Kojic Dipalmitate

What is kojic dipalmitate?

Kojic dipalmitate is an ester of kojic acid, an organic acid produced by some fungi during the fermentation process (R). It can be prepared by the esterification of kojic acid and palmitic acid in an organic solvent (R).

Is kojic dipalmitate stable?

Kojic dipalmitate has been claimed to be more stable than kojic acid, which is sensitive to heat and light (R).

Still, stability studies show that formulations of kojic dipalmitate are also affected by heat. Gel formulations containing 1% kojic dipalmitate were more stable when stored at 8°C or 25°C, but colour changes, pH decreases, increases in electrical conductivity and slight liquefaction were sometimes detected after storage at 40°C for 3 months (R). The kojic dipalmitate content loaded in nanoemulsions was likewise virtually unchanged when it was refrigerated for a month at 8°C, but only 70% of the original amount remained when it was kept at room temperature, and a mere 25% remained when it was stored at 40°C (R).

Under conditions of oxidative stress however, kojic dipalmitate is much less stable than kojic acid. As much as 35% of kojic dipalmitate degraded after just 5 minutes of exposure to 1.5% hydrogen peroxide. This compares unfavourably to kojic acid, where a loss of 30% was observed only after 48 hours (R).

Does kojic dipalmitate get absorbed?

The lipophilicity of kojic dipalmitate implies that it should have better skin absorption compared to kojic acid, which is soluble in water.

In a study on pig ear skin, kojic dipalmitate was found to be retained mainly in the stratum corneum of the skin, with a smaller amount reaching the epidermis, but it was not detected in the dermis (R). Another study on rat skin suggested that the main pathway by which kojic dipalmitate penetrates the skin is through the hair follicles (R).

Lipid-based carriers called ethosomes, which contain the penetration enhancer ethanol, have also been shown to increase the deposition of kojic dipalmitate in the skin (R).

What happens after kojic dipalmitate is absorbed?

Kojic dipalmitate is hydrolysed by enzymes called esterases that are found in skin cells, leading to the release of kojic acid (R).