Homogentisic acid is a phenolic acid

Phenolic acid

Phenolic acids are a type of organic compounds. Included in that class are substances containing a phenolic ring and an organic carboxylic acid function ....

 found in Arbutus unedo (strawberry-tree) honey. It is also present in the bacterial plant pathogen Xanthomonas campestris pv. phaseoli as well as in the yeast Yarrowia lipolytica where it is associated with the production of brown pigments.

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

William Prout

William Prout FRS was an English chemist, physician, and natural theologian. He is remembered today mainly for what is called Prout's hypothesis.-Biography:...

.

Human pathology

Accumulation of excess homogentisic acid is a result of the failure of the enzyme homogentisic acid 1,2-dioxygenase (typically due to a mutation) and is associated with alkaptonuria

Alkaptonuria

Alkaptonuria is a rare inherited genetic disorder of phenylalanine and tyrosine metabolism. This is an autosomal recessive condition that is due to a defect in the enzyme homogentisate 1,2-dioxygenase , which participates in the degradation of tyrosine...

.

Intermediate

It is an intermediate in the metabolism of aromatic amino acids such as phenylalanine

Phenylalanine

Phenylalanine is an α-amino acid with the formula C6H5CH2CHCOOH. This essential amino acid is classified as nonpolar because of the hydrophobic nature of the benzyl side chain. L-Phenylalanine is an electrically neutral amino acid, one of the twenty common amino acids used to biochemically form...

 and tyrosine

Tyrosine

Tyrosine or 4-hydroxyphenylalanine, is one of the 22 amino acids that are used by cells to synthesize proteins. Its codons are UAC and UAU. It is a non-essential amino acid with a polar side group...

.