Homogentisic acid

Structural formula
General
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
Features
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] Attention 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 1.13.11.5):

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