β-arbutin, also known by its International Nomenclature of Cosmetic Ingredients (INCI) name, arbutin, is a glycosylated derivative of hydroquinone. β-Arbutin is naturally present in the leaves and bark of a variety of plants, notably the bearberry plant, Arctostaphylos uva-ursi. Utilized as a biosynthetic active ingredient in topical treatments for skin lightening, β-arbutin is aimed at addressing hyperpigmentation issues. Its mechanism of action involves inhibiting the activity of tyrosinase, an essential enzyme for melanin synthesis in the human skin, thereby leading to a reduction in hyperpigmentation. It is important to distinguish β-arbutin from its structurally similar stereoisomer, α-arbutin, which exhibits similar effects in clinical applications.[3]
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| Names | |
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| IUPAC name
4-Hydroxyphenyl-β-d-glucopyranoside
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| Systematic IUPAC name
(2R,3S,4S,5R,6S)-2-(Hydroxymethyl)-6-(4-hydroxyphenoxy)oxane-3,4,5-triol | |
Other names
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| Identifiers | |
3D model (JSmol)
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| 89673 | |
| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| DrugBank | |
| ECHA InfoCard | 100.007.138 |
| EC Number |
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| KEGG | |
| MeSH | Arbutin |
PubChem CID
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| RTECS number |
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| UNII | |
CompTox Dashboard (EPA)
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| Properties[2] | |
| C12H16O7 | |
| Molar mass | 272.25 |
| Appearance | Colorless to white solid powder |
| Melting point | 197–201 °C (387–394 °F; 470–474 K) |
| 5.0 g/100 mL | |
| Solubility | slightly soluble in ethyl ether, benzene and chloroform |
| Solubility in ethanol | soluble |
| log P | –1.35 |
| Vapor pressure | 2.3×10−12 mm Hg (25 °C) |
| Acidity (pKa) | 10.10 |
| UV-vis (λmax) | 285 nm[1] |
| Pharmacology | |
| D11 (WHO) | |
| Topically | |
| Pharmacokinetics: | |
| 0.53% percutaneous absorption[3] | |
| Legal status |
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| Hazards[2] | |
| Occupational safety and health (OHS/OSH): | |
Ingestion hazards
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Low level of toxicity |
Eye hazards
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Irritation |
Skin hazards
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Irritation |
| GHS labelling: | |
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| Warning | |
| H315, H319, H335 | |
| NFPA 704 (fire diamond) | |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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9.8 g/kg (mouse, oral), 8.7 g/kg (rat, oral), 978 mg/kg (rat, mouse, dermal) (maximum practically applicable dosage)[2] |
| Safety data sheet (SDS) | Sigma-Aldrich |
| Related compounds | |
Related compounds
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Properties
editArbutin is a compound where a glucose molecule, specifically d-glucose, is chemically bound to hydroquinone. In aqueous solutions, glucose can exist in one of three stereoisomeric forms: α, β, or γ, with the β-anomer being the predominant form.[4] The standard known form of arbutin, β-Arbutin, has a molecular formula of C12H16O7 and a molecular weight of 272.25 g/mol. Its stereoisomers, α-arbutin and γ-arbutin, share the same molecular formula and weight but are distinct in their atoms' spatial arrangement.[5]
β-Arbutin is soluble in water, presenting typically as a white powder that remains stable under standard storage conditions. It exhibits stability in both ethanol and water and demonstrates resistance to light exposure.[6] When dissolved in water, β-arbutin may undergo hydrolysis, converting to hydroquinone, which can subsequently oxidize to benzoquinone.[6]
Occurrence and preparation
editThe compound is naturally occurring and can be extracted from several plant species. Traditionally extracted from the bearberry plant (Arctostaphylos uva-ursi), it also occurs in high levels in plants in the families of Ericaceae and Saxifragaceae.[7] Others include the pear (Pyrus spp.), and certain species of wheat. It is also found in very small quantities in Viburnum opulus, Bergenia crassifolia and Schisandra chinensis.[8][9]
Synthetically, it can also be prepared from the reaction of acetobromoglucose and hydroquinone in the presence of an alkali.[10]
Uses
editThe main application of β-arbutin is in the cosmetic industry, where it is incorporated into various skin care products, including creams, serums and lotions, aimed at lightening skin tone and correcting hyperpigmentation. Its efficacy and safety profile make it a sought-after ingredient for products targeting solar lentigo, freckles, melasma, and other forms of hyperpigmentation.
