Arbutin

Absorption

Arbutin was found to be extensively absorbed from the gastrointestinal tract where it is primarily converted to hydroquinone .

Toxicity

In an acute oral toxicity study, the LD50-value for β-arbutin is 9804 mg/kg bw for the mouse and 8715 mg/kg bw for the rat . Dermal LD50 value in rat and mouse was reported to be greater than 928 mg/kg bw, according to an acute dermal toxicity study . Extremely high doses may cause ringing in the ears, shortness of breath, convulsions, collapse, vomiting and delirium . Nausea and vomiting were seen individuals with sensitive stomachs following oral ingestion of 15 g of dried uva ursi leaves that contain arbutin .

Description

Arbutin is a β-D-glucopyranoside HQ derivative and a plant-derived compound found in the dried leaves of several plant species, including blueberry, cranberry, bearberry, and pear trees. It suppresses tyrosinase activity without altering RNA expression.

The Uses of Arbutin

Arbutin is a glycosylated hydroquinone extracted from bearberry plant. Arbutin is a known inhibitor of tyrosinase, which in turn prevents the formation of melanin. Arbutin is often used as a skin-ligh tening agent in cosmetic products.

Indications

Indicated for over-the-counter use for epidermal hyperpigmentation in various skin conditions, such as melasma, freckles, and senile lentigines.

What are the applications of Application

Arbutin is an inhibitor of Tyrosinase

Background

Extracted from the dried leaves of bearberry plant in the genus Arctostaphylos and other plants commonly in the Ericaceae family, arbutin is a beta-D-glucopyranoside of Hydroquinone. It is found in foods, over-the-counter drugs, and herbal dietary supplements . Most commonly, it is an active ingredient in skincare and cosmetic products as a skin-lightening agent for the prevention of melanin formation in various skin conditions that involve cutaneous hyperpigmentation or hyperactive melanocyte function . It has also been used as an anti-infective for the urinary system as well as a diuretic . Arbutin is available in both natural and synthetic forms; it can be synthesized from acetobromglucose and Hydroquinone . Arbutin is a competitive inhibitor of tyrosinase (E.C.1.14.18.1) in melanocytes , and the inhibition of melanin synthesis at non-toxic concentrations was observed in vitro. Arbutin was shown to be less cytotoxic to melanocytes in culture compared to Hydroquinone .

Pharmacokinetics

At non-toxic concentrations, arbutin inhibited the activity of tyrosinase in cultured human keratinocytes, while having minimal effect on the expression of tyrosinase mRNA or the synthesis of the enzyme . α-Arbutin produced a concentration-dependent inhibition of melanin synthesis of human melanoma cells, HMV-II . No inhibitory effect on HMV-II cell growth was seen at concentrations lower than 1.0 mM. At concentrations of 0.5 mM of arbutin, tyrosinase activity was reduced to 60% of that in non-treated cells . The addition of arbutin blocked and inhibited α-MSH-stimulated melanogenesis in B16 melanoma cells, brownish guinea pig, and human skin tissue . In a pilot study of healthy male adults exposed to UV B irradiation, topical administration of arbutin inhibited UV-induced nuclear factor-kappaB activation in human keratinocytes . In mouse skin, arbutin counteracted oxidative stress induced by 12-O-tetradecanoylphorbol-13-acetate .

Metabolism

Arbutin is readily susceptible to hydrolysis in dilute acids to yield D-glucose and hydroquinone. It is expected that orally administered arbutin is easily hydrolyzed to free hydroquinone molecules by stomach acid . Hydroquinone is further metabolized into the main metabolites, hydroquinone glucuronide and hydroquinone sulfate .