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Record Information
Created at2005-11-16 15:48:42 UTC
Updated at2022-02-17 17:51:10 UTC
NP-MRD IDNP0000124
Secondary Accession NumbersNone
Natural Product Identification
Common NameCitrulline
DescriptionCitrulline, also known as Cit or δ-ureidonorvaline, belongs to the class of organic compounds known as l-alpha-amino acids. These are alpha amino acids which have the L-configuration of the alpha-carbon atom. Citrulline has the formula H2NC(O)NH(CH2)3CH(NH2)CO2H. Citrulline exists in all living species, ranging from bacteria to humans. Within humans, citrulline participates in a number of enzymatic reactions. In particular, citrulline can be biosynthesized from carbamoyl phosphate and ornithine which is catalyzed by the enzyme ornithine carbamoyltransferase. In addition, citrulline and L-aspartic acid can be converted into argininosuccinic acid through the action of the enzyme argininosuccinate synthase. In humans, citrulline is involved in the metabolic disorder called argininemia. Citrulline has also been found to be associated with several diseases such as ulcerative colitis, rheumatoid arthritis, and citrullinemia type II. Citrulline has also been linked to several inborn metabolic disorders including argininosuccinic aciduria and fumarase deficiency. Outside of the human body, citrulline is found, on average, in the highest concentration in a few different foods such as wheats, oats, and cucumbers and in a lower concentration in swiss chards, yellow wax beans, and potato. Citrulline has also been detected, but not quantified in several different foods, such as epazotes, lotus, common buckwheats, strawberry guava, and italian sweet red peppers. Citrulline is a potentially toxic compound. Proteins that normally contain citrulline residues include myelin basic protein (MBP), filaggrin, and several histone proteins, whereas other proteins, such as fibrin and vimentin are susceptible to citrullination during cell death and tissue inflammation. Citrulline is also produced as a byproduct of the enzymatic production of nitric oxide from the amino acid arginine, catalyzed by nitric oxide synthase. It is also produced from arginine as a byproduct of the reaction catalyzed by NOS family (NOS; EC1.14.13.39).
(S)-2-Amino-5-ureidopentanoic acidChEBI
2-Amino-5-ureidovaleric acidChEBI
alpha-Amino-delta-ureidovaleric acidChEBI
L-2-Amino-5-ureidovaleric acidChEBI
a-Amino-delta-ureidovaleric acidGenerator
Α-amino-δ-ureidovaleric acidGenerator
a-Amino-δ-ureidovaleric acidHMDB
(2S)-2-Amino-5-(carbamoylamino)pentanoic acidHMDB
(S)-2-Amino-5-(aminocarbonyl)aminopentanoic acidHMDB
2-Amino-5-uredovaleric acidHMDB
a-Amino-D-ureidovaleric acidHMDB
alpha-Amino-gamma-ureidovaleric acidHMDB
Amino-ureidovaleric acidHMDB
L(+)-2-Amino-5-ureidovaleric acidHMDB
L-2-Amino-5-ureido-valeric acidHMDB
Ureidovaleric acidHMDB
Chemical FormulaC6H13N3O3
Average Mass175.1857 Da
Monoisotopic Mass175.09569 Da
IUPAC Name(2S)-2-amino-5-(carbamoylamino)pentanoic acid
Traditional NameL-citrulline
CAS Registry Number372-75-8
InChI Identifier
Experimental Spectra
Spectrum TypeDescriptionDepositor EmailDepositor OrganizationDepositorDeposition DateView
1D NMR1H NMR Spectrum (1D, 700 MHz, H2O, simulated)Ahselim2022-02-17View Spectrum
1D NMR1H NMR Spectrum (1D, 700 MHz, H2O, experimental)Ahselim2022-02-17View Spectrum
1D NMR1H NMR Spectrum (1D, 500 MHz, H2O, experimental)Wishart LabWishart LabDavid Wishart2021-06-20View Spectrum
2D NMR[1H, 13C]-HSQC NMR Spectrum (2D, 600 MHz, H2O, experimental)Wishart LabWishart LabDavid Wishart2021-06-20View Spectrum
Predicted Spectra
Not Available
Chemical Shift Submissions
Spectrum TypeDescriptionDepositor EmailDepositor OrganizationDepositorDeposition DateView
1D NMR13C NMR Spectrum (1D, 400 MHz, H2O, simulated)varshavi.d26@gmail.comNot AvailableNot Available2021-07-21View Spectrum
Species of Origin
Species NameSourceReference
Allium sativumLOTUS Database
Apis ceranaLOTUS Database
Arabidopsis thalianaPlant
Cannabis sativaCannabisDB
      Not Available
Carica papaya L.Plant
Chondria armataLOTUS Database
Citrullus vulgarisPlant
Cycas revolutaLOTUS Database
Escherichia coliBacteria
Flammulina velutipesLOTUS Database
Homo sapiensLOTUS Database
Homo sapiens (Urine)Animalia
Juncus roemerianusLOTUS Database
Mus musculusLOTUS Database
Mycoplasma gallisepticumLOTUS Database
Opuntia ficus-indicaLOTUS Database
Prunus domesticaLOTUS Database
Salmonella entericaLOTUS Database
Santalum albumPlant
Sesamum indicumPlant
Synechococcus elongatusLOTUS Database
Thalassiosira pseudonanaLOTUS Database
Trypanosoma bruceiLOTUS Database
Chemical Taxonomy
Description Belongs to the class of organic compounds known as l-alpha-amino acids. These are alpha amino acids which have the L-configuration of the alpha-carbon atom.
