Abstract
As the case of the investigation on the antagonistic effect of vitamin B_6 relating compounds upon the toxication caused by injection of toxopyrimidine, the preventing action of niacin and some of its derivatives against the toxic action caused by injection of the lethal dose of acetylpyridine to mice was examined. While niacin and niacin diethylamide were found to be inactive, niacinamide was shown to be very effective in accordance with the description of Kaplan et al.. Diphosphopyridine nucleotide was, however, found to be very weakly active contrary to their results. Triphosphopyridine nucleotide was also scarcely effective. Toxopyrimidyl niacinamide was found to inhibit the action of acetylpyridine in an equimolecular amount to that of niacinamide, though the nitrogen of its pyridine nucleus is quaternary like that of DPN or TPN. In order to investigate whether toxopyrimidyl niacinamide could antagonize toxopyrimidyl acetylpyridine, the latter compound was synthesized and investigation on its properties was carried out. The velocity of its toxic action was much higher than that of acetylpyridine itself and the symptom was different from that by toxopyrimidine. The death by the injection of toxopyrimidyl acetylpyridine could not be prevented by the injection of toxopyrimidyl niacinamide.
