Xanthin

(zan' -thin) yellow, 1. A leukoma in found in nearly all the ti ues and liquids of the animal economy, and also in many plants; also in minute quantities as a normal constituent of urine. It is formed at the same time with adenin, guanin, and hypo xanthin in the decomposition of nuclein by dilute acids. Guanin is convertible into xanthin, which is thought to be one step lower as an intermediate product of nuclein-decomposition, and nearer the uricacid limit of oxidation. It probably is oxidized in the body as fast as it is formed. It is a colorle powder, almost insoluble in cold water, but readily soluble in dilute acids and alkalies. It is non-poisonous and a muscle-stimulant, especially of the heart. See Leukot/iains, Table of. 2. The name given by Fremy and Cloez to the yellow coloring-matter of plants, which is insoluble in water, but soluble in alcohol, in which respect it is distinguished from Xanthein. See Pigments, Conspectus of.