Homogentisic acid

Homogentisic acid (2,5-dihydroxyphenylacetic acid) is a phenolic acid usually found in Arbutus unedo (strawberry-tree) honey.[1] It is also present in the bacterial plant pathogen Xanthomonas campestris pv. phaseoli[2] as well as in the yeast Yarrowia lipolytica[3] where it is associated with the production of brown pigments. It is oxidatively dimerised to form hipposudoric acid, one of the main constituents of the 'blood sweat' of hippopotamuses.

Homogentisic acid
Names
IUPAC name
(2,5-Dihydroxyphenyl)acetic acid
Other names
Melanic acid
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
DrugBank
ECHA InfoCard 100.006.540
KEGG
MeSH Homogentisic+acid
UNII
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 their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

It is less commonly known as melanic acid, the name chosen by William Prout.

Human pathology

Accumulation of excess homogentisic acid and its oxide, named alkapton, is a result of the failure of the enzyme homogentisic acid 1,2-dioxygenase (typically due to a mutation) in the degradative pathway of tyrosine, consequently associated with alkaptonuria.[4]

Intermediate

It is an intermediate in the catabolism of aromatic amino acids such as phenylalanine and tyrosine.

p-Hydroxyphenyl pyruvate (produced by transamination of tyrosine) is acted upon by the enzyme p-hydroxyphenyl pyruvate oxidase to yield homogentisate. It is then degraded by the enzyme homogentisate oxidase to give maleyl-acetoacetate.

References
  1. Paolo Cabras; Alberto Angioni; Carlo Tuberoso; Ignazio Floris; Fabiano Reniero; Claude Guillou; Stefano Ghelli (1999). "Homogentisic Acid: A Phenolic Acid as a Marker of Strawberry-Tree (Arbutus unedo) Honey". J. Agric. Food Chem. 47 (10): 4064–4067. doi:10.1021/jf990141o. PMID 10552766.
  2. Goodwin PH, Sopher CR (1994). "Brown pigmentation of Xanthomonas campestris pv. phaseoli associated with homogentisic acid". Canadian Journal of Microbiology. 40 (1): 28–34. doi:10.1139/m94-005.
  3. Alexandra Carreira; Luísa M. Ferreira; Virgílio Loureiro (2001). "Brown Pigments Produced by Yarrowia lipolytica Result from Extracellular Accumulation of Homogentisic Acid". Appl Environ Microbiol. 67 (8): 3463–3468. CiteSeerX 10.1.1.319.523. doi:10.1128/AEM.67.8.3463-3468.2001. PMC 93044. PMID 11472920.
  4. Phornphutkul C, Introne WJ, Perry MB, et al. (2002). "Natural history of alkaptonuria". New England Journal of Medicine. 347 (26): 2111–21. doi:10.1056/NEJMoa021736. PMID 12501223.

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