Maleylacetic acid is a chemical compound produced in the biodegradation of catechin by Bradyrhizobium japonicum.
In Moraxella species, the compound is a product of the metabolism of hydroquinone, with the final step being from oxidation of 4-hydroxymuconic semialdehyde:
The compound is reduced to 3-oxoadipic acid by the enzyme maleylacetate reductase in Trichosporon cutaneum: