Kojic acid

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Structural formula
Structure of kojic acid
Surname Kojic acid
other names
  • 5-hydroxy-2- (hydroxymethyl) -4-pyrone
Molecular formula C 6 H 6 O 4
Brief description

Colorless prismatic crystal needles

External identifiers / databases
CAS number 501-30-4
EC number 207-922-4
ECHA InfoCard 100.007.203
PubChem 3840
ChemSpider 3708
DrugBank DB01759
Wikidata Q416285
Molar mass 142.11 g mol −1
Physical state


Melting point

153-154 ° C

pK s value

7.90 (8.03)

safety instructions
GHS labeling of hazardous substances
08 - Dangerous to health


H and P phrases H: 351
P: 201-281
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Kojic acid occurs naturally in the mycelia of various fungi , especially in the Aspergillus oryzae mold . It was isolated for the first time in 1907.


Kojic acid is produced by fermenting glucose-containing solutions with Aspergillus species, mainly from the Aspergillus flavus / Aspergillus oryzae group .


With some heavy metal ions (Fe 3+ , Cu 2+ , Zn 2+ ), kojic acid forms colored, sparingly soluble chelate complexes .


Kojic acid has anti-inflammatory and antibacterial properties. However, it is mainly used because of its effect as a tyrosinase inhibitor . When applied to the skin, this property inhibits the formation of melanin and thus bleaches the skin. This effect is particularly popular in Asia, which is why there are many cosmetics with kojic acid on the market there. The use of kojic acid in cosmetic products is not regulated in the European Union; it is prohibited in Switzerland.

Individual evidence

  1. Entry on KOJIC ACID in the CosIng database of the EU Commission, accessed on July 1, 2020.
  2. a b c Entry on kojic acid. In: Römpp Online . Georg Thieme Verlag, accessed on December 29, 2014.
  3. Hermann Ammon (Ed.): Hunnius Pharmaceutical Dictionary . 8th edition, de Gruyter, Berlin 2004. ISBN 3-11-015792-6 .
  4. a b c d e data sheet Kojic acid, 99% from AlfaAesar, accessed on December 21, 2019 ( PDF )(JavaScript required) .