Kojic acid is a chelating agent produced by several species of fungi, in particular the species Aspergillus oryzae, whose common name in Japanese is Koji, a byproduct of the fermentation process of malted rice, which is used in the production of Sake, the Japanese rice wine.
It is a weak inhibitor of the formation of pigments in plant and animal tissues and is used in the food and cosmetics industry to conserve products or to vary their colour. With ferric ions forms a complex of bright red color. It can be used on chopped fruit to prevent oxidative browning, in seafood to conserve pink and red colors and in cosmetics to lighten the skin. An example of the latest type of use is its use to treat skin diseases such as melasma. Kojic acid also has antibacterial and antifungal properties.
What is the use of Kojic acid?
Treatments based on this acid, in fact, are used in addition to cosmetics also in dermatology. The main characteristic of its action is due to the fact that, penetrating deep, it blocks the enzymes that make the melanin form.
In other words, it induces a functional suppression of tyrosinase by subtraction (chelation) of the copper ion present in the enzyme.
The Kojic acid molecule is almost equal to that of tyrosine as well as, chemically, it resembles tyrosinase (both are enzymes). Since chemistry has the advantage, the Kojic acid molecule binds with tyrosinase.
This is good because if it was linked to tyrosine it would have favoured the production of melanin. That is, certain reactions would have occurred for which the tyrosinase would have turned into melanin, that is the appearance of stains on the skin.
In Summary, it suppresses the production of melanin and attacks that already formed by Decolorandola, and thus clearing the stains.