نبذة مختصرة : Melanogenesis is a process catalyzed by tyrosinase enzyme leading to synthesis of two types of pigment in the skin: black-brown eumelanin and red-yellow pheomelanin. Pheomelanin is synthesized in the second stage of melanosome maturation, while eumelanin-synthesizing melanosomes are inactive. The black-brown pigment is produced in the third stage of melanosome development. The last, fourth stage of melanosome maturation is characterized by low tyrosinase activity, which reflects the low pigment production in the skin. The process of skin pigment production (melanogenesis) is mainly regulated by solar radiation, hormones and other endo- and exogenous factors. Over- stimulated melanogenesis leads to unsightly hyperpigmentation of the skin. Some substances used in cosmetics have the ability to regulate melanogenesis and lower melanin levels. The active ingredients on active melanocytes include: azelaic acid and azeoglycin, ferulic acid, ascorbic acid, kojic acid, tranexamic acid, extract of common daisy, licorice root extract, soybean extract, milk thistle extract, white mulberry extract, turmeric and bitter melon leaves extract, aloe extract as well as sericin, hesperidin and niacinamide. The literature also emphasizes the possibility of influencing inactive melanocytes, such ingredients include vitamin A and its derivatives, hydroquinone, arbutin, Chinese tea and ashwagandha. Each of the described active ingredients is characterized by a different activity and partially different mechanism of action, which is based mainly on the inhibition of the activation of enzymes involved in melanogenesis (tyrosine and TRP-1 and TRP-2 proteins) mainly by: blocking the expression of MITF and binding to copper ions in the active site for tyrosinase. Active substances with a brightening effect applied externally to the skin are effective in hyperpigmentation therapies in which there is an increased amount of eumelanin in melanosomes, an increased activity of melanocytes and an increased transfer of melanin to keratinocytes. The aim of the study was a literature review of the most frequently described active ingredients of natural origin with properties that lighten skin discoloration, paying attention to the potential effectiveness of selected active substances and their mechanism of action with reference to the melanogenesis process.
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