[zan-theen, -thin]
noun Biochemistry, Chemistry.
a crystalline, nitrogenous compound, C 5 H 4 N 4 O 2 , related to uric acid, occurring in urine, blood, and certain animal and vegetable tissues.
any derivative of this compound.

1855–60; < French; see xantho-, -ine2

Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
Cite This Source Link To xanthine
World English Dictionary
xanthine (ˈzænθiːn, -θaɪn)
1.  a crystalline compound related in structure to uric acid and found in urine, blood, certain plants, and certain animal tissues. Formula: C5H4N4O2
2.  any substituted derivative of xanthine, esp one of the three pharmacologically active methylated xanthines, caffeine, theophylline, or theobromine, which act as stimulants and diuretics

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
Cite This Source
American Heritage
Medical Dictionary

xanthine xan·thine (zān'thēn', -thĭn)

  1. A yellowish-white crystalline purine base that is a precursor of uric acid and is found in blood, urine, and muscle tissue.

  2. Any of several derivatives of this compound.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Cite This Source
American Heritage
Science Dictionary
xanthine   (zān'thēn', -thĭn)  Pronunciation Key 
  1. Any of various purines having two oxygen atoms attached to the six-member ring of carbon and nitrogen atoms. Xanthines include caffeine, theophylline (a toxic alkaloid found in tea leaves), and theobromine (a toxic alkaloid found in cocoa).

  2. The simplest of this class of compounds, forming yellowish-white crystals. It is produced in the body as an intermediate stage in the breakdown of purines to uric acid. It is also found in blood and in certain plants. Chemical formula: C5H4N4O2.

  3. Any of several derivatives of this compound.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
Cite This Source
Example sentences
Allopurinol is a xanthine oxidase inhibitor that blocks uric acid production.
Copyright © 2014 Dictionary.com, LLC. All rights reserved.
  • Please Login or Sign Up to use the Recent Searches feature