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(organic chemistry)
C5H4N4O2 A toxic yellow-white purine base that is found in blood and urine, and occasionally in plants; it is a powder, insoluble in water and acids, soluble in caustic soda; sublimes when heated; used in medicine and as a chemical intermediate. Also known as dioxopurine.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



(2,6-dioxopurine) an intermediate product of the metabolic degradation of purine bases. Its structural formula is

Xanthine forms yellow crystals. Its melting point is 220°C (with decomposition), and its molecular weight is 152.12. Xanthine dissolves poorly in water and better in alcohol. It displays the properties of a weak acid and a weak base. Widely found in nature (in small amounts), it is formed during the hydrolytic deamination of guanine or as a result of the aerobic oxidation of hypoxanthine in the presence of the enzyme xanthine oxidase. This enzyme also oxidizes xanthine to the final product of purine metabolism in man—uric acid—and this serves as a basis for xanthine determination. When this stage of xanthine metabolism is disrupted, xanthine accumulates in the body, primarily in the form of calcium salts (urinary calculus).

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
A third explanation of xanthine action is that these agents cause the production and release of endogenous catecholamines, which in turn could cause muscle tremor, tachycardia, and bronchial relaxation.
Eventually their structure formula was determined and they were also found to be derivatives of Xanthine, but with only two methyl groups in different positions on the side chains; one was named Theobromine and the other Theophylline.
The compound of choice was to have one of the-methyl groups replaced by a longer side chain containing an oxygen atom with the rest of the molecule being a di-methyl Xanthine. Effectiveness of this new compound was demonstrated by the rabbit ear test, wherein the flow of blood from a priced ear of a rabbit given the medication was several times greater than an unmedicated animal.
In this day and age, emphasizing its identity as a Xanthine derivative would be practically a kiss of death with all anticaffeine propaganda prevalent.
They could have called it a derivative of di-oxo-purine, since this is an alternate name for Xanthine. But Purine is a protein decay product and has strong negative connotations.