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Home> Encyclopedia >Acidity Regulators>Pharmaceutical Intermediates>Cosmetic Raw Materials
Kojic acid structure
Kojic acid structure

Kojic acid

Iupac Name:5-hydroxy-2-(hydroxymethyl)pyran-4-one
CAS No.: 501-30-4
Molecular Weight:142.10944
Modify Date.: 2022-11-08 17:27
Introduction: (1) Kojic acid has a very wide range of applications in food production. In the past, kojic acid has been used in oils to prevent rancidity due to its antioxidant properties. In recent years, it has been reported in the literature that kojic acid has bactericidal and insecticidal effects. As a food preservative, preservative, and color preservative, it has obvious effects and can replace chemical Preservatives are widely used in the color protection of meat food processing, preservation of fruits and vegetables, sterilization and preservation of raw foods, and can also be used as a cut flower retaining agent to extend the preservation of flowers and shelf life. The addition of kojic acid in food will not affect its own taste, flavor and texture, but also hinder the conversion of nitrite into nitrosamines that are carcinogenic to the human body. This kind of hindering or inhibiting effect has no effect on cured meat products. The upgrade of the new generation is very important. In terms of agricultural production, kojic acid can be used as both a biological pesticide, an insecticide, and a biological fertilizer. Whether spraying or root application, it has a significant effect on increasing production and income of food and vegetables. (2) As raw materials for food flavoring agents maltol and ethyl maltol. (3) Kojic acid can be used as a raw material for the production of cephalosporin antibiotics. (4) In addition to its wide application in food processing, kojic acid also has good cosmetic effects for freckle removal and whitening. Kojic acid and its derivatives such as acetate have certain antibacterial properties, no one-time irritation and cumulative irritation to the skin, and can be used as a preservative in cosmetics and food. It can absorb ultraviolet light strongly, and can be used alone or in combination with various sunscreen products such as soap. It can treat and prevent the formation of skin spots such as liver spots, and the dosage is 1 to 2.5%. Helps maintain humidity and reduce skin wrinkles. Used in hair products to remove dandruff. (5) Kojic acid can be used as a raw material for flavoring and manufacturing larch and ethyl larch. View more+
1. Names and Identifiers
1.1 Name
Kojic acid
1.2 Synonyms

2-(hydroxymethyl)-5-hydroxy-4H-pyran-4-one 2-HYDROXYMETHYL-5-HYDROXY-4-PYRONE 2-Hydroxymethyl-5-hydroxy-Γ-pyrone 3-hydroxy-6-hydroxymethyl-4H-pyran-4-one 4H-Pyran-4-one, 5-hydroxy-2-(hydroxymethyl)- 4H-PYRAN-4-ONE,5-HYDROXY-2-(HYDROXYMETHYL) 4H-Pyran-4-one,5-hydroxy-2-(hydroxymethyl)- 5-hydroxy-2-(hydroxmetyl)-4H-pyran-4-one 5-hydroxy-2-(hydroxymethyl)-4h-pyran-4-on 5-Hydroxy-2-(hydroxymethyl)-4H-pyran-4-one 5-Hydroxy-2-(hydroxymethyl)-4-pyrone 5-hydroxy-2-(hydroxymethyl)pyran-4-one 5-Hydroxy-2-(hydroxymethyl)-γ-pyrone 5-Hydroxy-2-hydroxymethyl-4H-4-pyranone EINECS 207-922-4 kojic MFCD00006580 Pyran-4-one, 5-hydroxy-2-(hydroxymethyl) UNII-6K23F1TT52

