Alpha Arbutin

Arbutin is a skin-lightening agent ad also a glycosylated hydroquinone extracted from the bearberry plant in the genus Arctostaphylos. It inhibits tyrosinase and thus prevents formation of melanin.

Melanin is the main substance responsible for human skin color. It is a dark polymers generated by the body through the process named melanogenesis. Variation of skin color among individuals is due to the variation of melanin content in the skin. Skin with little or no melanin is almost white. Other factors influence skin color in a lesser degree including the amount of blood in blood vessels, skin thickness and carotenoids in skin.

Skin whitening agents work by reducing the amount of melanin in the skin. There are several possible mechanism of actions including:

  • Inhibition of the tyrosinase activity

where, catalytic action of tyrosinase is inhibited (slowed or nearly stopped) by skin whitening agent.

  • Inhibition of the expression or activation of tyroxinase

The anti-melanogenic agent causes that less troxinase is generated or that tyrosinase is not activated to its functional form.

  • Scavenging of the intermediate products of melanin synthesis.
  • Preventing the transfer of melanosomes to keratinocytes.
  • Directly destroy existing melanin.
  • Destroying melanocytes


Melanin synthesis process

Melanin in synthesized in melanosomes which are organelles produced in melanocytes. Melanocytes are cells dedicated to this function that are present in the skin, hair follicles, and other structures of the body. The synthesis of melanin (also called “melanogenesis” and “melanization”) involves a chain of enzyme-catalyzed chemical reactions and non-enzyme-catalyzed reactions.


The main precursor to melanin is L-tyroxine. The first step of melanogenesis is the conversion of L-tyrosine to L-Dopa. This is the first and rate-limiting step and is catalyzed by the enzyme tyrosinase (TYR). Other enzymes involved in the synthesis include tyrosinase-related protein 1(TRP1) and tyrosinase-related protein2 (TRP2). TRP2 is also known as “dopachrome tautomerase” (DCT). L-tyrosine is taken by the melanocytes from the intercellular medium, then transported to the melanosomes. L-tyrosine is also synthesized within the melanocytes from L-phenylalanine by the enzyme phenylalanine hydroxylase (PAH). Melanosomes are transferred to keratinocytes (the most abundant cell type in the skin). Most of the melanin of skin is found in keratinocytes. Additionally, melanocytes interact with keratinocytes through chemical signaling.

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