The skin system has a very powerful endogenous antioxidant defense system, including vitamin E, superoxide dismutase, glutathione peroxide, etc., which can effectively combat oxidative stress caused by ultraviolet rays.
How is black skin formed?
Melanin production pathway
Melanin is a biological pigment synthesized in melanocytes and is a protective pigment for the skin. Its synthesis pathway in the body is: tyrosinase catalyzes tyrosine to form dopa, and dopa dehydrogenation to form dopaquinone, rearrangement 5,6-quinoneindole is formed, and finally combined with structural proteins in the melanin body to form melanin.
Tyrosinase, as a key enzyme for melanin synthesis in organisms, is also the rate-limiting enzyme for melanin synthesis, forming skin protective melanin. Tyrosinase activity determines the content of melanin, and its abnormal expression can lead to pigment-related diseases. Therefore, tyrosinase inhibitors are expected to be used in pigmented lesions and depigmented lesions.
Studies have found that the proliferation and melanin synthesis of melanocytes are also affected by the regulation of genes, hormones, cytokines and ultraviolet rays.
Sun tanning is one of the ultraviolet rays that make you darken. Ultraviolet rays can directly stimulate melanocytes to increase the dendrites of melanocytes, increase tyrosinase activity, and increase melanin production.
So why does Mother Nature give melanin to humans? Because it looks good?
Because melanin can convert ultraviolet rays into heat, thereby reducing the occurrence of mutations. So black is not without benefits at all.
But everything has a certain amount. Excessive exposure to the sun or other sources of ultraviolet rays will destroy the skin’s antioxidant capacity, and even affect the melanocytes to synthesize melanin particles, leading to pigment-related diseases.