Arbutin

Arbutin is a plant-based phenolic compound that occurs naturally in multiple plant sources such as bearberry, cranberry, and lingonberry leaves, as well as pear tree leaves and marjoram.

In skincare it is used as an antioxidant, but with its own very specific applications – it is one of the few proven compounds that actually treat pigmentation issues.

Arbutin is a very simple phenolic compound that is usually present in nature in the form of glycoside (a.k.a. bound to a sugar molecule), making it a bit more stable. When applied to the skin, the sugar molecule snaps off and the arbutin changes into its active form, a molecule called hydroquinone.

Hydroquinone is very reactive and, in skin cells, binds to the enzyme called tyrosinase and inhibits its action. Tyrosinase is the main enzyme responsible for the creation of the dark skin pigment called melanin, and so applying arbutin cream to the skin has an anti-pigmentation effect which can be used as a treatment of already existing dark spots, or as a prevention.

Of course, huge amounts of arbutin and hydroquinone can be irritating to sensitive and inflammation-prone skin, and so you shouldn't overdo it with arbutin-containing products.

As a fun fact, in general healthcare, herbs containing arbutin are used in the treatment of urinary tract infections.