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Melanin: Synthesis, Medical Issues & Toxicity

Have you heard about melanin, that pigment that gives color to eyes or skin? Well, if you didn`t, you are about to find out more about it in the following article.

What Is Melanin

What Is Melanin?

Melanin is a natural substance that offer color to the eyes, skin and hair, an aspect that is common for most people. However, there are a series of interesting things related to melanin, such as its role, where and how it`s synthesized, but also what imbalances are associated with it.

Important Aspects

In simple words, melanin (also known as the skin pigment) colors the eyes (iris), skin and hair, and protects the skin from the sun, being the main determinant in the skin`s color; the persons with darker skin have an increased level of melanin compared with those with lighter skin. Melanin is created by some cells known as melanocytes, which intensify its production as a response to sun exposure. Freckles, which occur in people of all ethnicities, represent small and concentrated parts with an increased production of melanin. Although not many people know this, melanin is produced by the pineal gland and it`s also present in the striated vascularization of the internal ear, but also in the brain (substantia nigra, medulla and locus coeruleus), in the reticulated area of the adrenal gland, in thymus, in the thyroid gland and pituitary gland. Additionally, this substance is localized in all the main functional areas, including the heart, liver, arteries, muscles and gastrointestinal tract – practically all the body`s organs.

Melanin is formed in the metabolizing process of an amino acid known a tyrosine, at the skin`s surface being created by melanocyte. However, in some cases (such it`s occurred in albinism), melanin misses, this issues occurring not only in human beings, but also in animals or plants. This hormone represents one of the great variables of the human traits and a lot of polygens are involved.

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The groups of population were a long time ago classified depending on the skin color: black (nubian), white (caucasians), yellow (oriental) and red (aboriginal). Still, it should be known that the skin color depends on a lot of factor and not only melanin. Of course, first of all it`s about the amount of melanin from the skin external layers which prevent like a filter the damage of the deeper layers of the skin caused by UV rays. Therefore, in some areas of Africa, Australia or India, the melanin deposits from the skin are significant because the people were exposed for longer generations to intense sunlight. Also, it plays an essential role in the skin thickening, thus those with darker skin have thicker layers of melanin. When an individual adapts to the intensity of sunlight, the skin becomes darker in color.

Why Is Melanin Important?

This biological pigment (biocrom) has a role that wasn`t completely elucidated by now. Melanin is obvious in the darker moles of people or in black dermal melanocytes of most black people, and sometimes has the brown color in the case of the well known freckles. Melanin confers a lot of benefits that are little known to people besides their protection to UV rays. However, you should know that people with darker skin aren`t completely protected by sunlight, but rather they tolerate the sun exposure better, without gaining sunburns (those with lighter skin present sunburns only after a few minutes). Keep in mind that skin cancer is related to sun exposure (as well as cataracts) and to a reduced level of pigment. However, melanin also constitutes a mechanism of absorption on sunlight, being essential for cold-blooded animals (to stabilize the body temperature), but also for visual acuity, minimizing the number of rays that penetrate the eyes. Last but not least, due to molecular structure, it offers resistance to abrasion.

A recent research suggests even that melanin has other roles besides the photoprotectant one, meaning the ligation of metal ions by carboxyl and phenolic hydroxyl groups, in a lot of situations even extremely effective, which consequently may serve for capturing toxic metal ions to protect the rest of the cells (it was noticed in this regard in the Parkinson disease that losing neuromelanin is accompanied by increased levels of iron in the brain).

Synthesis

There are a few stages involved in melanin biosynthesis, the first being known as L-3,4-melanindihydroxyphenylalanine tyrosinase catalysis, lack of tyrosine might lead to albinism. These melanosomes leave melanocytes and pass into other cells from the epidermis; the deposits of melanin are brown and determine the skin pigment depending on the melanoma distribution. Melanocytes follow the instruction of DNA and create enzymes that produce melanin and tyrosine. Insides melanosomes, enzymes act as catalysts and begin a few chemical reactions to convert tyrosine into the 2 types of human melanin: eumelanin and feomelanin. Once it`s filled with melanin, the melanosome sends it to the keratinocytes. Once carried, the pigments will determine the skin, hair and eye color. When hair follicle melanocytes don`t produce sufficient melanin, the color might vary from white to yellow to brown, without having any impact on the person`s health. Inside the keratinocytes, melanosomes respond to the sun`s rays covering their nucleus and protecting the DNA. Inside the keratinocytes, melanosomes respond to the rays of the sun covering their nucleus as well as protecting the DNA. Although UV rays may damage it, but melanin absorbs these rays.

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Here`s in a concrete way where are the types of melanin mentioned located:

  • eumelanin in skin, hair and dark areas around the nipples;
  • feomelanin in hair and skin;
  • neuromelanin in different areas of the brain.

Medical Issues

The most common problem that is associated with melanin is albinism; in the case of people affected by albinism there aren`t enough melanosomes to fight against the harmful rays, leaving the skin vulnerable and increasing the risk of sunburn and skin cancer. This illness can exist in several degrees, involving the hair, skin, eyes or all of them (when talking about the eyes, it`s affected the sight as well) In some situations, albinism is associated with an increased rate of mortality. According to some studies, albinism may cause loss of hearing. When Parkinson is concerned, it was noticed a decreased level of neuromelanin in locus coeruleus and substantia nigra. Increased levels of eumelanin can also be harmful, causing among others an increased risk of vitamin D deficiency. Nicotine has some kind of an affinity for melanin-containing tissues (because of its function in its synthesis), therefore it was suggest that it may contribute to the persistence of smoking addiction, respectively in reducing the percentage of smoking cessation in dark skin. – Click here!

There are cases when melanin occurs pathologically in the form of malignant melanoma, a cancerous cell that is composed of melanin pigmented cells. Specialty literature also the industrial melanism which is involved in the skin “discoloration” of animals because of the evolution of the species which occurred in less than 100 years.

Toxicity

Melanin presents a toxic potential as well, therefore by consuming unhealthy foods or by eating too much, the connection with solar energy may be blocked (when it cannot reach melanin, there are a series of diseases that occur). Persons with toxic levels will most likely behave in a primitive, barbaric manner. It was noticed that vitamin B helps maintaining its purity, along with good habits when consuming food. This particular substance usually acts like a superconductor (similar to the battery of the car) and is always charged when it becomes expose to sunlight, color or sound, the human body being able to create it when needing to survive, constantly recharging every time it`s stimulated. Persons with dark skin are, thus, sensitive to certain radio wave types or environmental issues, so remember that your lifestyle may infuse this essential substance in your organism.

Image courtesy of quora.com
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