Effect of Indole on the Determination of N′-Methylnicotinamide

Abstract

Observations have suggested that indole was not being utilized to form nicotinic acid derivatives, but was interfering with the fluorometric detn. of N[image]-methylnicotinamide (MNA). To test this, urine from rats fed indole was extracted to remove indole prior to estimation of MNA. Also, the effect of indole, tryptophane, and anthranilic acid on the measurement of MNA was detd., and the effect of indole was also tested in the presence and absence of urine. Indole tested in the absence of urine showed some fluorescence measured as MNA. This effect was eliminated by extraction of indole prior to the detn. of MNA. Anthranilic acid or tryptophane failed to show this interference. Ether extraction of urine from rats fed indole reduced somewhat the values for MNA, but did not reduce them to an extent whereby the. effect of feeding indole on the amts. of the methylated derivative in the urine was negated. Controls fed the basal diet or basal diet plus tryptophane showed no reduction attributable to ether extraction of the samples. Similarly, MNA was not extracted by ether. It appears that extracting urine samples with ether removes only a part of the interfering substances formed when indole is fed. There is no evidence that indole interferes with the microbiologic detn. of nicotinic acid.