Kojic acid

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Kojic acid
IUPAC name
Other names
Kojic acid, 5-Hydroxy-2-(hydroxymethyl)-4-pyrone, 2-Hydroxymethyl-5-hydroxy-γ-pyrone
501-30-4 YesY
ChEMBL ChEMBL287556 YesY
ChemSpider 3708 YesY
DrugBank DB01759 N
EC number 207-922-4
Jmol-3D images Image
KEGG C14516 YesY
PubChem 3840
RTECS number UQ0875000
UNII 6K23F1TT52 YesY
Molar mass 142.11 g/mol
Appearance white
Melting point 152 to 155 °C (306 to 311 °F; 425 to 428 K)
Acidity (pKa) 9.40[1]
R-phrases R36/37/38
S-phrases S22, S24/25
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N verify (what isYesY/N?)
Infobox references

Kojic acid is a chelation agent produced by several species of fungi, especially Aspergillus oryzae, which has the Japanese common name koji.[2][3] Kojic acid is a by-product in the fermentation process of malting rice, for use in the manufacturing of sake, the Japanese rice wine.[2] It is a mild inhibitor of the formation of pigment in plant and animal tissues, and is used in food and cosmetics to preserve or change colors of substances.[4] It forms a bright red complex with ferric ions.


13C-Labeling studies have revealed at least two pathways to kojic acid. In the usual route, dehydratase enzymes convert glucose to kojic acid. Pentoses are also viable precursors in which case dihydroxyacetone is invoked as an intermediate.[2]


Kojic acid may be used on cut fruits to prevent oxidative browning, in seafood to preserve pink and red colors, and in cosmetics to lighten skin. As an example of the latter, it is used to treat skin diseases like melasma.[5] Kojic acid also has antibacterial and antifungal properties.[citation needed]


  1. ^ Bjerrum, J., et al. Stability Constants, Chemical Society, London, 1958.
  2. ^ a b c R. Bentley, "From miso, sake and shoyu to cosmetics: a century of science for kojic acid", Nat. Prod. Rep. 2006, 23, 1046-1062.
  3. ^ Yabuta T (1924). "The constitution of kojic acid, a gamma-pyrone derivative formed by Aspergillus oryzae from carbohydrates". Journal of the Chemical Society 125: 575–587. doi:10.1039/ct9242500575. 
  4. ^ Kojic acid and enzymatic browning
  5. ^ Melasma, American Academy of Dermatology

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