1.3 CAS No.
1.4 CID
1.6 Molecular Formula
C6H6O4 (isomer)
1.7 Inchi
1.8 InChkey
1.9 Canonical Smiles
1.10 Isomers Smiles
2. Properties
2.1 Density
2.1 Melting point
2.1 Boiling point
401.7 °C at 760 mmHg
2.1 Refractive index
1.4434 (estimate)
2.1 Flash Point
179.9 °C
2.1 Precise Quality
2.1 PSA
2.1 logP
2.1 Λmax
2.2 Appearance
White Powder
2.3 Storage
Ambient temperatures.
2.4 Color/Form
2.5 pKa
7.9(at 25℃)
2.6 Water Solubility
2.7 Spectral Properties
MASS: 3946 (NIST/EPA/MSDC Mass Spectral database, 1990 version); 534 (National Bureau of Standards)
IR: 5765 (Coblentz Society spectral collection)
UV: 17671 (Sadtler Research Laboratories spectral collection)
1H NMR: 445 (Varian Associates NMR spectra collection)
2.8 Stability
Stable. Combustible. Incompatible with strong oxidizing agents.
2.9 StorageTemp
Store below +30°C.
3. Use and Manufacturing
3.1 Definition
ChEBI: A pyranone that is 4H-pyran substituted by a hydroxy group at position 5, a hydroxymethyl group at position 2 and an oxo group at position 4. It has been isolated from the fungus Aspergillus oryzae.
3.2 Purification Methods
Crystallise the acid from MeOH (charcoal) by adding Et2O. It sublimes at 150-200o/0.1torr. [Beilstein 18 II 57, 18 III/IV 1145, 18/2 V 516.] Kojic acid Preparation Products And Raw materials Raw materials
3.3 Usage
A naturally occurring chelation agent.
4. Safety and Handling
4.1 Hazard Codes
4.1 Risk Statements
4.1 Safety Statements
4.1 Octanol/Water Partition Coefficient
log Kow = -0.64
4.2 DisposalMethods
SRP: At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.
4.3 WGK Germany
4.3 Toxicity
Organic Compound; Ester; Food Toxin; Mycotoxin; Metabolite; Industrial/Workplace Toxin; Fungal Toxin; Natural Compound

2.Hazard identification

2.1 Classification of the substance or mixture

Not classified.

2.2 GHS label elements, including precautionary statements

Pictogram(s) No symbol.
Signal word

No signal word.

Hazard statement(s)


Precautionary statement(s)








