Isolation and identification of two new nicotinamide metabolites.

Two previously unreported metabolites of nicotinamide have been discovered as urinary excretion products of rats following intraperitoneal injection of nicotinamide-7-i4C or nicotinic acid-7-W. These compounds have been identified as 6-hydroxynicotinamide and 6-hydroxynicotinic acid by comparison of ultraviolet, infrared, and mass spectra and behavior on chromatography and electrophoresis with that of the authentic compounds. These compounds are also formed from nicotlnamide and nicotinic acid by germ-free rats, indicating that they are produced in the tissues rather than by the intestinal flora. From 0.6 to 1.2 % of the injected dose of either nicotinic acid or nicotinamide is excreted as 6-hydroxynicotinic acid and 6-hydroxynicotinamide.