Homogentisic acid

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Structural formula
Strukturformel von Homogentisinsäure
Name Homogentisic acid
Other names

2,5-Dihydroxyphenylacetic acid

Sum formula C8H8O4
Brief description

beige solid[1]

External identifiers/databases
CAS number 451-13-8
EC number 207-192-7
ECHA InfoCard 100.006.540
PubChem 780
ChemSpider 759
DrugBank DB08327
Wikidata Q416054
Molar mass 168.15 g-mol-1
State of aggregation

synced and corrected by elderman — – for —

Melting point

152-154 °C (monohydrate)[2]

Safety instructions
GHS Hazardous Substance Labeling [1]

07 – Achtung


H and P phrases H 315– ‐319– ‐335
P 261– ‐305+351+338 [1]
SI units are used wherever possible and customary. Unless otherwise stated, the data given are valid for standard conditions.

Homogentisic acid is an intermediate product of the degradation of the amino acids phenylalanine and tyrosine and is present as an anion(homogentisate) at physiological pH values. It is converted into 4-maleylacetoacetic acid by the enzyme homogentisate dioxygenase (EC

Umwandlung von Homogenisate zu 4-Maleylacetoacetat. Dies wird durch die Homogentisat-1,2-Dioxygenase unter Verbrauch von Sauerstoff katalysiert.

Subsequently, acetoacetic acid and fumaric acid are formed from this, which can be fed into the citrate cycle.[2]

In alkaptonuria, a metabolic disease, the enzyme is absent or not present in sufficient amounts. “Alkapton” is the oxidized, black-brown form of the homogentisate.

See also

  • Metabolic disorder

Individual references

  1. a b c Data sheet Homogentisic acid at Sigma-Aldrich, retrieved April 4, 2011 (PDF). Template:Sigma-Aldrich/call not specified
  2. a b Entry for Homogentisic acid. In: Römpp Online. Georg Thieme Verlag, retrieved 16 June 2014