2.3 Other hazards which do not result in classification


9. Other Information
9.0 Merck
9.1 BRN
9.2 Organic acids
Kojic acid is composed of glucose by Aspergillus Candida in 30~32 ℃ under aerobic fermentation, having the antibacterial effect of organic acid, molecular structure is for substituted gamma pyrone, in naturally occurring γ-pyranone compounds, well-known compounds are only kojic acid and maltol. In 1907, Saito is by Aspergillus isolated kojic acid crystals. In 1912, it was named by Yabuta and in 1924 to determine the structure of kojic acid. In 1953, Arnstela (surface fermentation) and in1971 Kitada Makio (submerged fermentation) using isotope tracing technique converted that kojic acid is glucose without carbon frame fracture direct oxidation and dehydration to form.
Kojic acid is present in the song, it is what people eat, safe use. In recent years, application of a large number of patent documentation report kojic acid was used in cosmetics. Tyrosinase is a key enzyme in melanin formation. Kojic acid can combine with tyrosinase copper chelate and make the loss of activity, which is the whitening effect.Clinical application and experimental results show that kojic acid can generate strong inhibitory effect on human skin melanin, safe and non-toxic, will not be caused sequelae of leukoplakia. Better combination of kojic acid and other agents (such as superoxide dismutase (SOD), placenta extract, amino acids, sunscreen agents and various kinds of plant extracts, etc.). Kojic acid is mainly used for skin whitening products, anti-aging products, sunscreen products, whitening facial cleanser and cosmetics.
Kojic acid has certain antibacterial activity. Gram negative bacteria of kojic acid sodium of sensitive degree is greater than gram positive bacteria, while most other contrary in the antimicrobial substances. Inhibitory effect of kojic acid is far below other antibacterial substances and its antibacterial activity is bacteriostatic rather than sterilization. Kojic acid on yeast, virus and phage is invalid.
9.3 Physicochemical properties
Kojic acid crystal is prism shape, acicular, colorless. Kojic acid is soluble in water, alcohol, acetone, slightly soluble in ether, ethyl acetate, chloroform and pyridine, insoluble in most other solvent. Crystallization can be in acetone, ethyl acetate solvent , also be in the 150 to 200℃ by vacuum sublimation. The melting point of the reported in the literature is 151 to 154 ℃. 5,7-diethyl kojic acid and its derivatives respectively at 315 nm and 255nm have specific absorption peaks.
Kojic acid is unstable to light and heat, the concentration 0.5% solution of kojic acid at different pH at a temperature of 100℃ treatment for 3h or sun light shined for 5h. The results at pH 5~7 solution become yellow to tan, but did not change much at pH4.
Effect of kojic acid and ferric chloride is special red, this method can be used for kojic acid quantitative. Kojic acid can be reduced fee Lin reagent and ammoniacal silver nitrate and its molecular structure near the carbonyl has a hydroxyl group, and a variety of metal to form a salt and other hydroxyl can generate ether and ester derivatives.
kojic acid
9.4 Food additives
Kojic acid may be developed as a new food additive. As a food preservative sorbic acid is more than the performance of the ideal.
Kojic acid can be used for fresh vegetables, fruits, fresh seafood, such as the cut apple, bananas, potatoes, mushrooms in 0.1% kojic acid solution leaching for 1 hour, can effectively prevent browning. Crab meat and shrimp and other seafood with 0.25%~0.6% kojic acid and 0.1% sodium sulfite solution respectively spray or infiltration method to treat Lentinus edodes, perishable vegetables such as spinach, results at room temperature for 1 day the alteration of mushroom and spinach 4 days later still keeps fresh, rarely atrophy. The dip of cut rose, rose, and so in 0.1% kojic acid solution at room temperature can be fresh for 8 days long. Kojic acid as an antioxidant can prevent oil deterioration and prevent the browning of dough. Combining with Ascorbic acid effect is better.
Kojic acid can replace part of sodium nitrite in color hair color, and can inhibit the conversion of nitrite to carcinogenic nitrosamines.
Studies suggest that the preservation mechanism of kojic acid inhibition of polyphenol oxidase in plants and animal carapace (i.e. tyrosinase).
As mentioned above, kojic acid of antibacterial, antisepsis, fresh-keeping, color protection hair color, antioxidant effect in a body is a potential and the superior performance of food additives.
9.5 Add whitening whitening cosmetics and kojic acid in food
Kojic acid is a tyrosinase inhibitor, preemptive combined with tyrosinase copper ions, making the copper ions lose effect, can inhibit the synthesis of dopachrome.
Kojic acid can inhibit 5,6-two hydroxy indole (DHI) polymerization, inhibition of DHICA oxidase activity.
Addition of kojic acid in cosmetics can have skin care, moisturizing, whitening, bright, sunscreen, freckle function. Forms have cream, lotion, emulsion, soft membrane powder, clay, powder and so on.
The earliest (1987) domestic developed and obtained the approval of the Ministry of health of the symbol (1991) is Nanjing Shi Shan Tou pharmaceutical factory 142-kojic acid freckle cream, kojic acid content is 1.5%, 2.0% in two sizes. Mainly used for pigmentation, chloasma, pregnancy spots, coffee spot), secondary pigment siderosis and melanosis, on chloasma total efficiency above 85% in the treatment of a variety of colors.
