You are using an unsupported browser. Please upgrade your browser to a newer version to get the best experience on Human Metabolome Database.
Record Information
Creation Date2005-11-16 15:48:42 UTC
Update Date2017-03-02 21:26:40 UTC
Secondary Accession NumbersNone
Metabolite Identification
Common NamePyridoxal
DescriptionThe 4-carboxyaldehyde form of vitamin B6 which is converted to pyridoxal phosphate which is a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid.
Chemical FormulaC8H9NO3
Average Molecular Weight167.162
Monoisotopic Molecular Weight167.058243159
IUPAC Name3-hydroxy-5-(hydroxymethyl)-2-methylpyridine-4-carbaldehyde
Traditional Namepyridoxal
CAS Registry Number66-72-8
InChI Identifier
Chemical Taxonomy
DescriptionThis compound belongs to the class of chemical entities known as pyridoxals and derivatives. These are compounds containing a pyridoxal moiety, which consists of a pyridine ring substituted at positions 2,3,4, and 5 by a methyl group, a hydroxyl group, a carbaldehyde group, and a hydroxymethyl group, respectively.
KingdomChemical entities
Super ClassOrganic compounds
ClassOrganoheterocyclic compounds
Sub ClassPyridines and derivatives
Direct ParentPyridoxals and derivatives
Alternative Parents
  • Pyridoxal
  • Aryl-aldehyde
  • Hydroxypyridine
  • Methylpyridine
  • Vinylogous acid
  • Heteroaromatic compound
  • Azacycle
  • Hydrocarbon derivative
  • Aldehyde
  • Alcohol
  • Organic oxygen compound
  • Aromatic alcohol
  • Organic nitrogen compound
  • Primary alcohol
  • Organooxygen compound
  • Organonitrogen compound
  • Organopnictogen compound
  • Organic oxide
  • Aromatic heteromonocyclic compound
Molecular FrameworkAromatic heteromonocyclic compounds
External Descriptors
StatusDetected and Quantified
  • Endogenous
  • Component of Vitamin B6 metabolism
ApplicationNot Available
Cellular locations
  • Cytoplasm
  • Extracellular
Physical Properties
Experimental Properties
Melting Point165 °CNot Available
Boiling PointNot AvailableNot Available
Water Solubility500.0 mg/mLNot Available
LogPNot AvailableNot Available
Predicted Properties
Water Solubility11.7 mg/mLALOGPS
pKa (Strongest Acidic)7.97ChemAxon
pKa (Strongest Basic)4.11ChemAxon
Physiological Charge0ChemAxon
Hydrogen Acceptor Count4ChemAxon
Hydrogen Donor Count2ChemAxon
Polar Surface Area70.42 Å2ChemAxon
Rotatable Bond Count2ChemAxon
Refractivity43.87 m3·mol-1ChemAxon
Polarizability16.28 Å3ChemAxon
Number of Rings1ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleYesChemAxon
Spectrum TypeDescriptionSplash Key
GC-MSGC-MS Spectrum - GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies)splash10-00di-2690000000-5d018202be238b10582aView in MoNA
GC-MSGC-MS Spectrum - GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies)splash10-0aou-3974000000-8c963fdc714896ad343aView in MoNA
GC-MSGC-MS Spectrum - GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies)splash10-001j-0590000000-ed8a55680a0c9fa9cbafView in MoNA
GC-MSGC-MS Spectrum - GC-MS (1 MEOX; 2 TMS)splash10-0a4i-5695000000-bd3bb22a5dd4a600cb6cView in MoNA
GC-MSGC-MS Spectrum - GC-MS (1 MEOX; 2 TMS)splash10-0aor-5895000000-e55e01ca30d17d2a8a72View in MoNA
Predicted GC-MSPredicted GC-MS Spectrum - GC-MSNot Available
LC-MS/MSLC-MS/MS Spectrum - Quattro_QQQ 10V, Positive (Annotated)splash10-0002-0900000000-4ce3f52baa36006ef4b2View in MoNA
LC-MS/MSLC-MS/MS Spectrum - Quattro_QQQ 25V, Positive (Annotated)splash10-00kg-9500000000-658a96f6cda4a96de045View in MoNA
