Melanin is a type of dark pigment that can cause skin coloration. Tyrosine is the raw material for the formation of melanin, and tyrosinase is the main rate-limiting enzyme for converting tyrosine into melanin, and its activity determines the amount of melanin formed. Tyrosinase has tyrosine hydroxylase activity (catalyzing tyrosine → dopa) and dopa oxidase activity (catalyzing dopa→ dopaquinone) and is a key factor in melanin synthesis by melanocytes[1].
Hydroquinone has the effect of inhibiting tyrosinase and was used in freckle removal and whitening cosmetics in the early stage. However, hydroquinones carry a risk of exogenous melasma and leukoplakia, and even a potential risk of sensitization and carcinogenicity[2]. Therefore, the European Union and the mainland list hydroquinone as a banned ingredient in cosmetics [3,4].
Arbutin is similar in structure to hydroquinone, has whitening effects, and is often used in cosmetics as a tyrosinase inhibitor.
Whitening mechanism
Arbutin can effectively inhibit tyrosinase activity, and by interfering with melanocytes, inhibit melanin production. Arbutin also has the effect of reducing skin pigmentation [5].
Lu Bin et al. [6] used zebrafish embryos as a model, and found through qualitative observation that
He Dun et al. [7] copied the melasma mouse model and gave arbutin intervention, and found that arbutin has an effective whitening effect, which may treat melasma by inhibiting the tyrosinase activity of melanocyte and melanoma cells, reducing free radical production, and inhibiting the formation of melanin.
Categorical comparison
According to the difference in chemical structure, arbutin can be divided into α-arbutin, β-arbutin and deoxyarbutin. β-arbutin is cheap and used more in many cosmetics, α-arbutin and deoxyarbutin are new whitening ingredients, the effect is better than β-arbutin, but SCCS (European Union Consumer Safety Committee) announced that from July 26, 2021 to ban deoxyarbutin in cosmetics, so the following is only α-arbutin and β-arbutin to make introductions.
PART 01.SOURCE DIFFERENCES
α-arbutin source pathway is narrow, rarely extracted from plants, the current synthesis methods mainly include
β-Arbutin can be obtained by 4 methods: plant extraction, plant cell culture, enzymatic transformation and chemical synthesis, currently
PART 02.WHITENING DIFFERENCES
It has been reported to be stronger than other currently known whitening active ingredients [8].
Funayama et al. [9] compared the effects of β-arbutin and α-arbutin on the tyrosinase activity of melanoma from mushrooms and mice, and the results showed that β-arbutin can inhibit tyrosinase from mushrooms and mouse melanoma by non-competitive inhibition, while α-arbutin only inhibits the tyrosinase of mouse melanoma, and the mechanism is speculated to be mixed inhibition, and the inhibition intensity of α-arbutin is 10 times that of β-arbutin.
PART 03. Stability differences
β-Arbutin breaks down under conditions to produce hydroquinone, and even promotes the hydrolysis of β-arbutin by β-glucosidase to produce hydroquinone.
α-Arbutin produces hydroquinone when pH 1.0 or 13.0 and UV irradiation.
PART 04. SECURITY DIFFERENCES
In the study of the inhibitory effect of β-arbutin and α-arbutin on melanin synthesis, the inhibitory effect of the two compounds on melanin synthesis was studied with cultured B16 melanoma cells, and it was found that α-arbutin and β-arbutin had equal levels of inhibition of tyrosinase, but α-arbutin at a concentration of 1mmol/L did not inhibit the growth of cells, while β-arbutin showed effective inhibition at the same concentration. apparently
bibliography
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[3] José MB. Commission Regulation (EU)No 344/2013 of 4 April 2013 amending Annexes II，III，V and VI to Regulation(EC)No 1223/2009 of the European Parliament and of the Council on cosmetic products， Brussels，Belgium，2014 [R]. Brussels：Official Journal of the European Union，2013.
[4] State Food and Drug Administration. Announcement on the issuance of the Safety Technical Specification for Cosmetics (2015 Edition)[R]. No. 268 of 2015.
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