Melatonin and melanin are two substances found in living organisms. Most of the time, people confuse melanin with melatonin due to the similar pronunciation. However, these are two different molecules associated with completely different functions in the human body.
Key Areas Covered
What is Melanin
Melanin is an indolic polymer synthesized using the amino acid Tyrosine, and it is the major pigment of the skin, hair, and pigmented tissue underlying the iris of the eye and the wall beyond the inner ear (stria vascularis). There are three types of melanin, namely eumelanin (common type), pheomelanin, and neuromelanin. Melanin is biosynthesized and stored in cells called melanocytes, the origin of which is the neural crest of the embryo, and then migrates to many other sites of the vertebrate body. Melanocytes are mainly found in the basal layer of the human skin (epidermis and underlying dermis) and give the skin its color. Melanin is stored inside granules in the cytoplasm of the melanocytes and appears as dark blobs.
The major function of melanin (and melanocytes) is to provide protection from ultraviolet (UV) radiation for the skin and underlying organs. The ability of the pigment to absorb UV radiation is 99%. Therefore, people with darker skin color are less prone to skin cancer than people with lighter skin color.
What is Melatonin
As mentioned earlier, melatonin (N-acetyl-5-methoxytryptamine) is a hormone that is secreted from the pineal gland of the human (and animal) brain. It is biosynthesized using the amino acid Tryptophan as the precursor. Melatonin was first discovered after feeding cow pineal gland extract to tadpoles, and the skin color of tadpoles was brightened as a result of contracting dark melanophores. The main functions of melatonin are regulating the sleeping and waking cycle (circadian rhythm), blood pressure, and seasonal breeding in animals. In plants, it regulates responses to photoperiod, defensive strategies during harsh environmental conditions, and as an antioxidant.
Moreover, melatonin is prescribed as a drug for insomnia. Treatment may be either long-term or short-term, depending on the condition the patient has. In addition, other useful properties of melatonin include reduction of anxiety, preventive treatment for migraines, evidence to cure cancers, protection of gallbladder, protection from radiation, vivid dreaming, etc.
Difference Between Melanin and Melatonin
Melatonin is a hormone, while melanin is a pigment.
Moreover, melatonin uses tryptophan as the precursor, whereas melanin uses tyrosine.
Melatonin is a small molecule, whereas melanin is a polymer.
Melatonin is synthesized in different tissues of the body, but melanin is synthesized in melanocytes.
Storage and release
While melatonin is stored and released from the pineal gland to the bloodstream, melanin is stored in melanocytes, and no such release occurs.
Melatonin is responsible for circadian rhythm, while melanin is responsible for protection from UV radiation.
The main difference between melanin and melatonin is that melanin is a pigment responsible for skin color, whereas melatonin is a hormone responsible for the biological clock of the human body.