LC-MS/MSLC-MS/MS Spectrum - Quattro_QQQ 40V, Positive (Annotated)splash10-0gbc-9000000000-233fc8ab067b0dcd1f14View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ (API3000, Applied Biosystems) 10V, Negativesplash10-014i-0900000000-c49b207cafcf1c21302dView in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ (API3000, Applied Biosystems) 20V, Negativesplash10-000i-0900000000-cad83f5f123a879fa0bbView in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ (API3000, Applied Biosystems) 30V, Negativesplash10-0a4i-0900000000-4f12feae0e11a6d9016bView in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ (API3000, Applied Biosystems) 40V, Negativesplash10-0a4i-2900000000-56fcdbb9b4363c84d2d0View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ (API3000, Applied Biosystems) 50V, Negativesplash10-056r-9400000000-9700c9585f6c540bf007View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ (API3000, Applied Biosystems) 10V, Positivesplash10-0gb9-0900000000-e646a99b0c1521d1c8ddView in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ (API3000, Applied Biosystems) 20V, Positivesplash10-0udi-0900000000-8fce1a7d8ceb3fced3edView in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ (API3000, Applied Biosystems) 30V, Positivesplash10-0udl-6900000000-e2fc0eaa17e57d0a2556View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ (API3000, Applied Biosystems) 40V, Positivesplash10-00kf-9200000000-0bda29931f8b6f2fcc77View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ (API3000, Applied Biosystems) 50V, Positivesplash10-014l-9000000000-469c127d1aef4f8a51d7View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QTOF (UPLC Q-Tof Premier, Waters) , Positivesplash10-0udi-2900000000-63ebef5a0818d6a1ccb8View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QTOF (UPLC Q-Tof Premier, Waters) , Negativesplash10-05n0-0900000000-f468a00d88bedc116485View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ , negativesplash10-000i-0900000000-bf0686eb8e3c28c30e85View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ , negativesplash10-0a4i-0900000000-686848e0f222273e5089View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ , negativesplash10-0a4i-2900000000-99577e7f4a39e47c5c42View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ , positivesplash10-0udi-0900000000-efa3bb6939a773839fa4View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Positivesplash10-0uxr-0900000000-7f4ef736d1a810b2e8abView in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Positivesplash10-0udi-0900000000-9c4ead9423b52a47b2feView in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Positivesplash10-0udi-9500000000-aa6a11948622748c8469View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Negativesplash10-014i-0900000000-dd6386614990770eaae5View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Negativesplash10-000i-0900000000-e9de9bab2598f0316525View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Negativesplash10-0abc-9300000000-f4bc767c42577b6a1d5fView in MoNA
1D NMR1H NMR SpectrumNot Available
1D NMR1H NMR SpectrumNot Available
1D NMR13C NMR SpectrumNot Available
2D NMR[1H,13C] 2D NMR SpectrumNot Available
Biological Properties
Cellular Locations
  • Cytoplasm
  • Extracellular
Biofluid Locations
  • Blood
Tissue Location
  • Erythrocyte
  • Fibroblasts
  • Kidney
  • Placenta
2-Methyl-3-Hydroxybutryl CoA Dehydrogenase DeficiencySMP00137Not Available
3-Hydroxy-3-Methylglutaryl-CoA Lyase DeficiencySMP00138Not Available
3-hydroxyisobutyric acid dehydrogenase deficiencySMP00521Not Available
3-hydroxyisobutyric aciduriaSMP00522Not Available
3-Methylcrotonyl Coa Carboxylase Deficiency Type ISMP00237Not Available
3-Methylglutaconic Aciduria Type ISMP00139Not Available
3-Methylglutaconic Aciduria Type IIISMP00140Not Available
3-Methylglutaconic Aciduria Type IVSMP00141Not Available
Beta-Ketothiolase DeficiencySMP00173Not Available
HypophosphatasiaSMP00503Not Available
Isobutyryl-coa dehydrogenase deficiencySMP00523Not Available
Isovaleric acidemiaSMP00524Not Available
Isovaleric AciduriaSMP00238Not Available
Maple Syrup Urine DiseaseSMP00199Not Available
Methylmalonate Semialdehyde Dehydrogenase DeficiencySMP00384Not Available
Methylmalonic AciduriaSMP00200Not Available
Propionic AcidemiaSMP00236Not Available
Valine, Leucine and Isoleucine DegradationSMP00032map00280
Vitamin B6 MetabolismSMP00017map00750
Normal Concentrations
BloodDetected and Quantified0.251 +/- 0.051 uMAdult (>18 years old)BothNormal
    • Geigy Scientific ...
Abnormal Concentrations
BloodDetected and Quantified0.036 +/- 0.031 uMAdult (>18 years old)BothSickle cell disease-SS (SCD-SS) details
Associated Disorders and Diseases
Disease References
Sickle cell anemia
  1. Nelson MC, Zemel BS, Kawchak DA, Barden EM, Frongillo EA Jr, Coburn SP, Ohene-Frempong K, Stallings VA: Vitamin B6 status of children with sickle cell disease. J Pediatr Hematol Oncol. 2002 Aug-Sep;24(6):463-9. [PubMed:12218594 ]
Associated OMIM IDs
DrugBank IDDB00147
DrugBank Metabolite IDNot Available
Phenol Explorer Compound IDNot Available
Phenol Explorer Metabolite IDNot Available
FoodDB IDFDB011169
KNApSAcK IDC00007509
Chemspider ID1021
KEGG Compound IDC00250
BiGG ID34393
Wikipedia LinkPyridoxal
NuGOwiki LinkHMDB01545
Metagene LinkHMDB01545
PubChem Compound1050
ChEBI ID17310
Synthesis ReferenceFujimoto, Yasuo. Pyridoxal. Jpn. Tokkyo Koho (1971), 2 pp.
Material Safety Data Sheet (MSDS)Download (PDF)
General References
  1. Rajamohan F, Nelms L, Joslin DL, Lu B, Reagan WJ, Lawton M: cDNA cloning, expression, purification, distribution, and characterization of biologically active canine alanine aminotransferase-1. Protein Expr Purif. 2006 Jul;48(1):81-9. Epub 2006 Jan 30. [PubMed:16495081 ]
  2. Huang YC, Lan PH, Cheng CH, Lee BJ, Kan MN: Vitamin B6 intakes and status of mechanically ventilated critically ill patients in Taiwan. Eur J Clin Nutr. 2002 May;56(5):387-92. [PubMed:12001008 ]
  3. Fonda ML: Vitamin B6 metabolism and binding to proteins in the blood of alcoholic and nonalcoholic men. Alcohol Clin Exp Res. 1993 Dec;17(6):1171-8. [PubMed:8116826 ]
  4. el-Habet AE, el-Sewedy SM, el-Sharaky A, Gaafar NK, Abdel-Rafee A, Hamoud F: Biochemical studies on bilharzial and nonbilharzial hyperoxaluria: effect of pyridoxine and allopurinol treatment. Biochem Med Metab Biol. 1987 Aug;38(1):1-8. [PubMed:3663392 ]
  5. Mehansho H, Henderson LM: Transport and accumulation of pyridoxine and pyridoxal by erythrocytes. J Biol Chem. 1980 Dec 25;255(24):11901-7. [PubMed:7440576 ]
  6. Kark JA, Bongiovanni R, Hicks CU, Tarassoff PG, Hannah JS, Yoshida GY: Modification of intracellular hemoglobin with pyridoxal and pyridoxal 5'-phosphate. Blood Cells. 1982;8(2):299-314. [PubMed:7159754 ]
  7. Bosse TR, Donald EA: The vitamin B6 requirement in oral contraceptive users. I. Assessment by pyridoxal level and transferase activity in erythrocytes. Am J Clin Nutr. 1979 May;32(5):1015-23. [PubMed:433818 ]
  8. Linares P, Luque de Castro MD, Valcarcel M: Simultaneous determination of pyridoxal and pyridoxal 5-phosphate in human serum by flow injection analysis. Anal Chem. 1985 Sep;57(11):2101-6. [PubMed:4051187 ]
  9. Schenker S, Johnson RF, Mahuren JD, Henderson GI, Coburn SP: Human placental vitamin B6 (pyridoxal) transport: normal characteristics and effects of ethanol. Am J Physiol. 1992 Jun;262(6 Pt 2):R966-74. [PubMed:1621875 ]
  10. Brenner A, Wapnir RA: A pyridoxine-dependent behavioral disorder unmasked by isoniazid. Am J Dis Child. 1978 Aug;132(8):773-6. [PubMed:150790 ]
  11. Kark JA, Tarassoff PG, Bongiovanni R: Pyridoxal phosphate as an antisickling agent in vitro. J Clin Invest. 1983 May;71(5):1224-9. [PubMed:6853710 ]
  12. Yiakouvaki A, Savovic J, Al-Qenaei A, Dowden J, Pourzand C: Caged-iron chelators a novel approach towards protecting skin cells against UVA-induced necrotic cell death. J Invest Dermatol. 2006 Oct;126(10):2287-95. Epub 2006 May 18. [PubMed:16710308 ]


General function:
Involved in oxidoreductase activity
Specific function:
Not Available
Gene Name:
Uniprot ID:
Molecular weight:
Pyridoxal + Oxygen + Water → 4-Pyridoxic acid + Hydrogen peroxidedetails
General function:
Involved in pyridoxamine-phosphate oxidase activity
Specific function:
Catalyzes the oxidation of either pyridoxine 5'-phosphate (PNP) or pyridoxamine 5'-phosphate (PMP) into pyridoxal 5'-phosphate (PLP).
Gene Name:
Uniprot ID:
Molecular weight:
Pyridoxamine + Water + Oxygen → Pyridoxal + Ammonia + Hydrogen peroxidedetails
Pyridoxine + Oxygen → Pyridoxal + Hydrogen peroxidedetails
General function:
Involved in lyase activity
Specific function:
The glycine cleavage system catalyzes the degradation of glycine. The P protein binds the alpha-amino group of glycine through its pyridoxal phosphate cofactor; CO(2) is released and the remaining methylamine moiety is then transferred to the lipoamide cofactor of the H protein.
Gene Name:
Uniprot ID:
Molecular weight:
General function:
Involved in pyridoxal kinase activity
Specific function:
Required for synthesis of pyridoxal-5-phosphate from vitamin B6.
Gene Name:
Uniprot ID:
Molecular weight:
Adenosine triphosphate + Pyridoxal → ADP + Pyridoxal 5'-phosphatedetails
  1. Tang L, Li MH, Cao P, Wang F, Chang WR, Bach S, Reinhardt J, Ferandin Y, Galons H, Wan Y, Gray N, Meijer L, Jiang T, Liang DC: Crystal structure of pyridoxal kinase in complex with roscovitine and derivatives. J Biol Chem. 2005 Sep 2;280(35):31220-9. Epub 2005 Jun 28. [PubMed:15985434 ]
  2. Adams JB, George F, Audhya T: Abnormally high plasma levels of vitamin B6 in children with autism not taking supplements compared to controls not taking supplements. J Altern Complement Med. 2006 Jan-Feb;12(1):59-63. [PubMed:16494569 ]
  3. Newman JA, Das SK, Sedelnikova SE, Rice DW: The crystal structure of an ADP complex of Bacillus subtilis pyridoxal kinase provides evidence for the parallel emergence of enzyme activity during evolution. J Mol Biol. 2006 Oct 20;363(2):520-30. Epub 2006 Aug 12. [PubMed:16978644 ]
General function:
Involved in catalytic activity
Specific function:
Protein serine phosphatase that dephosphorylates 'Ser-3' in cofilin and probably also dephosphorylates phospho-serine residues in DSTN. Regulates cofilin-dependent actin cytoskeleton reorganization. Required for normal progress through mitosis and normal cytokinesis. Does not dephosphorylate phospho-threonines in LIMK1. Does not dephosphorylate peptides containing phospho-tyrosine. Pyridoxal phosphate phosphatase. Has some activity towards pyridoxal 5'-phosphate (PLP), pyridoxine 5'-phosphate (PMP) and pyridoxine 5'-phosphate (PNP), with a highest activity with PLP followed by PNP.
Gene Name:
Uniprot ID:
Molecular weight:
Pyridoxal 5'-phosphate + Water → Pyridoxal + Phosphoric aciddetails
General function:
Involved in phosphatase activity
Specific function:
Phosphatase that has high activity toward pyridoxal 5'-phosphate (PLP). Also active at much lower level toward pyrophosphate, phosphoethanolamine (PEA), phosphocholine (PCho), phospho-l-tyrosine, fructose-6-phosphate, p-nitrophenyl phosphate, and h-glycerophosphate.
Gene Name:
Uniprot ID:
Molecular weight:
Pyridoxal 5'-phosphate + Water → Pyridoxal + Phosphoric aciddetails