from
The Collaborative International Dictionary of English v.0.48
Xanthine \Xan"thine\, n. Also Xanthin \Xan"thin\ . [Gr. xanqo`s
yellow.] (Physiol. Chem.)
A type of purine obtainable as a white microcrystalline
powder, {C5H4O2N4}, present in muscle tissue, in the liver,
spleen, pancreas, and other organs, and also in urine (in
small quantities) and some urinary calculi, and in the juices
of certain plants; -- so called because it leaves a yellow
residue when evaporated to dryness with nitric acid. It is
also present in guano. Xanthine is closely related to uric
acid.
[Webster 1913 Suppl.]