After the oral administration of nicotinamide to human subjects, two ultraviolet-absorbing compounds have regularly been detected on chromatograms of plasma extracts. The less polar of these, named Compound Y, has been identified as N’-methyl2-pyridone-5-carboxamide (1). In the present communication, evidence is presented that the more polar metabolite, Compound X, is N’-methyl-4-pyridone-3-car...

Epididymal semen was obtained from rams with a fistula present in the vas deferens (Tadmor & Schindler, 1966). It was deproteinized immediately, and the protein-free clear supernatant evaporated to dryness in vacuo at a temperature not exceeding 55\s=deg\C. The residue was taken up with about 10 ml water, and the solution thus obtained used for determination of both amines and amino acids. For ...