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| Names | |
|---|---|
| Preferred IUPAC name (2,5-Dihydroxyphenyl)acetic acid | |
| Other names Melanic acid | |
| Identifiers | |
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3D model (JSmol) | |
| ChEBI | |
| ChemSpider |
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| DrugBank |
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| ECHA InfoCard | 100.006.540 |
| KEGG |
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| MeSH | Homogentisic+acid |
| UNII | |
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| Properties | |
| C8H8O4 | |
| Molar mass | 168.148 g·mol−1 |
| Melting point | 150 to 152 °C (302 to 306 °F; 423 to 425 K) |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Homogentisic acid (2,5-dihydroxyphenylacetic acid) is aphenolic acid usually found inArbutus unedo (strawberry-tree) honey.[1] It is also present in the bacterial plant pathogenXanthomonas campestris pv.phaseoli[2] as well as in the yeastYarrowia lipolytica[3] where it is associated with the production of brown pigments. It is oxidativelydimerised to formhipposudoric acid, one of the main constituents of the 'blood sweat' ofhippopotamuses.
It is less commonly known asmelanic acid, the name chosen byWilliam Prout.
Accumulation of excess homogentisic acid and its oxide, namedalkapton, is a result of the failure of the enzymehomogentisic acid 1,2-dioxygenase (typically due to a mutation) in the degradative pathway oftyrosine, consequently associated withalkaptonuria.[4]
It is anintermediate in thecatabolism of aromatic amino acids such asphenylalanine andtyrosine.
4-Hydroxyphenylpyruvate (produced bytransamination of tyrosine) is acted upon by the enzyme4-hydroxyphenylpyruvate dioxygenase to yield homogentisate.[5] If active and present, the enzymehomogentisate 1,2-dioxygenase further degrades homogentisic acid to yield4-maleylacetoacetic acid.[6]
