Name of the species of common spots
The synthesis of melanin must involve tyrosine, tyrosinase and oxygen;
Synthesis and secretion of skin melanin
0 1. Melanin is hydroxylated from phenylalanine to tyrosine and oxidized to dopaquinone under the catalysis of tyrosinase.
02. dopaquinone is automatically oxidized to produce dopa and dopa pigment, which is also the substrate of tyrosinase. After catalysis, dopaquinone is generated again, and the reaction products of dopa pigment, 5,6-dihydroxy indole and 5,6-dihydroxy indole carboxylic acid, undergo a series of oxidation reactions to generate eumelanin, which is the main component of skin pigment.
03. In the presence of cysteine or glutathione, dopaquinone will be converted into cysteinyl dopa or glutamine dopa, and finally melanin will be generated.
Influencing factors of melanin synthesis
There are many factors that affect melanin synthesis in life, such as oxygen free radicals, ultraviolet rays and so on.
Oxygen free radicals are produced by human metabolism or ultraviolet radiation. They can not only attack macromolecules, such as protein, nucleic acids and unsaturated fatty acids, resulting in skin loss of elasticity and DNA damage, but also promote melanin synthesis and pigmentation by stimulating the secretion of melanin activating factors, such as PGE2 and α-MSH.
There are two main types of ultraviolet rays: UVA and UVB. Among them, UVA can make keratinocytes and melanocytes in the skin produce reactive oxygen species and nitric oxide, and the production of oxygen free radicals can promote the expression of TYR, increase TYR activity and melanin production. UVB can cause DNA damage, stimulate the differentiation of melanocytes and activate the transcription of pigment-related enzymes, such as TYR, thus increasing TYR activity and stimulating melanin synthesis.
Melanin inhibition method
According to the synthesis and influencing factors of melanin, there are generally the following methods to reduce melanin production:
Biosynthesis of melanin
Tyrosinase inhibitor & gt& gt& gt
Tyrosinase plays an important role in melanin biosynthesis. It is the main rate-limiting enzyme for the conversion of tyrosine and dopa into melanin, and its over-expression is an important reason for pigmentation. Therefore, the inhibitory effect of melanin is mostly concentrated on tyrosinase, and there are three main ways:
0 1. Inhibit the catalytic activity of tyrosinase: kojic acid, polyphenols, resveratrol derivatives and cinnamic acid derivatives can inhibit the activity of tyrosinase and block the formation of important intermediate products in the process of melanin production;
02. Promote tyrosinase degradation: For example, Eupolyphaga Seu Steleophaga can degrade tyrosinase through proteasome pathway, and isoparaffin triterpenes can degrade tyrosinase through lysosome pathway;
03. Inhibition of tyrosinase expression: MITF gene plays an important regulatory role in the transcription and translation of tyrosinase, so MITF gene can be used to inhibit the expression of tyrosinase gene.
& gt& gt& gt scavenging free radicals
Ultraviolet rays or self-metabolism can produce free radicals that can increase melanin synthesis ability, so blocking or eliminating free radicals can inhibit the formation of melanin, and common vitamins C and E can eliminate free radicals, thus inhibiting melanin synthesis.