1972 Volume 18 Issue 4 Pages 218-224
In order to elucidate the mechanism of the anticoccidial action of chloro-ethylthiamine, the effect of chloroethylthiamine on the biological systems related to thiamine was examined. Chloroethylthiamine did not influence the activity of thiamine pyrophosphokinase (EC 220.127.116.11) from rat livers and Ehrlich ascites carcinoma cells and also the coenzyme activity of TDP on pyruvate decarboxylase (EC 18.104.22.168) and transketolase (EC 22.214.171.124.) from baker's yeast. On the other hand, chloroethylthiamine exhibited a marked inhibition against thiamine transport mediated by a carrier through biological membranes in Ehrlich ascites carcinoma cells or chick small intestine.
The inhibition of thiamine transport is an exclusive factor for the antithiamine action of chloroethylthiamine detected, indicating that this effect could be responsible for the exertion of the anticoccidial action. In fact, thiamine analogues which exert the anticoccidial action inhibited active transport of thiamine by the small intestine of rats and those which did not depress thiamine transport could not exert any anticoccidial action. These results lead to the conclusion that the anticoccidial action of chloroethylthiamine is due to its ability to inhibit thiamine uptake by the coccidium, Eimeria tenella.