Abstract
In the course of some studies on the excretion of thiamin in urine by means of the thiochrome method, using the procedure of Hennessy and Cereeedo, 1 it was noted that treatment of the KC1 eluate of urine with alkali, even in the absence of ferricyanide, yielded a small amount of a substance soluble in butyl alcohol which gave a bluish fluorescence with ultraviolet light. This fluorescence could be distinguished from that given by thiochrome even with the naked eye, being a whitish blue without any tinge of violet. Specimens of urine from a large series of normal individuals of various ages were found to exhibit such fluorescence in slight degree. A patient receiving nicotinic acid therapy, however, was found to excrete it in large amount, suggesting that nicotinic acid was the precursor of this substance. Following this observation the effect of taking nicotinic acid was studied in normal individuals, and it was found that a dose of 50 mg of nicotinic acid, given to an adult, produced a prompt increase in the excretion of the unknown material. An increase in its concentration in the urine could be detected within an hour, and persisted for 4 to 6 hours.
We have attempted to identify the unknown urinary constituent by studies of the fluorescence of 27 different pyridine derivatives.† These compounds were dissolved in 25% KC1 solution, both with and without treatment with alkali; the aqueous solution was then extracted with butyl alcohol, the alcoholic extract being tested for fluorescence with ultraviolet light. The following substances were tested:
Most of these compounds gave negative results. Both compounds containing a 5-amino substitution in the pyridine ring gave a fluorescence with an indigo blue tint resembling that of thiochrome, rather than that of the unknown; alkali was not needed to bring this out.
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