Kojic acid

Kojic acid is a naturally derived compound best known for its powerful skin-brightening and pigment-correcting properties. It is produced through the fermentation of certain fungi, particularly Aspergillus oryzae, and is a byproduct of the fermentation process used in making sake, soy sauce, and rice wine. In skincare, kojic acid is widely used to reduce hyperpigmentation, dark spots, and melasma by inhibiting tyrosinase, an enzyme responsible for melanin production.

One of its primary benefits is its ability to lighten existing discoloration while preventing new pigmentation from forming. This makes it a popular ingredient in serums, creams, and masks designed for individuals dealing with sun damage, post-inflammatory hyperpigmentation (PIH), and uneven skin tone. Kojic acid is often combined with other skin-brightening agents such as vitamin C, arbutin, and licorice extract to enhance its effectiveness and provide a more even complexion.

In addition to its brightening properties, kojic acid has mild antioxidant and antimicrobial benefits, which can help protect the skin from environmental damage and reduce acne-causing bacteria. Some formulations incorporate kojic acid to address post-acne marks and scars, as it not only fades discoloration but also promotes a more radiant and refined skin texture.

Despite its efficacy, kojic acid can be irritating for some individuals, especially those with sensitive skin. It is recommended to start with lower concentrations (typically 1-2%) and gradually build up tolerance while using sunscreen daily, as kojic acid can make the skin more photosensitive. When used correctly, it is a potent yet gentle alternative to stronger depigmenting agents like hydroquinone, making it a staple in many brightening and corrective skincare treatments.

Kojic acid (Wikipedia)

Kojic acid is an organic compound with the formula HOCH₂C₅H₂O₂OH. It is a derivative of 4-pyrone that functions in nature as a chelation agent produced by several species of fungi, especially Aspergillus oryzae, which has the Japanese common name koji. Kojic acid is a by-product in the fermentation process of malting rice, for use in the manufacturing of sake, the Japanese rice wine. It is a mild inhibitor of the formation of pigment in plant and animal tissues, and is used in food and cosmetics to preserve or change colors of substances. It forms a bright red complex with ferric ions.

Kojic acid

Names
Preferred IUPAC name 5-Hydroxy-2-(hydroxymethyl)-4H-pyran-4-one
Other names Kojic acid, 5-Hydroxy-2-(hydroxymethyl)-4-pyrone, 2-hydroxymethyl-5-hydroxy-γ-pyrone
Identifiers
CAS Number	501-30-4 Y
3D model (JSmol)	Interactive image
Beilstein Reference	120895
ChEBI	CHEBI:43572 Y
ChEMBL	ChEMBL287556 Y
ChemSpider	3708 Y
DrugBank	DB01759 Y
ECHA InfoCard	100.007.203
EC Number	207-922-4
Gmelin Reference	3620
KEGG	C14516 Y
PubChem CID	3840
RTECS number	UQ0875000
UNII	6K23F1TT52 Y
CompTox Dashboard (EPA)	DTXSID2040236
InChI InChI=1S/C6H6O4/c7-2-4-1-5(8)6(9)3-10-4/h1,3,7,9H,2H2 Y Key: BEJNERDRQOWKJM-UHFFFAOYSA-N Y InChI=1/C6H6O4/c7-2-4-1-5(8)6(9)3-10-4/h1,3,7,9H,2H2
SMILES O=C1/C=C(\O/C=C1/O)CO
Properties
Chemical formula	C6H6O4
Molar mass	142.110 g·mol−1
Appearance	white
Melting point	152 to 155 °C (306 to 311 °F; 425 to 428 K)
Solubility in water	Slight
Acidity (pKa)	9.40
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H351
Precautionary statements	P201, P280, P308+P313
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references