5-Hydroxy-2-hydroxymethyl-4-pyron

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 11(SRC), determined from a log Kow of -0.64(2) and a regression-derived equation(3), indicates that kojic acid is expected to have very high mobility in soil(SRC). Volatilization of kojic acid from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 2.4X10-7 atm-cu m/mole(SRC), using a fragment constant estimation method(4). Kojic acid is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 3.2X10-6 mm Hg(SRC), determined from a fragment constant method(5). Biodegradation data were not available(SRC, 2008).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 11(SRC), determined from a log Kow of -0.64(2) and a regression-derived equation(3), indicates that kojic acid is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(3) based upon an estimated Henry's Law constant of 2.4X10-7 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). According to a classification scheme(5), an estimated BCF of 3(SRC), from its log Kow(2) and a regression-derived equation(6), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Biodegradation data were not available(SRC, 2008).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), kojic acid, which has an estimated vapor pressure of 3.2X10-6 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase kojic acid is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 6 hours(SRC), calculated from its rate constant of 6.4X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Vapor-phase kojic acid is degraded in the atmosphere by reaction with ozone radicals(SRC); the half-life for this reaction in air is estimated to be 21 hours(SRC), calculated from its rate constant of 1.3X10-17 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase kojic acid may be removed from the air by wet or dry deposition(SRC). Kojic acid contains chromophores that absorb at wavelengths >290 nm(4) and therefore may be susceptible to direct photolysis by sunlight(SRC).

Kojic acid is a fungal metabolite commonly produced by many species of Aspergillus, Acetobacter, and Penicillium. The Aspergillus flavus group has traditionally been used in the production of a number of foods, including miso (soybean paste), shoyu (soy sauce), and sake.... Because kojic acid is often produced during the fermentation of historically used dietary staples, it has a long history of consumption.

The CIR Expert Panel concluded that kojic acid is safe for use in cosmetic products up to a concentration of 1%.

Safe for use in cosmetics, with qualifications

Kojic acid acts as a competitive and reversible inhibitor of animal and plant polyphenol oxidases (tyrosinases), xanthine oxidase, and D- and some L-amino acid oxidases. Inhibition of tyrosinases prevents melanosis, while inhibition of the oxidases prevents metabolism of certain amino acids. Kojic acid also reversibly affects thyroid function by inhibiting iodine uptake, leading to decreases in thyroid hormones T3 and T4 and increases in thyroid-stimulating hormone (TSH). Increased TSH from pituitary gland in turn stimulates thyroid hyperplasia. (A3073, A3074)

The Koc of kojic acid is estimated as 11(SRC), using a log Kow of -0.64(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that kojic acid is expected to have very high mobility in soil.

Kojic acid is a fungal metabolite commonly produced by many species of Aspergillus, Acetobacter, and Penicillium. ... Different Aspergillus species are known to produce variable amounts of kojic acid.

Kojic acid is an antibiotic substance produced in an aerobic process by a variety of microorganisms from a wide-range of carbon sources(1).

/ALTERNATIVE and IN VITRO TESTS/ To discover safe and effective topical skin-lightening agents ... alkyl esters of the natural product gentisic acid (GA) ... , four putative tyrosinase inhibitors, /were evaluated/ utilizing mammalian melanocyte cell cultures and cell-free extracts. Desirable characteristics include the ability to inhibit melanogenesis in cells (IC50 less than 100 ug/mL) without cytotoxicity, preferably due to tyrosinase inhibition. Of the six esters synthesized, the smaller esters (e.g. methyl and ethyl) were more effective enzyme inhibitors (IC50 approximately 11 and 20 ug/mL, respectively). For comparison, hydroquinone (HQ), a commercial skin "bleaching" agent, was a less effective enzyme inhibitor (IC50 approximately 72 ug/mL), and was highly cytotoxic to melanocytes in vitro at concentrations substantially lower than the IC50 for enzymatic inhibition. Kojic acid was a potent inhibitor of the mammalian enzyme (IC50 approximately 6 ug/mL), but did not reduce pigmentation in cells. Both arbutin and magnesium ascorbyl phosphate were ineffective in the cell-free and cell-based assays... .

Kojic acid

Group 3: Not classifiable as to its carcinogenicity to humans

Volume 79: (2001) Some Thyrotropic Agents

2001

2000

3, not classifiable as to its carcinogenicity to humans. (L135)