Comparative Studies of the Metabolism of 14C-Pyrimidine-labeled Thiamine, 14C-Thiazole-labeled Thiamine and 35S-labeled Thiamine in the Rat

Abstract

The nature of the urinary products of thiamine catabolism was studied in rats, using 3 species of radioactive thiamine. Adult rats were injected with ¹⁴C-pyrimidine-labeled thiamine, ¹⁴C-thiazole-labeled thiamine, or ³⁵S-thiazole-labeled thiamine, and the chromatographic patterns of urinary radioactive metabolites were compared. Of the 4 major unidentified radioactive metabolites found in urine (more than 20 were detected), all contained the pyrimidine ring and at least a portion of the thiazole ring. One compound contained the 2-carbon of thiazole but not the sulfur atom. One compound (designated as V-1) contained both moieties of the molecule, did not support the growth of Lactobacillus viridescens, was not converted to thiochrome, and was not cleaved by the bisulfite reaction. There was no evidence for the presence of free thiazole or thiazole-like compounds in the urine. A speculative sequence for the catabolism of thiamine by the rat based on these data is presented.