Carminic acid (C22H20O13) is a red glucosidal hydroxyanthapurin that occurs naturally in some scale insects, such as the cochineal and the Polish cochineal. The insects produce the acid as a feeding deterrent. Carminic acid is the colouring agent in carmine. Synonyms are C.I. 75470 and C.I. Natural Red 4.
The chemical structure of carminic acid consists of a core anthraquinone structure linked to a glucose sugar unit. Carminic acid was first synthesized by organic chemists in 1991.