Skin whitening, also known as lightening, brightening, depigmentation, and bleaching is the use of substances, mixtures, or physical treatments to lighten skin color. Skin whitening treatments work by reducing the skin’s melanin content. Many agents have been shown to be effective in skin whitening. Some agents have beneficial side effects, including supplying antioxidants or nutrients or reducing the risk of some types of cancer. Other agents are a significant risk to health, such as mercury-based methods.
Melanogenesis inhibitors have been discovered and developed using several methods. One way is through the screening of synthetic chemical libraries. This method occasionally uses high throughput screening. Another way works by screening of plant extracts by computational search with off-label use of previously known drugs or exploration of structural analogues of previously known tyrosinase inhibitors.
These inhibitors are based on knowledge in varying degrees of their structure-activity relationship. The development and discovery of melanogenesis inhibitors illustrates many of the methods used in drug design. Some of the most potent competitive reversible tyrosinase inhibitors are synthetic compounds with a potency a hundreds times more than that of kojic acid.
Melanin is the main substance responsible for the color of the skin. Melanin is a class of dark polymers generated by the body through the process of melanogenesis. Among the melanin pigmenting the skin and hair, two types can be distinguished based on its chemical composition and biological route of synthesis: the black and brown eumelanin and the red and yellow pheomelanin. The variation of skin color among individuals is mostly caused by variation of the content of melanin in the skin.