Kojic Acid

It is a natural product present in various fungi and is also produced as a by-product during the fermentation of some foods such as soy sauce, rice wine, and Japanese sake. It is naturally found in Aspergillus, Aspergillus terricola and Marrubium cylleneum. For example, it has been isolated from the fungus Aspergillus oryzae.

It has the ability to prevent the formation of tyrosine, an amino acid that is needed to form melanin. Melanin is a pigment that provides colour to hair, skin, eyes, etc. So, kojic acid may cause a lightening effect owing to its ability to inhibit the production of melanin.

Kojic Acid Structure

Its chemical formula is C₆H₆O₄. Kojic acid is a pyranone wherein 4H-pyran is substituted by a hydroxy group at position 5.

Chemical properties of Kojic acid

• It exists as a crystalline powder.
• Its color may vary from white to beige-brown.
• It is soluble in water, alcohol, and acetone, however, slightly soluble in ether, ethyl acetone, chloroform, etc.
• It is unstable to heat and light.
• It is combustible and is incompatible with strong oxidizing agents.
• Its melting point is 152 to 155 degrees Celsius.
• Its boiling point is 179.65 degrees Celsius.
• Its density is around 1.1712 and its refractive index is 1.4434.
• The pka of kojic acid is 7.9 at 25 degrees Celsius.

Preparation of Kojic Acid

It can be produced chemically from pyranoid 3, 2-enolones. Whereas, biologically it can be prepared from direct fermentation of glucose using A. oryzae and A. flavus.

Indian Science and Technology and Innovation (ISIT) has introduced a method to produce and purify Kojic acid through fermentation of marine fungus Aspergillus spp and Penicillium spp. A lot of research is going on Kojic acid production owing to its economic potential in the field of food, medicine, cosmetics and agriculture. Some of the major uses of Kojic acid are as below:

Kojic Acid Uses:

• It is used as an inhibitor of polyphenol oxidase, an enzyme that causes the blackening of agricultural products and cut fruits.
• It is used in medicines as an antioxidant owing to its ability to destroy free radicals.
• It is also used in cosmetics like gels and soaps as it helps lighten skin by preventing the enzyme tyrosinase which is responsible for producing melanin: skin pigment that gives color to the skin.
• It helps reduce the appearance of age spots and sun damage. Thus it reduces the effect of aging.
• It is also helpful in reducing melasma wherein the skin gets darker due to pregnancy.
• It reduces the appearance of scars by reducing the dark pigmentation or by lightening the scar.
• It is also used to prevent and treat some fungal infections owing to its antifungal properties such as it helps prevent athlete's foot and yeast infections.
• It also offers various antibacterial benefits. For example, it reduces the chances of developing common skin infections.

Health Hazards

Although Kojic acid is found in many products and is considered safe, there are some possible risks associated with the use of products containing kojic acid. Here are some common side effects.

The use of kojic acid increases the chances of developing a sunburn. It does not aid the formation of melanin that protects the skin from sun damage.

It may cause contact dermatitis in people who have sensitive skin.

The manufacturers may increase the kojic acid in products like creams, soaps, serums, etc. Its higher concentration may cause irritation.

So, kojic acid may be helpful for some people and may not for others. So, one should talk to a dermatologist before using products containing kojic acid.