Homogentisic Acid

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homogentisic acid

[¦hä·mə‚jen¦tiz·ik ′as·əd]
C8H8O4 An intermediate product in the metabolism of phenylalanine and tyrosine; found in excess in persons with phenylketonuria and alkaptonuria.
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 It might be outdated or ideologically biased.

Homogentisic Acid


an intermediate product of the decomposition of the cyclic amino acids phenylalanine and tyrosine in the animal or human body. In the hereditary disease alkaptonuria, which is expressed in a disturbance of the metabolism of these amino acids, the process stops at the stage of homogentisic acid formation because of an absence of homogentisic acid oxidase, and homogentisic acid is discharged with the urine.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
The numerous reports on alkaptonuria are limited to degenerative manifestations in joints, but there are very few reports of the effects of the deposition of homogentisic acid in tendons leading to spontaneous rupture.
Alkaptonuria (AKU) is a rare metabolic, autosomal recessive disorder in the phenylalanine and tyrosine catabolic pathway that is characterized by the accumulation of homogentisic acid (HGA; homogentisic aciduria) in the body, especially in the connective tissues (cartilage, tendons, and ligaments) (1) Alkaptonuria is caused by mutations in the homogetisate 1.2-dioxygenase gene (HGD), which lead to a lack of HGD enzyme activity.
Fifteen standard phenolic compounds, including gallic acid, pyrogallol, homogentisic acid, protocatechuic acid, (+) catechin, chlorogenic acid, caffeic acid, vanillin, ferulic acid, naringin, resveratrol, naringenin, hesperetin, formononetin, biochanin-A were purchased from Sigma Aldrich and used for calibration curves.
Sbou' explained that Alkaptonuria is caused by deficiency of the enzyme homogentisic acid oxidase (HGO), as a consequence of the enzymatic block, the homogentisic acid (HGA) accumulates in body tissues, vertebrae, joints and heart valves,.
For example, a dark yellow to orange color may signify the presence of bilirubin, which is indicative of liver disease and/or biliary-tract obstruction, while brown and/or black urine may be caused by the presence of melanin or homogentisic acid. Importantly, neither melanin nor homogentisic acid are detected in a routine urinalysis, therefore careful attention to the color of urine can provide an important clue to an underlying disease process.
Ochronosis results from a deficiency of homogentisic acid oxidase and leads to deposition of homogentisic acid in tissues.