Three Ming Feng reports containing 1% or 2.5% of kojic acid cream is used for chloasma, sunshine and senile spots, inflammation that leads to pigment accumulation and patients with freckles, paint for two months, on 204 cases of statistical results is: effective symptom is alleviated) more than 93 cases (accounted for 45.6%); slightly effective (symptoms relieved slightly) more than 151 cases (74%); kojic acid dosage 1% and 2.5% difference.
Kojic acid, when heated and in the light, is easy to be yellowing, thus affecting the shelf life of kojic acid in cosmetics. Cryopreservation, adding ascorbic acid and hydroxyl methoxy phenyl ketone (2-hydroxy-4-dimethoxy diphenyl ketone) etc. shading agent can enhance its stability.
9.6 Pest control and crop yield
Kojic acid and divalent heavy metal complexes is better in the control effect of several kinds of plant fungi disease than Bordeaux mixture (a kind of insecticidal and fungicidal agent). The kojic acid complex is easy to prepare, spraying on the leaf adhesion is tightly without damage to the plants. These metals group in a non from form and kojic acid links, so toxic to humans is very low, safer than Bordeaux.
Kojic acid or nicotinic insecticides activator, when dealing with wild melon silk moth (Diaphania hyalinata L.) and (Prodenia eridania cram.), with 5% nicotine sulfate pyrophyllite powder or 5% nicotine bentonite spraying agent adding 5% kojic acid and its toxicity were increased by 35% and 50%, separately.
Kojic acid can also be used alone as a pesticide. Its mechanism is: in the coexistence and insect individual, impact on pest reproduction, disturb the hormone system, then the full eradication of the pest. Unlike conventional insecticides, not only to kill all the pests and the people, are harmless to humans and animals, and does not pollute the environment.
Nickell and Gordon, 1963) has recommended a kojic acid as plant growth stimulant. From recent years patent, kojic acid as the crop yield, increasing agent is a promising. The method is to use kojic acid or its salt spray crop leaves or invasive roots, seeds, promoting crop root, stem and leaf growth and Promoting Blossom and bear fruit, improving the yield and quality. For example: 0.01~1000mg/L kojic acid solution spraying sweet potato seedlings after planting and harvest of sweet potato starch content increased by 10%~20%, the total yield increased by 20%~30%; from flowering to harvest, in foliar spraying concentration is 100mg/L of kojic acid solution of 8 times, tomato maturity, the sugar, the individual weight were significantly increased.
China is the largest producer of hybrid rice, the hybrid rice seeds need to use "920". Considering the kojic acid production, cost advantages, it might make a difference on rice, corn, wheat, and so on of main grain crops production.
9.7 Microbial fermentation of kojic acid
Microbial fermentation of kojic acid refers to the process and technology of mass production of kojic acid by microbial fermentation method. Kojic acid is an acidic metabolites produced by Aspergillus oryzae and other microorganisms, soluble in water, ethanol or acetate. Most microorganisms can produce kojic acid for fungi, such as Aspergillus niger (Aspergillus oryzae), A.flavo-oryzae (Beige), Aspergillus flavus, Aspergillus candidus (A.flavus) (A.candidus) (A. clavatus), Aspergillus clavatus, huge Aspergillus (A.giganteus), Aspergillus fumigatus (A.fumigatus), a.tamarii (A.tamarii), Aspergillus WENTII (A.wentii) and a.glaucus (A.glaucus). Some bacteria such as rose Gluconobacter (Gluconobacter roseus), waxy Gluconobacter (G.cerinus) and Pseudomonas aeruginosa (Pseudomonas spp) can also use sugar to produce kojic acid. The basic fermentation process: Sweet potato powder by α-amylase hydrolysis→sterilizing→in the fermentation tank cooling→inoculation of Aspergillus oryzae seed from seed tank)→32 ℃and aerobic fermentation (about 5 days)→fermentation liquid filtration→ kojic acid zinc salt→decompression concentrating→crystallizing→acidification→kojic acid. kojic acid is used for manufacturing of food and daily necessities increase flavor enhancer maltol and ethyl maltol raw materials, but also the production of insecticide, fungicide and a film of dust removal agent of raw materials, and if some aliphatic carboxylic acid occurred acylation, kojic acid ester is obtained, it is raw material for manufacture of whitening cosmetics.
Reference: Zhou Deqing, Xu Shiju. Dictionary of microbiology. Tianjin: Tianjin science and Technology Press.2005.
9.8 Application and use
Used in cosmetics, food additives, pharmaceutical etc,Used for quantitative analysis of ferric iron reagent.
1.kojic acid is widely used in food production. In the pas, because of oxidation resistance, it has been used for kojic acid grease to prevent rancidity. Recent reports, kojic acid has sterilization and insect resistance, as food preservatives, preservatives, color protection agent has obvious effect, can replace chemical preservatives, which is widely used in meat dish processing color, fresh fruits and vegetables, antiseptic raw food, but also can be used as cut flowers preservation and conservation agent to extend shelf life. Kojic acid is added in the food, do not influence the taste, aroma and texture and hinder the conversion of nitrite in paired human carcinogenic nitrosamines, which hinder or inhibition of cured meat products upgrading has a very important significance. Agricultural production, kojic acid can be used as biological pesticide, used as an insecticide, and can be used as bio fertilizer, regardless of the spraying or root application, the yield of grain and vegetables income effect is remarkable.
2. as a food flavoring agent of maltol and ethyl maltol raw materials.
3.kojic acid can be used to produce cephalosporin antibiotic raw materials.