Herbal medicine
editFor centuries, β-arbutin has been used in phytotherapy, or herbal medicine.[6] Extracted from the leaves of bearberry plants, it is used as a mixture with other herbal drugs as a treatment for urinary tract infections.[6]
Mechanism of action
editRegulation of melanin synthesis
editβ-Arbutin acts as an enzyme inhibitor of cellular tyrosinase by inactivating it.[4] Tyrosinase is an enzyme needed in melanin synthesis in the melanin producing cell of the skin, the melanocyte. By reducing the activity of tyrosinase, β-arbutin reduces the synthesis of melanin, leading to a lighter skin tone and the diminished appearance of hyperpigmentation. It is not as potent an inhibitor of tyrosinase as α-arbutin.[6]
It has also been shown act as a substrate for tyrosinase.[4] Tyrosinase catalyses the hydroxylation of tyrosine, an amino acid, to l-DOPA (levodopa) and the oxidation of d-DOPA to dopaquinone which is then further metabolised to melanin. β-Arbutin is thought to have structural similarities to the substrate tyrosine, and this may inhibit the activity of tyrosinase.[3][11]
Decomposition into hydroquinone
editConflicting evidence shows that β-arbutin may also work by being decomposed into hydroquinone. If this occurs, the amount of hydroquinone created by decomposition would be small and its contribution to inhibiting the creation of melanin as small.[4]
Safety and regulation
editβ-Arbutin is generally considered safe for topical application in cosmetic products. However, its usage concentrations in the European Union (EU) are restricted by the European Commission Scientific Committee on Consumer Safety to 7% in facial creams, provided the contamination of hydroquinone remains below 1 ppm.[3]
Skin-lightening agent
editBearberry extract is used in skin lightening treatments designed for long term and regular use. An active agent in brands of skin lightening preparations, it is more expensive than traditional skin lightening ingredients like hydroquinone, which is now banned in many countries. In vitro studies of human melanocytes exposed to arbutin at concentrations below 300 μg/mL reported decreased tyrosinase activity and melanin content with little evidence of cytotoxicity.[12]
Risks
editArbutin is glucosylated hydroquinone,[13] and may carry similar cancer risks,[14][unreliable source?] although there are also claims that arbutin reduces cancer risk.[15] The German Institute of Food Research in Potsdam found that intestinal bacteria can transform arbutin into hydroquinone, which creates an environment favorable for intestinal cancer.[16]
See also
editReferences
edit- ^ "SCCS (Scientific Committee on Consumer Safety), Opinion on the safety of alpha- (CAS No. 84380-018, EC No. 617-561-8) and beta-arbutin (CAS No. 497-76-7, EC No. 207-8503) in cosmetic products, preliminary version of 15-16 March 2022, final version of 31 January 2023, SCCS/1642/22" (PDF). European Commission. 2023-02-01. Retrieved 2023-03-07.
- ^ a b c Sccs; Degen, Gisela H. (2015). "Opinion of the Scientific Committee on Consumer Safety (SCCS) – Opinion on the safety of the use of β-arbutin in cosmetic products". Regulatory Toxicology and Pharmacology. 73 (3): 866–867. doi:10.1016/j.yrtph.2015.10.008.
- ^ a b c d Scientific Committee on Consumer Safety (SCCS) (1 February 2023). "Opinion on the safety of alpha- (CAS No. 84380-018, EC No. 617-561-8) and beta-arbutin (CAS No. 497-76-7, EC No. 207-8503) in cosmetic products, preliminary version of 15–16 March 2022, final version of 31 January 2023, SCCS/1642/22" (PDF). European Commission (Expert Opinion). Retrieved 7 March 2024.
