Abstract: Arbutin is a well-established cosmetic ingredient widely used for skin brightening and the management of hyperpigmentation. Derived naturally from plants such as bearberry or produced biotechnologically as α-arbutin, it offers a favourable balance between cosmetic effectiveness and safety. This article reviews the chemical characteristics, mechanisms of action and cosmetic benefits of arbutin, with particular focus on its tyrosinase-inhibiting, antioxidant and anti-inflammatory properties. Comparative insights with hydroquinone are discussed, alongside formulation challenges, stability considerations and regulatory safety limits. Practical guidance is provided to support the effective and responsible use of arbutin in modern cosmetic formulations.
Marolt A. Arbutin: A valuable botanical ingredient. Cos ACTIVE J. 2025;3:30–36
INTRODUCTION
α-arbutin is an established cosmetic ingredient valued for its ability to reduce hyperpigmentation, even skin tone and combat visible signs of ageing. Due to its proven safety and effectiveness, it has become increasingly popular in skincare, where it is used in serums, creams and other products to improve skin tone and protect against oxidative stress (1).
Arbutin is a naturally occurring compound found in several plants, including the species of Bergenia, Pyrus and Vaccinium (2). The richest natural source is bearberry (Arctostaphylos uva-ursi), where it can reach concentrations of 5–10% (3, 4). Due to this high content, bearberry extracts are highly valued by the cosmetic and pharmaceutical industries (2).
Arbutin with a chemical name 4-hydroxyphenyl-D-glucopyranoside is a glycosidic derivative of hydroquinone (Figure 1). The molecule exists in two isomeric forms (5):
– α-arbutin: It only occurs in bearberry in trace or negligible amounts. It is produced synthetically, most commonly by biotechnological microbial or enzymatic processes. As a cosmetic ingredient, it shows similar stability but higher activity than β-arbutin (6).
– β-arbutin: It occurs naturally but is less potent compared to α-arbutin (6).
Arbutin’s ability to inhibit melanin synthesis makes it an essential ingredient in skin-lightening products. It is also valued for its anti-inflammatory, antimicrobial and antioxidant properties. Studies show that α-arbutin is 10 times more effective than β-arbutin, making it a preferred choice in cosmetic formulations (6). Details of its effectiveness and use in cosmetic formulations are discussed in the following sections.
MECHANISM OF ACTION AND BENEFITS
Skin brightening and anti-hyperpigmentation
Skin discolouration is the result of altered melanin production. Melanins are natural pigments in the skin and chemically a group of heterogeneous indole polymers that range in colour from yellow to brown. The biosynthesis of melanin depends primarily on the activity of tyrosinase and UV radiation. Tyrosinase plays a key role in the conversion of tyrosine to L-DOPA, the oxidation of L-DOPA to dopaquinone and the further conversion of dopaquinone to the end product – melanin. Melanins are responsible for absorbing and protecting the skin from UVA and UVB radiation. UV radiation also stimulates excessive melanin production, which leads to discolouration known as hyperpigmentation, most often appearing as patches of skin darker than the surrounding area. For this reason, UV filters and tyrosinase inhibitors are among the most commonly used ingredients in products for the treatment of hyperpigmentation (7, 8).
The role of arbutin lies in its ability to inhibit tyrosinase, the key enzyme responsible for the formation of melanin. Thus, arbutin helps reduce the production of skin pigment, making it effective in addressing hyperpigmentation, including melasma, age spots and uneven skin tone (7, 8).
In a study by Sugimoto et al. (2004) the inhibitory effect of α-arbutin on melanin biosynthesis was investigated in cultured human melanoma cells and a three-dimensional human skin model. The studies showed that α-arbutin at a moderate dose (0.25%) significantly reduced tyrosinase activity without cytotoxic effects, increased superoxide dismutase (SOD) activity in the skin and reduced the production of free radicals, which helped to alleviate pigmentation disorders. While it did not affect the growth of cultured human melanoma cells, it notably reduced melanin synthesis, indicating its safety and efficacy in the treatment of hyperpigmentation disorders (9).
