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[si-truh-leen] /ˈsɪ trəˌlin/
noun, Biochemistry
an amino acid, NH 2 CONH(CH 2) 3 CHNH 2 COOH, abundant in watermelons and an intermediate compound in the urea cycle.
1930; < New Latin citrull(us) the watermelon genus (Medieval Latin citrul(l)us, citrolus, Latinization of South Italian citrulo, Tuscan citri(u)olo < Late Latin citrium watermelon (derivative of Latincitrus (see citrus); apparently in reference to the citroncolored fruit of some types of watermelon), with -uolo < Latin -eolus) + -ine2 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for citrulline
  • citrulline is an amino acid first isolated from watermelon juice.
  • citrulline has potential antioxidant and vasodilatation roles.
  • To determine the level of citrulline to produce a given amount of arginine in healthy volunteers and surgical patients.
  • Nitric oxide is made from other common compounds arginine and citrulline that are normally found in our bodies.
British Dictionary definitions for citrulline


an amino acid that occurs in watermelons and is an intermediate in the formation of urea. Formula: NH2CONH(CH2)3CHNH2COOH
Word Origin
C20: from Medieval Latin citrullus a kind of watermelon, from Latin citron, referring to its colour
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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citrulline in Medicine

citrulline cit·rul·line (sĭt'rə-lēn')
An amino acid produced as an intermediate in the conversion of ornithine to arginine during urea formation in the liver.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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citrulline in Science
An amino acid originally isolated from watermelon, occurring mostly in the liver as an intermediate in the conversion of ornithine to arginine during urea formation. Chemical formula: C6H13N3O3.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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