Effect of Ingestion of Various Pyridine Compounds on Excretion of Specific Fluorescent Substances in Urine. ∗

Abstract

In previous publications 1 , 2 attention has been called to 2 fluorescent substances in the urine, the concentrations of which appear to depend upon the body stores of nicotinic acid. The composition of these 2 substances which we have designated F₁ and F₂ is as yet unknown. They are characterized by their fluorescence with ultraviolet light, F₁ having an emission spectrum ranging from 4,000 to 4,800 angstrom units with a maximum at 4,350 Å, and F₂ having an emission spectrum ranging from 4,200 to 5,400 Å with a maximum at 4,550 Å. With suitable extraction procedures the excretion of these 2 substances can be measured quantitatively with a fluophotometer. We have found that F₁ is normally present in relatively small quantity in the urine but increases markedly in pellagra. F₂, on the other hand, is present in greater quantity under normal conditions but disappears in pellagra. The administration of nicotinic acid to a pellagrin causes a prompt reduction of F₁ and the reappearance of F₂. Similarly, the administration of nicotinic acid to a normal individual causes F₂ to increase well beyond the normal limits. To explain these facts, we have suggested the hypothesis that F₁ is converted into F₂ through the agency of some nicotinic acid containing enzyme. In nicotinic acid deficiency, failure of such conversion causes F₁ to accumulate and F₂ to disappear, whereas in the presence of this catalyst, F₂ is formed in quantities which bear some relation to the supply of nicotinic acid.

It seemed of interest to ascertain the effect of various pyridine and pyrazine compounds on the excretion of F₂ in human subjects in order to determine if there were any parallelism between this property and the ability to cure pellagra. The compounds chosen for testing were: nicotinic acid, nicotinamide, sodium nicotinate, dinicotinic acid, trigonelline, 2-6 dimethyl nicotinic acid, quinolinic acid, pyrazine monocarboxylic acid, pyrazine, 2,3-dicarboxylic acid, pyridine β-carboxylic acid diethyl amide (coramine) and sulfapyridine.