Homogentisic acid explained

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.

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.

4-Hydroxyphenylpyruvate (produced by transamination of tyrosine) is acted upon by the enzyme 4-hydroxyphenylpyruvate dioxygenase to yield homogentisate.[5] If active and present, the enzyme homogentisate 1,2-dioxygenase further degrades homogentisic acid to yield 4-maleylacetoacetic acid.[6]

Notes and References

  1. Homogentisic Acid: A Phenolic Acid as a Marker of Strawberry-Tree (Arbutus unedo) Honey . Paolo Cabras . Alberto Angioni . Carlo Tuberoso . Ignazio Floris . Fabiano Reniero . Claude Guillou . Stefano Ghelli . J. Agric. Food Chem. . 1999 . 47 . 10 . 4064–4067 . 10.1021/jf990141o. 10552766 .
  2. Brown pigmentation of Xanthomonas campestris pv. phaseoli associated with homogentisic acid . Goodwin PH, Sopher CR . Canadian Journal of Microbiology . 40 . 1 . 28–34 . 1994 . 10.1139/m94-005 . 25 February 2011 . 21 July 2011 . https://web.archive.org/web/20110721001238/http://cat.inist.fr/?aModele=afficheN&cpsidt=3978055 . dead.
  3. Brown Pigments Produced by Yarrowia lipolytica Result from Extracellular Accumulation of Homogentisic Acid . Alexandra Carreira . Luísa M. Ferreira . Virgílio Loureiro . Appl Environ Microbiol . 2001 . 67 . 8 . 3463–3468 . 10.1128/AEM.67.8.3463-3468.2001. 11472920 . 93044 . 10.1.1.319.523 .
  4. Phornphutkul C, Introne WJ, Perry MB, etal . Natural history of alkaptonuria . New England Journal of Medicine . 347 . 26 . 2111–21 . 2002 . 12501223 . 10.1056/NEJMoa021736. free .
  5. Lindstedt . Sven . Odelhog . Birgit . Rundgren . Marianne . Purification and Some Properties of 4-Hydroxyphenylpyruvate Dioxygenase from Pseudomonas sp. P.J. 814 . Biochemistry . 1977 . 16 . 15 . 3369–3377 . 10.1021/bi00634a013.
  6. Knox WE, LeMay-Knox M . The oxidation in liver of l-tyrosine to acetoacetate through p-hydroxyphenylpyruvate and homogentisic acid . The Biochemical Journal . 49 . 5 . 686–93 . October 1951 . 14886367 . 1197578 . 10.1042/bj0490686 .

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