Anti-ageing and antioxidant properties
One of the main factors significantly contributing to internal ageing is oxidative stress, which is caused by the accumulation of oxygen-containing free radicals, also known as reactive oxygen species (ROS). These unstable molecules are produced both by natural metabolic processes and by external factors such as UV radiation, environmental pollution and poor nutrition. ROS can cause significant damage to cells and cell components such as proteins and DNA, leading to accelerated ageing, and the development of various skin diseases such as cancer and inflammatory diseases, as well as cardiovascular and neurodegenerative diseases and diabetes (10).
This is where antioxidants play a crucial role. Antioxidants are molecules that react with free radicals and thus help to prevent or repair oxidative damage at the cellular level. By reducing oxidative stress, antioxidants protect the skin and the body. In skincare, antioxidant ingredients such as arbutin are considered key components of anti-ageing formulations. They help protect the skin from free radical-induced damage, reduce oxidative stress and support overall skin health, contributing to a more youthful and resilient complexion (10).
What is the role of arbutin? Arbutin reacts with ROS, such as hydroxyl radicals, and activates the Nrf2-ARE signalling pathway, increasing cellular antioxidant capacity. It also inhibits ROS-mediated signalling in melanocytes, thereby preventing hyperpigmentation. Additionally, it increases intracellular thiol pools, which boost pheomelanin synthesis, while reducing eumelanin production through the formation of DOPA-thiol conjugates. The mechanisms based on antioxidant activity and tyrosinase inhibition complement each other, and act synergistically to reduce the synthesis of melanin (5, 8).
The antioxidant properties have been confirmed by various in vitro tests such as free radical scavenging activity with DPPH and ABTS assays (11). It was also found out that arbutin can be used as a cytoprotective agent against toxic substances such as tert-butyl hydroperoxide (t-BHP) (12). The protective effect was also confirmed on erythrocytes and skin fibroblasts (11).
Anti-inflammatory effects
Arbutin has been shown to inhibit pro-inflammatory cytokines such as IL-1β and TNF-α, efficiently reducing inflammation and promoting skin healing. The anti-inflammatory properties of arbutin have also been confirmed in in vitro tests with gastric ulcer cell lines and in vivo studies on rats (8).
Anti-inflammatory activity is the basis for the common use of arbutin in cosmetic products for sensitive skin, where it helps soothe redness and irritation. In addition, arbutin is a common ingredient in formulations targeting post-inflammatory hyperpigmentation, and is often used in sunscreens to prevent UV-induced pigmentation and associated inflammation.
COMPARATIVE INSIGHTS: ARBUTIN VS. HYDROQUINONE
The active form of arbutin is hydroquinone, which is produced by the hydrolysis of the arbutin glycoside. Both arbutin and hydroquinone inhibit the enzyme tyrosinase, and thus reduce melanin production. Hydroquinone has historically been used for skin lightening, in concentrations of 2 to 5% for conditions such as melasma, hyperpigmentation and sunspots (5).
Hydroquinone can suppress the activity of tyrosinase by up to 90%, significantly reducing melanin production (13). However, its use has been associated with serious side effects such as damage to cell membranes, glutathione depletion and suppression of DNA/RNA synthesis. It can also cause skin irritation and potentially trigger inflammation and post-inflammatory hyperpigmentation (8).
Due to safety concerns, including potential carcinogenicity, the use of hydroquinone was banned in 2001 by an EU regulation for cosmetic and OTC (over-the-counter) products (5). However, hydroquinone is still available by prescription in the EU for medical dermatological purposes, particularly for the treatment of hyperpigmentation disorders.
The United States has also placed restrictions on OTC hydroquinone skin-lightening products and hydroquinone is mainly available by prescription for dermatological use. While it may still be present in small amounts in certain industrial or cosmetic products, such as hair bleaches and nail adhesives, these are not its primary uses (8).
In contrast, hydroquinone continues to be widely used in many Asian countries, where it is still commonly prescribed by physicians, as well as used as a cosmetic treatment, particularly for skin-lightening and hyperpigmentation.
As reported in the literature, comparative studies between arbutin and hydroquinone demonstrate that arbutin possesses antioxidant activity that is at least equivalent, and in some cases superior, to hydroquinone. Furthermore, its antioxidant effect appears to be more prolonged than that of hydroquinone (11).