KingdomOrganic compounds
Super ClassOrganic acids and derivatives
ClassCarboxylic acids and derivatives
Sub ClassAmino acids, peptides, and analogues
Direct ParentL-alpha-amino acids
Alternative Parents
  • L-alpha-amino acid
  • Fatty acid
  • Isourea
  • Amino acid
  • Carboximidic acid derivative
  • Carboxylic acid
  • Monocarboxylic acid or derivatives
  • Carboximidamide
  • Amine
  • Hydrocarbon derivative
  • Primary amine
  • Organooxygen compound
  • Organonitrogen compound
  • Organic oxide
  • Primary aliphatic amine
  • Organopnictogen compound
  • Imine
  • Organic oxygen compound
  • Organic nitrogen compound
  • Carbonyl group
  • Aliphatic acyclic compound
Molecular FrameworkAliphatic acyclic compounds
External Descriptors
Physical Properties
Experimental Properties
Melting Point235.5 °CNot Available
Boiling PointNot AvailableNot Available
Water Solubility212 mg/mLNot Available
LogP-3.19Sangster, J. (1993). LOGKOW- a Databank of Evaluated Octanol-Water Partition Coefficients. Sangster Research Laboratories, Montreal.
Predicted Properties
Water Solubility21.8 g/LALOGPS
pKa (Strongest Acidic)2.27ChemAxon
pKa (Strongest Basic)9.23ChemAxon
Physiological Charge0ChemAxon
Hydrogen Acceptor Count4ChemAxon
Hydrogen Donor Count4ChemAxon
Polar Surface Area118.44 ŲChemAxon
Rotatable Bond Count5ChemAxon
Refractivity41.33 m³·mol⁻¹ChemAxon
Polarizability17.35 ųChemAxon
Number of Rings0ChemAxon
Rule of FiveYesChemAxon
Ghose FilterNoChemAxon
Veber's RuleNoChemAxon
MDDR-like RuleNoChemAxon
DrugBank IDDB00155
Phenol Explorer Compound IDNot Available
FoodDB IDFDB112167
KNApSAcK IDC00001348
Chemspider ID9367
KEGG Compound IDC00327
BiGG ID34627
Wikipedia LinkCitrulline
PubChem Compound9750
PDB IDNot Available
ChEBI ID16349
Good Scents IDrw1253471
General References
  1. Sreekumar A, Poisson LM, Rajendiran TM, Khan AP, Cao Q, Yu J, Laxman B, Mehra R, Lonigro RJ, Li Y, Nyati MK, Ahsan A, Kalyana-Sundaram S, Han B, Cao X, Byun J, Omenn GS, Ghosh D, Pennathur S, Alexander DC, Berger A, Shuster JR, Wei JT, Varambally S, Beecher C, Chinnaiyan AM: Metabolomic profiles delineate potential role for sarcosine in prostate cancer progression. Nature. 2009 Feb 12;457(7231):910-4. doi: 10.1038/nature07762. [PubMed:19212411 ]
  2. Engelborghs S, Marescau B, De Deyn PP: Amino acids and biogenic amines in cerebrospinal fluid of patients with Parkinson's disease. Neurochem Res. 2003 Aug;28(8):1145-50. [PubMed:12834252 ]
  3. Hagenfeldt L, Bjerkenstedt L, Edman G, Sedvall G, Wiesel FA: Amino acids in plasma and CSF and monoamine metabolites in CSF: interrelationship in healthy subjects. J Neurochem. 1984 Mar;42(3):833-7. [PubMed:6198473 ]
  4. Cynober LA: Plasma amino acid levels with a note on membrane transport: characteristics, regulation, and metabolic significance. Nutrition. 2002 Sep;18(9):761-6. [PubMed:12297216 ]
  5. Rainesalo S, Keranen T, Palmio J, Peltola J, Oja SS, Saransaari P: Plasma and cerebrospinal fluid amino acids in epileptic patients. Neurochem Res. 2004 Jan;29(1):319-24. [PubMed:14992292 ]
  6. Le Boucher J, Charret C, Coudray-Lucas C, Giboudeau J, Cynober L: Amino acid determination in biological fluids by automated ion-exchange chromatography: performance of Hitachi L-8500A. Clin Chem. 1997 Aug;43(8 Pt 1):1421-8. [PubMed:9267323 ]
