(also 1,2,3,6-tetrahydro-2,6-dioxo-4-pyrimidine-carboxylic acid or uracil-6-carboxylic acid), colorless crystals that are poorly soluble in water and organic solvents; melting point, 323°-345°C (with decomposition). Orotic acid was first extracted from cow’s milk in 1905 and later discovered in the milk of other animals and humans. Concentrated mainly in yeasts and in the liver, it is synthesized from aspartic acid and takes part in the biosynthesis of pyrimidine nucleotides, including uridine-5’-monophosphate and cytidine monophosphates. It also stimulates growth in plants and animals. The potassium salt of orotic acid is used in medicine to treat disorders in protein metabolism.