The F2 Excretion of Normal Men on Different Levels of Niacin Intake.

Abstract

Najjar and his collaborators1V2 reported the presence in urine from normal individuals of a fluorescent substance which they called F2.This compound was excreted in fairly large amounts when the niacin intake was high. In cases of pellagra the excretion of F2 was diminished or even zero in some cases. When large amounts of niacin were ingested by normal individuals or during the course of pellagra therapy, the F2 excretion increased. Their evidence indicated that this fluorescent substance was related to the metabolism of nicotinic acid.Recently both the Johns Hopkins group3v4 and Huff and Perlzweig6 have shown by means of chemical isolation that the fluorescent substance is a derivative of niacin, suggesting that F2 is N-methylnicotinamide or some compound closely related to it. a generous supply of pure vitamins. gNajjar, V. A., and Wood, R. W., PROP. SOP. ZNajjar, V. A,, and Holt, L. E., Jr., Science, 3Najjar, V. A., Scott, D. B. M., and Holt, L. E., 1Najjar, V. A., and White, V., Science, 1944, 5 Huff, J. W., and Perlzweig, N7. A., Scienc-c, __ EXP. BIOL. AND MED., 1940, 44, 386. 1941, 93, 20. Jr., Science, 1943, 97, 537. 90, 284. 1943, 97, 538.zweig.? Recently Najjar published another modification? Some of our results with these procedures have been reported in a preliminary note? Experimental. As a part of a comprehensive study of the B vitamido 4 normal young men were maintained for a period of 161 days on a diet which supplied an average of 12.4 mg of niacin per day. During the same period 4 other men were given the same diet plus an additional 10 mg of niacin. This was followed by a period of 32 days when the niacin intake in the diet was reduced to 0.12 mg per day. The niacin in the diet was determined by the microbiological method.ll Twenty-four-hour urine samples were collected throughout the period at intervals of several days. These samples were preserved by adding 5 ml glacial acetic acid and 5 ml toluol to the collection bottles. In most cases the analyses were made on the same day the collection was completed.Throughout the first dietary period, the urines were analyzed by the original method of Najjar, et d." This method was slightly modified to permit the determination of thiamine and F2 on the same eluate from the zeolite column. When the severely restricted diet was started, the method of Huff and Perlzweig7 was used. Najjar informed us of his modified procedures after all of these analyses were completed.The procedures of Najjar et uLG and NajjarS 0 Najjar, V. A., Stein, H.