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.[2][3][4] 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.[5] It forms a bright red complex with ferric ions.[6]
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| Names | |
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| Preferred IUPAC name
5-Hydroxy-2-(hydroxymethyl)-4H-pyran-4-one | |
| Other names
Kojic acid, 5-Hydroxy-2-(hydroxymethyl)-4-pyrone, 2-hydroxymethyl-5-hydroxy-γ-pyrone
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| Identifiers | |
3D model (JSmol)
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| 120895 | |
| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| DrugBank | |
| ECHA InfoCard | 100.007.203 |
| EC Number |
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| 3620 | |
| KEGG | |
PubChem CID
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| RTECS number |
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| C6H6O4 | |
| Molar mass | 142.110 g·mol−1 |
| Appearance | white |
| Melting point | 152 to 155 °C (306 to 311 °F; 425 to 428 K) |
| Slight | |
| Acidity (pKa) | 9.40[1] |
| Hazards | |
| GHS labelling: | |
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| Warning | |
| H351 | |
| P201, P280, P308+P313 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Biosynthesis
edit13C-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]
Applications
editKojic 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.[7] Kojic acid also has antibacterial and antifungal properties.[citation needed]
Uses of Kojic Acid
editKojic acid’s primary use is for skin lightening, but it also serves other functions in the beauty industry.
Skin Lightening
editKojic acid is widely used in products aimed at lightening skin tone. People seeking to reduce the appearance of uneven pigmentation or brighten their complexion often turn to products that contain kojic acid.
Dark Spot Reduction
editKojic acid is particularly effective at reducing dark spots caused by sun exposure, acne scars, or aging. By inhibiting melanin production, it gradually lightens these spots over several weeks of consistent use.
Treatment of Melasma
editMelasma is a common condition where dark patches develop on the skin, often due to hormonal changes such as pregnancy or contraceptive use. Kojic acid is a gentle yet effective treatment option for melasma, as it lightens the pigmented areas without the harsh side effects of stronger bleaching agents.
Hyperpigmentation Treatment
editHyperpigmentation, characterized by darker patches of skin, is often caused by sun damage, acne, or inflammation. Kojic acid is a go-to treatment for hyperpigmentation because of its ability to target and lighten these areas over time.
Anti-Aging Benefits
editBeyond its brightening effects, kojic acid also helps improve the overall appearance of the skin by diminishing the appearance of fine lines, wrinkles, and age spots. Its antioxidant properties further boost its role in fighting signs of aging.
Acne Scar Reduction
editAcne scars can leave behind unsightly dark marks, which kojic acid can help to reduce. Although it won’t affect the texture of scars, its depigmenting properties can help lighten post-acne marks, making them less noticeable.
Kojic Acid for Sensitive Skin
editKojic acid is a relatively gentle option for those with sensitive skin who may not be able to tolerate stronger acids like glycolic or salicylic acid. When used in moderation and combined with a hydrating regimen, kojic acid can brighten and even skin tone without causing irritation.
Chemical reactions
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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 acid, that is, to solubilize ferric iron.[9]
Being a multifunctional molecule, kojic acid has diverse organic chemistry. The hydroxymethyl group gives the chloromethyl derivative upon treatment with thionyl chloride.[10]
Safety
editKojic acid may be weakly carcinogenic, according to some animal studies. It is not believed to reach carcinogenic thresholds in human skin, and is demonstrably safe at the level used in cosmetics.[11]
References
edit- ^ Bjerrum, J., et al. Stability Constants, Chemical Society, London, 1958.
- ^ a b c Bentley, R. (2006). "From miso, sake and shoyu to cosmetics: a century of science for kojic acid". Nat. Prod. Rep. 23 (6): 1046–1062. doi:10.1039/b603758p. PMID 17119644.
- ^ Yabuta T (1924). "The constitution of kojic acid, a γ-pyrone derivative formed by Aspergillus oryzae from carbohydrates". Journal of the Chemical Society. 125: 575–587. doi:10.1039/ct9242500575.
- ^ Parvez, Shoukat; Kang, Moonkyu; Chung, Hwan-Suck; Cho, Chongwoon; Hong, Moo-Chang; Shin, Min-Kyu; Bae, Hyunsu (2006). "Survey and mechanism of skin depigmenting and lightening agents". Phytotherapy Research. 20 (11): 921–34. doi:10.1002/ptr.1954. PMID 16841367. S2CID 22156361.
- ^ "Kojic acid and enzymatic browning]". Food and Agriculture Organization of the United Nations. 2000. Archived from the original on 2008-03-04.
- ^ Nurchi, Valeria M.; Lachowicz, Joanna I.; Crisponi, Guido; Murgia, Sergio; Arca, Massimiliano; Pintus, Anna; Gans, Peter; Niclos-Gutierrez, Juan; Domínguez-Martín, Alicia; Castineiras, Alfonso; Remelli, Maurizio (2011-05-27). "Kojic acid derivatives as powerful chelators for iron(III) and aluminium(III)". Dalton Transactions. 40 (22): 5984–5998. doi:10.1039/C1DT00005E. ISSN 1477-9234. PMID 21552634.
- ^ Melasma Archived 2009-12-23 at the Wayback Machine, American Academy of Dermatology
- ^ "Kojic Acid - Healthcopeia". 2024-10-21. Retrieved 2024-10-21.
- ^ Zaremba, K.; Lasocha, W.; Adamski, A.; Stanek, J.; Pattek-Janczyk, A. (2007). "Crystal Structure and Magnetic Properties of Tris(2-hydroxymethyl-4-oxo-4H-pyran- 5-olato-κ2O5,O4)iron(III)". Journal of Coordination Chemistry. 60 (14): 1537–1546. doi:10.1080/00958970601084243. S2CID 97627687.
- ^ Agyemang, Nana; Murelli, Ryan P. (2019). "Synthesis of 5-Hydroxy-4-methoxy-2-methylpyrylium Trifluoromethanesulfonate from Kojic Acid". Organic Syntheses. 96: 494–510. doi:10.15227/orgsyn.096.0494. S2CID 238194561.
- ^ "Final Report of the Safety Assessment of Kojic Acid". ResearchGate. December 2010.
External links
edit- 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. 102 (2). Japan Institute of Heterocyclic Chemistry: 211. doi:10.3987/REV-20-936.