  7. Crenn P, Coudray-Lucas C, Thuillier F, Cynober L, Messing B: Postabsorptive plasma citrulline concentration is a marker of absorptive enterocyte mass and intestinal failure in humans. Gastroenterology. 2000 Dec;119(6):1496-505. [PubMed:11113071 ]
  8. Melis GC, Boelens PG, van der Sijp JR, Popovici T, De Bandt JP, Cynober L, van Leeuwen PA: The feeding route (enteral or parenteral) affects the plasma response of the dipetide Ala-Gln and the amino acids glutamine, citrulline and arginine, with the administration of Ala-Gln in preoperative patients. Br J Nutr. 2005 Jul;94(1):19-26. [PubMed:16115328 ]
  9. DeLong GR, Glick TH: Ammonia metabolism in Reye syndrome and the effect of citrulline. Ann Neurol. 1982 Jan;11(1):53-8. [PubMed:7059128 ]
  10. Jianfeng G, Weiming Z, Ning L, Fangnan L, Li T, Nan L, Jieshou L: Serum citrulline is a simple quantitative marker for small intestinal enterocytes mass and absorption function in short bowel patients. J Surg Res. 2005 Aug;127(2):177-82. [PubMed:15921697 ]
  11. Liappis N, Pohl B, Weber HP, el-Karkani H: [Free amino acids in the saliva of children with phenylketonuria]. Klin Padiatr. 1986 Jan-Feb;198(1):25-8. [PubMed:3959486 ]
  12. Fleisher LD, Harris CJ, Mitchell DA, Nadler HL: Citrullinemia: prenatal diagnosis of an affected fetus. Am J Hum Genet. 1983 Jan;35(1):85-90. [PubMed:6823975 ]
  13. Potter MA, Zeesman S, Brennan B, Kobayashi K, Gao HZ, Tabata A, Saheki T, Whelan DT: Pregnancy in a healthy woman with untreated citrullinemia. Am J Med Genet A. 2004 Aug 15;129A(1):77-82. [PubMed:15266621 ]
  14. Wheatley DN, Kilfeather R, Stitt A, Campbell E: Integrity and stability of the citrulline-arginine pathway in normal and tumour cell lines. Cancer Lett. 2005 Sep 28;227(2):141-52. [PubMed:16112417 ]
  15. Reparon-Schuijt CC, van Esch WJ, van Kooten C, Schellekens GA, de Jong BA, van Venrooij WJ, Breedveld FC, Verweij CL: Secretion of anti-citrulline-containing peptide antibody by B lymphocytes in rheumatoid arthritis. Arthritis Rheum. 2001 Jan;44(1):41-7. [PubMed:11212174 ]
  16. Maruyama H, Ogawa M, Nishio T, Kobayashi K, Saheki T, Sunohara N: Citrullinemia type II in a 64-year-old man with fluctuating serum citrulline levels. J Neurol Sci. 2001 Jan 1;182(2):167-70. [PubMed:11137523 ]
  17. McLaurin J, Moscarello MA: The preparation of antibodies reactive against citrulline-containing charge isomers of myelin basic protein but not against the arginine-containing charge isomers. Anal Biochem. 1990 Dec;191(2):272-7. [PubMed:1707596 ]
  18. Facchinetti F, Longo M, Piccinini F, Neri I, Volpe A: L-arginine infusion reduces blood pressure in preeclamptic women through nitric oxide release. J Soc Gynecol Investig. 1999 Jul-Aug;6(4):202-7. [PubMed:10486782 ]
  19. Origuchi Y, Ushijima T, Sakaguchi M, Akaboshi I, Matsuda I: Citrullinemia presenting as uncontrollable epilepsy. Brain Dev. 1984;6(3):328-31. [PubMed:6486381 ]
  20. Booth FA, Haworth JC, Dilling LA, Perry TL, Greenberg CR, Seargeant LE, Penn AM, Rhead WJ: Mitochondrial encephalomyopathy with associated aminoacidopathy in a male sibship. J Pediatr. 1989 Jul;115(1):81-8. [PubMed:2738799 ]
  21. Ciesielski O, Biesiekierska M, Panthu B, Soszynski M, Pirola L, Balcerczyk A: Citrullination in the pathology of inflammatory and autoimmune disorders: recent advances and future perspectives. Cell Mol Life Sci. 2022 Jan 25;79(2):94. doi: 10.1007/s00018-022-04126-3. [PubMed:35079870 ]