Hypogeic acid is a monounsaturated fatty acid of the omega-9 group. Its chemical formula is C16H30O2, and its delta notation is 16:1Δ7c. The acid is composed of 16 carbon atoms, with one double bond in position 7=8 in cis-configuration. The compound has the structural formula CH3-(CH2)7-CH=CH-(CH2)5-COOH.

Hypogeic acid is found in Monascus purpureus and Arachis hypogaea. The compound can also be isolated from autotrophic bacterial cultures associated with the accumulation of sulfate in biofilters.

Discovery

The acid was initially found by Gössmann and Scheven in 1854–1855, together with palmitic and arachidic acids in earth-nut oil that was used as a substitute for olive oil.

Physical properties

Hypogeic acid is soluble in alcohol and forms colorless needle-like crystals.