Orotic acid

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Orotic acid
Orotic acid.svg
Systematic (IUPAC) name
1,2,3,6-tetrahydro-2,6-dioxo-4-pyrimidinecarboxylic acid
Clinical data
AHFS/Drugs.com International Drug Names
Legal status
CAS number 65-86-1 YesY
ATC code None
PubChem CID 967
DrugBank DB02262
ChemSpider 942 N
UNII 61H4T033E5 N
KEGG C00295 N
Chemical data
Formula C5H4N2O4 
Mol. mass 156.10 g/mol
 N (what is this?)  (verify)

Orotic acid is a heterocyclic compound and an acid; it is also known as pyrimidinecarboxylic acid. Historically it was believed to be part of the Vitamin B complex and was called vitamin B13, but it is now known that it is not a vitamin.

The compound is manufactured in the body via a mitochondrial enzyme, dihydroorotate dehydrogenase.[1] or a cytoplasmic enzyme of pyrimidine synthesis pathway. It is sometimes used as a mineral carrier in some dietary supplements (to increase their bioavailability), most commonly for lithium orotate.

Synthesis of orotate[edit]

Dihydroorotate is synthesized to orotic acid by the enzyme dihydroorate dehydrogenase, where it later combines with phosphoribosyl pyrophosphate (PRPP) to form orotidine-5'-monophosphate (OMP). A distinguishing characteristic of pyrimidine synthesis is that the pyrimidine ring is fully synthesized before being attached to the ribose sugar, whereas purine synthesis happens by building the base directly on the sugar.[2]

Orotic acid diseases[edit]

A buildup of orotic acid can lead to orotic aciduria and acidemia. It may be a symptom of an increased ammonia load due to a metabolic disorder, such as a urea cycle disorder.

In ornithine transcarbamoylase deficiency, an X-linked inherited and the most common urea cycle disorder, excess carbamoyl phosphate is converted into orotic acid. This leads to an increased serum ammonia level, increased serum and urinary orotic acid levels and a decreased serum BUN level. This also leads to an increased urinary orotic acid excretion, because the orotic acid is not being properly utilized and must be eliminated. The hyperammonemia depletes alpha-ketoglutarate leading to the inhibition of the tricarboxylic acid cycle (TCA) decreasing ATP production.

Orotic acid can be mutagenic (causes mutations) in mammalian somatic cells.[dubious ] It is also mutagenic for bacteria and or yeast.

See also[edit]


  1. ^ Rawls J. et al. (2000) Requirements for the mitochondrial import and localization of dihydroorotate dehydrogenase. Eur. J. Biochem.
  2. ^ Lippincott. Biochemistry 4th Edition. 2008

External links[edit]