|Preferred IUPAC name
Kojic acid, 5-Hydroxy-2-(hydroxymethyl)-4-pyrone, 2-hydroxymethyl-5-hydroxy-γ-pyrone
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||142.110 g·mol−1|
|Melting point||152 to 155 °C (306 to 311 °F; 425 to 428 K)|
|P201, P280, P308+P313|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
(what is ?)
Kojic acid is an organic compound with the formula HOCH2C5H2O2OH. It is a derivative of 4-pyrone that functions in nature as a chelation agent produced by several species of fungi, especially Aspergillus oryzae, which has the Japanese common name koji. Kojic acid is a by-product in the fermentation process of malting rice, for use in the manufacturing of sake, the Japanese rice wine. 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. 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.
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. Kojic acid also has antibacterial and antifungal properties. The cocrystals of kojic acid with quercetin were found to have two times better cytotoxic activity to human cervical cancer cells (HeLa) and human colon cancer cells (Caco-2) in comparison with quercetin itself.
Kojic acid has been shown to protect Chinese hamster ovary cells against ionizing radiation-induced damage. When exposed to a lethal dose of 3 Gy gamma radiation, dogs pretreated with kojic acid had a 51-day survival rate of 66.7% while the control group died within 16 days.
Deprotonation of the ring-OH group converts kojic acid to kojate. Kojate chelates to iron(III), forming a red complex Fe(HOCH2C5OH2O2)3. This kind of reaction may be the basis of the biological function of kojic aicd, that is, to solubilize ferric iron.
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- Melasma Archived 2009-12-23 at the Wayback Machine, American Academy of Dermatology
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- Safety MSDS data
- Mohajer, Fatemeh; Mohammadi Ziarani, Ghodsi (2021). "An Overview of Quantitative and Qualitative Approaches on the Synthesis of Heterocyclic Kojic Acid Scaffolds through the Multi-Component Reactions". Heterocycles. Japan Institute of Heterocyclic Chemistry. 102 (2): 211. doi:10.3987/REV-20-936.