Orotic Acid is an organic acid which serves as an intermediate in nucleotide synthesis and is linked to arginine metabolism as a urea cycle marker for nitrogen balance.
It is formed from aspartic acid and carbamoyl phosphate. Carbamoyl phosphate plays an important role in the body because it brings nitrogen into the urea cycle for detoxification and disposal. Carbamoyl phosphate enters the urea cycle to react with ornithine to form citrulline. When ammonia levels significantly increase or the liver’s capacity for detoxifying ammonia into urea decreases, carbamoyl phosphate leaves the mitochondria and instead enters the pyrimidine pathway. This stimulates orotic acid biosynthesis and subsequent urinary excretion. Orotic acid can also be found in the diet. The richest dietary sources include cow’s milk and dairy products.
Most urinary orotic acid is synthesized in the body as an intermediate in the nucleotide synthesis. Although it is also linked with abnormalities in arginine metabolism as a urea cycle marker for nitrogen balance, orotic acid plays no direct role in the urea cycle, yet is increased in urea cycle disorders. Hyperammonemia is characteristic of all urea cycle disorders; orotic acid is only elevated in a few.
References:
- Brosnan ME, Brosnan JT. Orotic Acid Excretion and Arginine Metabolism. J Nutr. 2007;137(6):1656S-1661S.
- Nyc JF, Mitchell HK. Synthesis of Orotic Acid from Aspartic Acid. J Am Chem Soc. 1947;69(6):1382-1384.
- Visek WJ. Nitrogen-stimulated orotic acid synthesis and nucleotide imbalance. Cancer Res. 1992;52(7 Suppl):2082s-2084s.
- Löffler M, Carrey EA, Zameitat E. Orotate (orotic acid): An essential and versatile molecule. Nucleosid Nucleot Nucl Acids. 2016;35(10- 12):566-577.
- Visek WJ, Shoemaker JD. Orotic acid, arginine, and hepatotoxicity. J Am Coll Nutr. 1986;5(2):153-166.
- Salerno C, Crifo C. Diagnostic value of urinary orotic acid levels: applicable separation methods. J Chromatog B, AnalTechnol Biomed Life Sci. 2002;781(1-2):57-71.
- Choi Y-J, Yoon Y, Lee K-Y, et al. Orotic Acid Induces Hypertension Associated with Impaired Endothelial Nitric Oxide Synthesis. Toxicol Sci. 2015;144(2):307-317.
- Haggard ME, Lockhart LH. Megaloblastic anemia and orotic aciduria. A hereditary disorder of pyrimidine metabolism responsive to uridine. Am J Dis Children (1960). 1967;113(6):733- 740
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