The differential determination of benzoylthiamine and thiamine in biological materials

Abstract

Many thiamine derivatives containing a benzoyl group on the thiazole ring have been synthesized recently. These compounds are being used clinically in a variety of disorders thought to be thiamine-related, because they are more readily absorbed than thiamine (1–9). Several authors have suggested the possibility that benzoylthiamine might be formed in animal tissues after administration of these drugs (10–15). Because of the difficulty of separation or differential determination of benzoythiamine and thiamine, the formation of this compound in animal tissues after the administration of precursors has not been completely clarified. Since benzoylthiaminc is strongly toxic to animals (16), investigation of its biosynthesis may be clinically important. The usual fluorometric method for the determination of thiamine (17) cannot differentiate between benzoylthiamine and thiamine because cyanogen bromide in sodium hydroxide converts both compounds to thiochrome (4). In this report we represent a modification which permits a differential determination of the two compounds.