STUDIES ON THE CHEMICAL DIAGNOSIS OF PELLAGRA (NICOTINIC ACID DEFICIENCY) 1

Abstract

The application of the cyanogen bromide reaction yields values for blood nicotinic acid higher than those reported by other chemical methods and in good agreement with detns. by different biological methods. Confirming most of the reports of detns. by biological methods, no significant difference was found in the nicotinic acid contents of the bloods of normal and deficient subjects. By various types of dosing for "saturation tests," it was demonstrated that nicotinic acid is not removed from the blood of pellagrins faster than from that of normal subjects. The detn. of nicotinamide in urine is complicated by the presence of other pyridine compounds which reacted similarly. Trigonelline, the methylated form in which the greater part of nicotinic acid is excreted, occurs preformed, is without antipellagra activity, and is widely distributed in vegetable materials, coffee predominately. Depending upon the individual, a variable fraction of nicotine reacting like nicotinic acid may be excreted. A larger fraction of the nicotinic acid excreted behaves on hydrolysis like trigonelline. The hydrolytic behavior of trigonelline permits its differentiation from other pyridine compounds and its semi-quantitative, analysis. 24 hr. urine specimens collected during abstinence from coffee, tobacco, tea and chocolate show a secretion of nicotinic acid averaging distinctly less in deficient than in normal subjects, but not consistently less. The difference in the urinary excretion of trigonelline in normal and deficient subjects is much greater and much more consistent. With a standardized basal regime and a more quantitative recovery, the urinary excretion of trigonelline may be the best chemical indication of nicotinamide deficiency.