4.In addition that kojic acid is widely used in food processing, but also has good freckle, whitening beauty effect. Kojic acid and its derivatives such as acetate has certain antibacterial and on the skin without a one-time stimulus and cumulative irritation, can be used as a preservative in cosmetics and food. Can strongly absorb ultraviolet light, used lonely or compatibility with all kinds of sunscreen products such as soap and so on. Treatment and prevention and treatment of skin pigmentation such as the formation of chloasma, dosage of 1~2.5% effect is obvious. It helps to keep moisture, reduce skin wrinkles. In activities ,it can be with dandruff remover.
5. It can be used for seasoning and manufacturing raw materials of kojic acid and ethyl maltol leaves skin pigment.
9.9 Application prospect
Kojic acid which is in food, cosmetics, medicine and other aspects for the efficient application, determines its considerable economic value and great potential for development. For industrialized production of kojic acid, Japan has occupied a leading position, but with the development of society, the progress of science and technology, all the countries in the world in terms of kojic acid production have been corresponding development. These provide a broad space for the development of domestic kojic acid industry .
In short, kojic acid faces new opportunities and challenges as a new food additives in 21st century . Kojic acid is as a new type of preservative and will play an important role in food, cosmetic and pharmaceutical industry .
9.10 Extraction and purification of kojic acid
Kojic acid with divalent metal ions can form insoluble metal chelates, and this property can be utilized in the extraction. Secondly, kojic acid is soluble in water but little solubility, temperature on the solubility of great influence, is conducive to the concentration cooling crystallization.
Kojic acid can be as iron reagent. Even with the use of fermented in stainless steel tanks, the fermentation broth was also red brown, this nature influences to extraction and refining process.
Kojic acid was extracted from the fermentation broth by the copper salt precipitation, ethyl acetate extraction, ether by continuous extraction, concentration and crystallization or freezing crystallization. In 20th century 70s, the Beijing daily chemical factory used zinc salt method.
9.11 The safety of kojic acid
Japanese scholars in traditional fermented products of kojic acid to illustrate the kojic acid as the safety of food additives, which can be not limited to add.
Because kojic acid has certain antibacterial and antioxidation, in Japan kojic acid has been widely used in food processing of color protection and transportation of fruits and vegetables, fresh aquatic products, medical anti-inflammatory agent and so on. The Japanese government early in April 1988 approved in cosmetics to add kojic acid as a sunscreen, Xiaoban, white beautiful new pharmaceuticals.
China's Ministry of health approved the first Nanjing Shi Shan Tou pharmaceutical factory production of 142-kojic acid cream cosmetics for special purposes in 1991. In August of 1992, Shanghai Normal University Science and Technology Development Co., Ltd. production of kojic acid as additive in cosmetics by the Shanghai chemical toxicity assessment.
Reference: Wang Boyan, Jin Qirong. Production and application of fermentation acid. Beijing: Chinese Light Industry Press.2007.
9.12 Chemical Properties
tan powder
9.13 Uses
A naturally occurring chelation agent.
9.14 Uses
hydroxystearate nonionic solubilizer
9.15 Uses
Converted to maltol and ethyl maltol, flavor-enhancing additives. Food additive to inhibit tyrosinase.
9.16 Uses
kojic acid is a skin-lightening agent that acts through anti-oxidant activity. Kojic acid is a tyrosinase inhibitor, although it is not as effective as licorice extract. When combined with allantoin and other proper ingredients in sunscreen preparations, the mixture can inhibit uV-caused erythema and accelerate wound healing. It is also found to be skin sensitizing and can be irritating.
9.17 Definition
ChEBI: A pyranone that is 4H-pyran substituted by a hydroxy group at position 5, a hydroxymethyl group at position 2 and an oxo group at position 4. It has been isolated from the fungus Aspergillus oryzae.
9.18 General Description
Kojic acid, a tyrosinase inhibitor, is produced by several fungi species, including Aspergillus oryzae. It exhibits skin-lightening property, due to its ability to chelate the copper-containing enzyme tyrosinase in the formation of melanin. Kojic acid is also commonly used as a whitening agent in regular cosmetics, bleaching cosmetics, etc. It is found to be a therapeutic agent and helps in preventing pigmentation.
9.19 Usage
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. It is used to treat skin diseases like melasma as it has antibacterial and antifungal properties. It is used as a chelation agent that inhibits melanin production and also as a tyrosine kinase inhibitor.
10. Computational chemical data
  • Molecular Weight: 142.10944g/mol
  • Molecular Formula: C6H6O4
  • Compound Is Canonicalized: True
  • XLogP3-AA: -0.9
  • Exact Mass: 142.02660867
  • Monoisotopic Mass: 142.02660867
  • Complexity: 214
  • Rotatable Bond Count: 1
  • Hydrogen Bond Donor Count: 2
  • Hydrogen Bond Acceptor Count: 4
  • Topological Polar Surface Area: 66.8
  • Heavy Atom Count: 10
  • Defined Atom Stereocenter Count: 0
  • Undefined Atom Stereocenter Count: 0
  • Defined Bond Stereocenter Count: 0
  • Undefined Bond Stereocenter Count: 0
  • Isotope Atom Count: 0
  • Covalently-Bonded Unit Count: 1
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