Melanotan 1

Melanotan

Note: this article describes both melanotan and melanotan II: although their names are similar, they have different chemical and biological properties.

Melanotan 1 and melanotan II are both analogs of the peptide hormone alpha-melanocyte stimulating hormone (α-MSH) that have been shown to induce skin tanning in preliminary studies and clinical trials. Melanotan II has the additional effect of increasing libido. Derivatives of both peptides are in development by pharmaceutical companies, but as of 2008 no melanotan I or II based compound has been approved for use by drug regulatory bodies. Unlicensed and untested melanotan products are sold through the Internet however, regulatory bodies have warned consumers they may be unsafe and ineffective.

Historical development

Both peptides were identified at the University of Arizona. Researchers there knew that one of the best defenses against skin cancer was a natural tan which has been slowly developed over weeks. They hypothesized that an effective way to reduce skin cancer rates in people would be to induce the body's natural tanning system to produce a protective tan prior to UV exposure. The body's naturally occurring hormone alpha-melanocyte stimulating hormone (α-MSH) causes melanogenesis, a process by which the skin's tanning cells (melanocytes) produce the skin's tanning pigment (melanin). With that knowledge they tested to see if administering this hormone to the body directly could be an effective method to cause sunless tanning. What they found was that while it appeared to work, natural alpha-MSH had too short a half life in the body to be practical as a therapeutic drug. So they decided to find a more potent and stable alternative, one that would be more practical.

After synthesizing and screening hundreds of molecules, the researchers headed by Dr. Victor Hruby, found a peptide that after trials and testing seemed to be approximately 1,000 times more potent than natural α-MSH. They dubbed this new peptide Melanotan. Since their discovery, numerous studies dating back to the mid-1980s have shown no obvious toxic effects of the Melanotan peptides (then known by their scientific names [Nle4, D-Phe7]-α-MSH and Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2). The scientists hoped to use Melanotan as a drug to combat melanoma by stimulating the body's natural tanning mechanism to create a tan without first needing exposure to harmful levels of UV radiation . This in turn, they hypothesized, could reduce the potential for skin damage that can eventually lead to skin cancer.

The scientists licensed their patented peptides, via a technology transfer company, to a number of biotechnology companies who intend to develop them into drugs.

Peptide properties

Melanotan 1

Melanotan 1 has the amino acid sequence Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2 or [Nle4, D-Phe7]-alpha-MSH.

Melanotan is currently being tested and developed under the International Nonproprietary Name afamelanotide (formerly the proprietary CUV1647) by the Australian company Clinuvel Pharmaceuticals, for a series of skin related diseases including polymorphous light eruption (PMLE) and actinic keratosis (AK).

A Phase II clinical human trial study conducted in 2003 at the University of Sydney demonstrated in a group of eighty volunteers that Melanotan caused a highly significant increase in skin-melanin. It found fairer-skin people (Fitzpatrick Types I/II, those who never tan and only burn and those who can tan in a limited fashion) recorded increases in melanin of up to 100% in some areas and that sunburn injury was reduced by more than 50% in fair skinned volunteers.

Melanotan II

Melanotan II has tanning and aphrodisiac properties.

It is a cyclic lactam analog of alpha-MSH with the amino acid sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2.

A pilot Phase I clinical trial conducted on three males by the College of Medicine, Pharmacology Department, University of Arizona in Tucson, Arizona published in 1996 demonstrated that, "Melanotan II has tanning activity in humans given only 5 low doses every other day by subcutaneous injection." The side effects reported were mild nausea and a "stretching and yawning complex" that correlated with spontaneous penile erections.

Bremelanotide

Palatin Technologies developed another hormone originally targeted towards sexual dysfunction based upon melanotan II called bremelanotide (formerly PT-141). Bremelanotide is a metabolite of melanotan II that lacks the C-terminal amide function. In 2008, development for sexual dysfunction was discontinued after concerns were raised by the U.S. Food and Drug Administration (FDA) about the adverse side effect of increased blood pressure found in Phase II clinical trials, but the company announced plans to develop it as a treatment for hemorrhagic shock instead.

Drug agency warnings

In 2007, the FDA issued a warning to an American vendor illegally marketing melanotan II on the internet as a drug that prevents skin cancer and assists tanning. The FDA has not licensed melanotan II, and explained: "There is no evidence that the product is generally recognized as safe and effective [GRAS/E] for its labeled uses."

On August 8, 2008 the Danish Medicines Agency (DMA) issued a warning against the usage of Melanotan purchased on the internet, noting that claims that imply that it has an, "effect" for protection against skin cancer, "has not been documented". The DMA further warned that Melanotan has not undergone tests for its effect and possible side effects, and that it is not licensed for usage in the EU or the USA.

References

External links

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