In conclusion, the main advantage of arbutin over hydroquinone is its safety. Even at high concentrations (e.g. 10% aqueous solution), arbutin does not cause significant side effects and is neither mutagenic nor carcinogenic. Nevertheless, excessive concentrations can still cause skin irritation or hyperpigmentation in some cases (8).
FORMULATION GUIDELINES
Optimal use in cosmetics
Arbutin can be incorporated into various cosmetic products. Its primary applications focus on reducing hyperpigmentation, freckles and melasma, while also addressing sensitive skin and anti-ageing treatments (6, 14).
α-Arbutin usually appears as a white or light-yellow powder. It is soluble in water, methanol and ethanol. For optimal processing, α-arbutin should be incorporated into the water phase of a formulation or added during the final stages at temperatures below 70 °C, ideally around 40 °C. This ensures the preservation of its active structure and stability (6, 14).
Although α-arbutin effectively inhibits human tyrosinase activity, its high hydrophilicity (log P of 1.49) limits its ability to penetrate the hydrophobic stratum corneum and reach the basal layer, where melanocytes are located (15). This characteristic poses a major challenge for the optimal delivery and dermal penetration of the active ingredient. Additionally, its stability in buffered aqueous solutions is pH-dependent (14). To maintain its integrity in cosmetic formulations, it is advisable to keep the final pH between 5 and 7. Extreme acidity or alkalinity can cause the hydrolysis of arbutin into a sugar unit and hydroquinone, thus reducing its effectiveness. If these guidelines are followed, α-arbutin can be effectively utilised to create stable, effective and safe skincare products (6, 14).
After purchasing the raw material from the supplier, it should be stored at 10–25 °C in tightly sealed containers in a dry, light-protected environment. Under these conditions, arbutin remains stable for at least 24 months. After opening the original packaging, it is strongly recommended to use the product immediately (6, 14).
Despite these precautions, arbutin may partially hydrolyse to hydroquinone during the processing of raw materials, manufacturing and storage of a product, or even during use. For this reason, ensuring high purity of the raw material is crucial, whether it is synthesised chemically, plant-derived or produced biotechnologically. Appropriate formulation strategies are also important to maintain stability, as contact with microorganisms or UV radiation during storage and use can further promote the formation of hydroquinone (5).
Concentrations and safety
The recommended concentration of arbutin in formulations is between 2.0 and 7.0% to achieve noticeable skin-whitening effects. According to the SCCS, α-arbutin is safe in face creams at concentrations up to 2% and in body lotions at concentrations of up to 0.5%, even when used together. Similarly, β-arbutin is considered safe in face creams at concentrations up to 7%. In formulations containing α- or β-arbutin, the hydroquinone content should be kept as low as possible and limited to unavoidable trace amounts (16).
Scientific studies show that arbutin has no toxic effects on melanocytes, making it safe for use in cosmetic formulations when applied at appropriate concentrations. However, excessive use or high concentrations can lead to side effects, such as skin irritation (16). Given the advantages of α-arbutin over other skin-lightening ingredients, efforts to enhance its skin penetration and permeability are essential for maximising its effectiveness.
Combining arbutin with other cosmetically active ingredients that work synergistically, such as L-ascorbic acid, aloesin, linderanolide B, kojic acid, capsaicin, niacinamide or tranexamic acid, can significantly increase skin lightening (5). Therefore, instead of using arbutin alone, it is more effective to combine it with active ingredients that have different mechanisms of action (5).
CONCLUSION
Arbutin continues to be a standout ingredient in the skincare industry, valued for its natural origin, proven effectiveness and compatibility with sustainable practises. With the use of α-arbutin, we can address pigmentation, skin ageing and overall skin health. As consumer demand for environmentally conscious and active skincare solutions grows, arbutin’s role in creating safer and more effective cosmetics will continue to grow further, solidifying its place as a trusted choice for radiant and healthy skin.
Ana Marolt, B. Sc. Cosmetic Science, M. Ind. Pharm.
Modern CosmEthics, Velenje, Slovenia
ana@cosmethicallyactive.com
References
Please click on the references below for more information.
12. Seyfizadeh N et al. Is arbutin an effective antioxidant for the discount of oxidative and nitrosative stress in Hep-G2 cells exposed to tert-butyl hydroperoxide? Bratisl Lek Listy. 2019; 120(8):569-75.
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