- ^ a b c d Boo, Yong Chool (2021-07-15). "Arbutin as a Skin Depigmenting Agent with Antimelanogenic and Antioxidant Properties". Antioxidants. 10 (7): 1129. doi:10.3390/antiox10071129. ISSN 2076-3921. PMC 8301119. PMID 34356362.
- ^ Chemistry (IUPAC), The International Union of Pure and Applied. "IUPAC - stereoisomerism (S05983)". goldbook.iupac.org. doi:10.1351/goldbook.S05983. Retrieved 2024-03-07.
- ^ a b c d e Migas, Piotr; Krauze-Baranowska, Mirosława (2015-09-01). "The significance of arbutin and its derivatives in therapy and cosmetics". Phytochemistry Letters. 13: 35–40. doi:10.1016/j.phytol.2015.05.015. ISSN 1874-3900.
- ^ Garcia-Jimenez, Antonio; Teruel-Puche, Jose Antonio; Berna, Jose; Rodriguez-Lopez, José Neptuno; Tudela, Jose; Garcia-Canovas, Francisco (2017-05-11). "Action of tyrosinase on alpha and beta-arbutin: A kinetic study". PLOS ONE. 12 (5): e0177330. Bibcode:2017PLoSO..1277330G. doi:10.1371/journal.pone.0177330. ISSN 1932-6203. PMC 5426667. PMID 28493937.
- ^ Carmen Pop; Laurian Vlase; Mircea Tamas (2009). "Natural Resources Containing Arbutin. Determination of Arbutin in the Leaves of Bergenia crassifolia (L.) Fritsch. acclimated in Romania". Not. Bot. Hort. Agrobot. Cluj. 37 (1): 129–132. Archived from the original on 2011-08-23.
- ^ Dusková J, Dusek J, Jahodár L, Poustka F (2005). "[Arbutin, salicin: the possibilities of their biotechnological production]". Ceska Slov Farm. 54 (2): 78–81. PMID 15895970.
- ^ "Hawley's Condensed Chemical Dictionary, 15th ed By Richard J. Lewis, Sr. John Wiley & Sons, Inc.: Hoboken, NJ. 2007. x 1380 pp. $150.00. ISBN 978-0-471-76865-4". Journal of the American Chemical Society. 129 (16): 5296. 2007-03-20. doi:10.1021/ja0769144. ISSN 0002-7863.
- ^ Zhu, Wenyuan; Gao, Jie (April 2008). "The Use of Botanical Extracts as Topical Skin-Lightening Agents for the Improvement of Skin Pigmentation Disorders". Journal of Investigative Dermatology Symposium Proceedings. 13 (1): 20–24. doi:10.1038/jidsymp.2008.8. ISSN 1087-0024.
- ^ Arbutin Archived May 27, 2010, at the Wayback Machine, Supporting Nomination for Toxicological Evaluation by the National Toxicology Program
- ^ O'Donoghue, J L (September 2006). "Hydroquinone and its analogues in dermatology – a risk-benefit viewpoint". Journal of Cosmetic Dermatology. 5 (3): 196–203. doi:10.1111/j.1473-2165.2006.00253.x. PMID 17177740. S2CID 38707467.
The potential toxicity of HQ (hydroquinone) is dependent on the route of exposure
- ^ "Smart Skin Care: Treatment of hyperpigmentation problems / skin lightening". www.smartskincare.com.
- ^ Bowman, Lee. July 25, 2005. Scripps Howard News Service. High yuck factor not necessarily good for us anymore Archived September 28, 2007, at the Wayback Machine
- ^ Blaut M, Braune A, Wunderlich S, Sauer P, Schneider H, Glatt H (2006). "Mutagenicity of arbutin in mammalian cells after activation by human intestinal bacteria". Food Chem. Toxicol. 44 (11): 1940–7. doi:10.1016/j.fct.2006.06.015. PMID 16904805.