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L-Dihydroorotic acid


L-Hydroorotic acid, Dihydro-L-orotic acid, 2,6-Dioxohexahydro-4-pyrimidinecarboxylic acid
Empirical Formula (Hill Notation):
CAS Number:
Molecular Weight:
MDL number:
PubChem Substance ID:

Quality Level






254-255 °C (dec.) (lit.)

SMILES string




InChI key


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L-Dihydroorotic acid has been used as a substrate in dihydroorotate dehydrogenase (DHODH) assay.


500 mg in poly bottle
1, 5 g in poly bottle

Biochem/physiol Actions

L-Dihydroorotic acid (DHO) serves as a substrate for dihydroorotate dehydrogenase (DHODH), an enzyme in the de novo synthesis of pyrimidine. Inhibition of DHOH by its inhibitors causes a large accumulation of upstream metabolite DHO and a reduction in the uridine levels. Therefore, DHO and uridine can be used as biomarkers for pyrimidine synthesis for the clinical development of DHOH inhibitors.

Other Notes

Tandem Mass Spectrometry data independently generated by Scripps Center for Metabolomics is available to view or download in PDF. D7128.pdf Tested metabolites are featured on Scripps Center for Metabolomics METLIN Metabolite Database. To learn more, visit


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Hazard Statements

Precautionary Statements

Hazard Classifications

Eye Irrit. 2 - Skin Irrit. 2 - STOT SE 3

Target Organs

Respiratory system

Storage Class Code

11 - Combustible Solids



Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

Personal Protective Equipment

dust mask type N95 (US), Eyeshields, Gloves

Certificate of Analysis

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Certificate of Origin

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Feng Yin et al.
Journal of pharmaceutical and biomedical analysis, 192, 113669-113669 (2020-10-30)
Uridine and L-dihydroorotate (DHO) are important intermediates of de novo as well as salvage pathways for the biosynthesis of pyrimidines, which are the building blocks of nucleic acids - DNA and RNA. These metabolites are known to be significant biomarkers
Yihan Wu et al.
Cell chemical biology, 24(12), 1437-1444 (2017-10-17)
Microbial natural products are genetically encoded by dedicated biosynthetic gene clusters (BGCs). A given BGC usually produces a family of related compounds that share a core but contain variable substituents. Though common, the reasons underlying this divergent biosynthesis are in
Michelle L Zaharik et al.
Microbiology (Reading, England), 153(Pt 8), 2472-2482 (2007-07-31)
Mutants capable of utilizing the pyrimidine biosynthetic intermediates carbamoylaspartate and dihydroorotate for growth were derived from pyrimidine auxotrophs of Salmonella enterica serovar Typhimurium LT2. The gain-of-function phenotypes both resulted from mutations in a single gene, yhiT, the third gene of
O Björnberg et al.
Archives of biochemistry and biophysics, 391(2), 286-294 (2001-07-05)
The flavoprotein dihydroorotate dehydrogenase (DHOD) catalyzes the oxidation of dihydroorotate to orotate. Dihydrooxonate is an analogue of dihydroorotate in which the C5 carbon is substituted by a nitrogen atom. We have investigated dihydrooxonate as a substrate of three DHODs, each
Mihwa Lee et al.
Journal of molecular biology, 348(3), 523-533 (2005-04-14)
Escherichia coli dihydroorotase has been crystallized in the presence of the product, L-dihydroorotate (L-DHO), and the structure refined at 1.9A resolution. The structure confirms that previously reported (PDB entry 1J79), crystallized in the presence of the substrate N-carbamyl-D,L-aspartate (D, L-CA-asp)

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