Nicotinamide metabolism in mammals

Publisher Website
Google Scholar
Abstract
The metabolism of nicotinamide derivatives in men, dogs, cats, rats, rabbits and guinea pigs was studied under normal conditions and after admn. of nicotinamide, nicotinic acid, nikethamide and, in some instances, of nicotinamide methochloride and nicotinuric acid. The metabolites tested for were nicotinamide, nicotinic acid, nicotinuric acid, trigonelline and nicotinamide methochloride. Under normal conditions men eliminate nicotinamide, nicotinic acid and mainly nicotinamide methochloride, dogs and rats nicotinamide and nicotinamide methochloride, cats only the latter . compound, rabbits nicotinic acid and guinea pigs none of these compounds. No nicotinuric acid or trigonelline was found in the urine. Rabbits and guinea pigs, however, eliminate small amts. of an unknown substance, giving a positive reaction by the acetone method. Extradietary nicotinamide was eliminated by men almost exclusively as nicotinamide methochloride, by dogs, cats and rats partly as nicotinamide, partly as nicotinamide methochloride, by rabbits as nicotinamide, nicotinic acid and trigonelline and by guinea pigs as nicotinic acid; in the last-named species the unknown compound giving a positive reaction with the acetone method was slightly augmented. Nicotinic acid was eliminated by men mainly as nicotinamide methochloride and to a very small extent unchanged and as nicotinamide; by dogs, cats and rats in the form of all 3 metabolites, by rabbits partly unchanged, partly as trigonelline and by guinea pigs unchanged. Nikethamide is broken down to nicotinamide and accordingly further metabolized by all species. In rabbits after the injn. of nikethamide, purplish blue fluorescent pigments occur in the urine, 3 of which have been isolated. Men, dogs, cats and rats aminated nicotinic acid; rabbits and guinea pigs deaminate nicotinamide; all species except guinea pigs methylate the metabolites to nicotinamide methochloride or trigonelline, respectively; nicotinuric acid is broken down by dogs and rats to nicotinic acid and nicotinamide and cannot, therefore, be an end product of metabolism, while nicotinamide methochloride is eliminated unchanged by rats. DL-Methionine has no constant effect on the metabolism of the various derivatives in rats and is toxic to these animals in larger doses.

This publication has 22 references indexed in Scilit: