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Record Information
Creation Date2005-11-16 15:48:42 UTC
Update Date2014-10-09 20:53:53 UTC
Secondary Accession NumbersNone
Metabolite Identification
Common Name4-Pyridoxic acid
Description4-Pyridoxic acid is the catabolic product of vitamin B6 (also known as pyridoxine, pyridoxal and pyradoxamine) which is excreted in the urine. Urinary levels of 4-pyridoxic acid are lower in females than in males and will be reduced in persons with riboflavin deficiency. 4-Pyridoxic acid is formed by the action of aldehyde oxidase I (an endogenous enzyme) and by microbial enzymes (pyridoxal 4-dehydrogenase), an NAD-dependent aldehyde dehydrogenase. 4-pyridoxic acid can be further broken down by the gut microflora via 4-pyridoxic acid dehydrogenase. This enzyme catalyzes the four electron oxidation of 4-pyridoxic acid to 3-hydroxy-2-methylpyridine-4,5-dicarboxylate, using nicotinamide adenine dinucleotide as a cofactor.
  1. 2-Methyl-3-hydroxy-4-carboxy-5-hydroxymethylpyridine
  2. 3-Hydroxy-5-(hydroxymethyl)-2-methyl-4-pyridinecarboxylate
  3. 3-Hydroxy-5-(hydroxymethyl)-2-methyl-4-pyridinecarboxylic acid
  4. 3-Hydroxy-5-(hydroxymethyl)-2-methyl-Isonicotinate
  5. 3-Hydroxy-5-(hydroxymethyl)-2-methyl-Isonicotinic acid
  6. 3-Hydroxy-5-(hydroxymethyl)-2-methylisonicotinate
  7. 3-Hydroxy-5-(hydroxymethyl)-2-methylisonicotinic acid
  8. 3-Hydroxy-5-hydroxymethyl-2-methyl-isonicotinate
  9. 3-Hydroxy-5-hydroxymethyl-2-methyl-isonicotinic acid
  10. 3-Hydroxy-5-hydroxymethyl-2-methyl-isonicotinsaeure
  11. 4-Pyridoxate
  12. 4-Pyridoxinate
  13. 4-Pyridoxinecarboxylate
  14. 4-Pyridoxinecarboxylic acid
  15. 4-Pyridoxinic acid
  16. 4-Pyridoxinsaeure
  17. 4-Pyridoxylate
  18. 4-Pyridoxylic acid
Chemical FormulaC8H9NO4
Average Molecular Weight183.1614
Monoisotopic Molecular Weight183.053157781
IUPAC Name3-hydroxy-5-(hydroxymethyl)-2-methylpyridine-4-carboxylic acid
Traditional Namepyridoxic acid
CAS Registry Number82-82-6
InChI Identifier
Chemical Taxonomy
KingdomOrganic Compounds
Super ClassAromatic Heteromonocyclic Compounds
ClassPyridines and Derivatives
Sub ClassPyridinecarboxylic Acids and Derivatives
Other Descriptors
  • Pyridines and Derivatives
  • hydroxymethylpyridine(ChEBI)
  • methylpyridines(ChEBI)
  • monohydroxypyridine(ChEBI)
  • vitamin B6(ChEBI)
  • Carboxylic Acid
  • Primary Alcohol
Direct ParentPyridinecarboxylic Acids and Derivatives
StatusDetected and Quantified
  • Endogenous
BiofunctionNot Available
ApplicationNot Available
Cellular locations
  • Cytoplasm
  • Extracellular
Physical Properties
Experimental Properties
Melting Point247 - 248 °CNot Available
Boiling PointNot AvailableNot Available
Water SolubilityNot AvailableNot Available
LogPNot AvailableNot Available
Predicted Properties
Water Solubility8.71ALOGPS
pKa (Strongest Acidic)2.55ChemAxon
pKa (Strongest Basic)4.09ChemAxon
Physiological Charge-1ChemAxon
Hydrogen Acceptor Count5ChemAxon
Hydrogen Donor Count3ChemAxon
Polar Surface Area90.65 Å2ChemAxon
Rotatable Bond Count2ChemAxon
Refractivity44.55 m3·mol-1ChemAxon
Polarizability17.19 Å3ChemAxon
Biological Properties
Cellular Locations
  • Cytoplasm
  • Extracellular
Biofluid Locations
  • Blood
  • Saliva
  • Urine
Tissue Location
  • Bladder
  • Erythrocyte
  • Kidney
  • Liver
Vitamin B6 MetabolismSMP00017map00750
Normal Concentrations
BloodDetected and Quantified0.027 (0.0062-3.14) uMAdult (>18 years old)BothNormal details
BloodDetected and Quantified0.040 +/- 0.007 uMAdult (>18 years old)BothNormal
    • Geigy Scientific ...
BloodDetected and Quantified0.0071 +/- 0.005 uMAdult (>18 years old)FemaleNormal details
BloodDetected and Quantified0.0097 +/- 0.00665 uMAdult (>18 years old)MaleNormal details
SalivaDetected but not QuantifiedNot ApplicableAdult (>18 years old)Both
    • Dame, ZT. et al. ...
UrineDetected and Quantified> 0.33 umol/mmol creatinineAdult (>18 years old)FemaleNormal details
UrineDetected and Quantified0.78 +/- 0.45 umol/mmol creatinineAdult (>18 years old)Both
UrineDetected and Quantified3.1 (0.4-7.5) umol/mmol creatinineAdult (>18 years old)Both
UrineDetected and Quantified> 3.0 umol/mmol creatinineChildren (1-13 years old)BothNormal details
UrineDetected and Quantified2.99 +/- 5.25 umol/mmol creatinineInfant (0-1 year old)BothNormal details
Abnormal Concentrations
UrineDetected and Quantified1414.9 +/- 737.8 umol/mmol creatinineAdult (>18 years old)Both
Critically ill
Associated Disorders and Diseases
Disease ReferencesNone
Associated OMIM IDsNone
DrugBank IDNot Available
DrugBank Metabolite IDNot Available
Phenol Explorer Compound IDNot Available
Phenol Explorer Metabolite IDNot Available
FoodDB IDFDB021874
KNApSAcK IDNot Available
Chemspider ID6467
KEGG Compound IDC00847
BioCyc IDCPD-1112
BiGG ID36190
Wikipedia LinkNot Available
NuGOwiki LinkHMDB00017
Metagene LinkHMDB00017
PubChem Compound6723
PDB IDNot Available
ChEBI ID17405
Synthesis ReferenceSenkuma, Masahiko; Imada, Katsumi; Sato, Masatada. Preparation of 4-pyridoxic acid. Jpn. Kokai Tokkyo Koho (1992), 2 pp.
Material Safety Data Sheet (MSDS)Download (PDF)
General References
  1. 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
  2. Kodentsova VM, Vrzhesinskaia OA, Sokol'nikov AA, Beketova NA, Spirichev VB: [The effect of riboflavin supply on metabolism of water-soluble vitamins] Vopr Med Khim. 1993 Sep-Oct;39(5):29-33. Pubmed: 8279138
  3. Masse PG, Mahuren JD, Tranchant C, Dosy J: B-6 vitamers and 4-pyridoxic acid in the plasma, erythrocytes, and urine of postmenopausal women. Am J Clin Nutr. 2004 Oct;80(4):946-51. Pubmed: 15447904
  4. Huang YC, Chang HH, Huang SC, Cheng CH, Lee BJ, Cheng SY, Su KH: Plasma pyridoxal 5'-phosphate is a significant indicator of immune responses in the mechanically ventilated critically ill. Nutrition. 2005 Jul-Aug;21(7-8):779-85. Pubmed: 15975484
  5. Ericson KL, Mahuren JD, Zubovic YM, Coburn SP: Use of chlorite to improve HPLC detection of pyridoxal 5'-phosphate. J Chromatogr B Analyt Technol Biomed Life Sci. 2005 Sep 5;823(2):218-20. Pubmed: 16054880
  6. Driskell JA, Chrisley BM: Plasma B-6 vitamer and plasma and urinary 4-pyridoxic acid concentrations in young women as determined using high performance liquid chromatography. Biomed Chromatogr. 1991 Sep;5(5):198-201. Pubmed: 1742549
  7. Chiang EP, Smith DE, Selhub J, Dallal G, Wang YC, Roubenoff R: Inflammation causes tissue-specific depletion of vitamin B6. Arthritis Res Ther. 2005;7(6):R1254-62. Epub 2005 Sep 13. Pubmed: 16277678
  8. Rybak ME, Pfeiffer CM: Clinical analysis of vitamin B(6): determination of pyridoxal 5'-phosphate and 4-pyridoxic acid in human serum by reversed-phase high-performance liquid chromatography with chlorite postcolumn derivatization. Anal Biochem. 2004 Oct 15;333(2):336-44. Pubmed: 15450810
  9. Huang YC, Chang SJ, Chiu YT, Chang HH, Cheng CH: The status of plasma homocysteine and related B-vitamins in healthy young vegetarians and nonvegetarians. Eur J Nutr. 2003 Apr;42(2):84-90. Pubmed: 12638029
  10. Midttun O, Hustad S, Solheim E, Schneede J, Ueland PM: Multianalyte quantification of vitamin B6 and B2 species in the nanomolar range in human plasma by liquid chromatography-tandem mass spectrometry. Clin Chem. 2005 Jul;51(7):1206-16. Pubmed: 15976101
  11. Chang SJ, Huang YC, Hsiao LJ, Lee YC, Hsuen SY: Determination of vitamin B-6 estimated average requirement and recommended dietary allowance for children aged 7-12 years using vitamin B-6 intake, nutritional status and anthropometry. J Nutr. 2002 Oct;132(10):3130-4. Pubmed: 12368406


General function:
Involved in oxidoreductase activity
Specific function:
Not Available
Gene Name:
Uniprot ID:
Molecular weight:
Pyridoxal + Oxygen + Water → 4-Pyridoxic acid + Hydrogen peroxidedetails
  1. Stanulovic M, Jeremic V, Leskovac V, Chaykin S: New pathway of conversion of pyridoxal to 4-pyridoxic acid. Enzyme. 1976;21(4):357-69. Pubmed: 939227