Biological Activities of S-(α-Acyloxyalkyl) thiamines and Other Thioether Type Thiamine Derivatives

Abstract

Of the tested thioether type thiamines, S-acetoxymethyl-O-acetylthiamine (BD 57), S-benzoyloxymethylthiamine (BD 76) and S-(1-benzoyloxyethyl) thiamine (BD 78) showed full thiamine activity while S-acetoxythiomethylthiamine (BD 116) and S-(1-benzoyloxybutyl) thiamine (BD 77) showed 81 and 17% of activity of equivalent mole of thiamine hydrochloride, respectively. BD 57, 76 and 78 were enzymatically converted into thiamine by liver microsomal fraction with ease in the describing order but BD 77 was hardly converted. These compounds were not uptaken by red blood cells in in vitro experiment. Oral administration of BD 57 to dogs caused much higher thiamine levels in blood, especially in blood cells, as compared with administration of thiamine hydrochloride. About 40 to 50% of the injected BD 57, 76, 78 or 116 were excreted as thiamine into the 24 hr urine, while about 30% were excreted after oral administration.