Melanotan II is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-05-31. Where a claim depends on a specific study, the study is described rather than over-claimed.
The compound was developed in the late 1980s and 1990s by academic researchers investigating photoprotection. The rationale held that stimulating melanin production might reduce ultraviolet damage to skin and lower skin cancer risk. Early work examined receptor binding, pigment response, and short-term tolerability in small studies. That program did not produce an approved drug, and formal development stalled after early-phase trials. Whether induced pigmentation confers meaningful photoprotection remains an open question.
Outside regulated medicine, melanotan II circulates through online vendors as a research chemical, often marketed for tanning. Products sold this way vary widely in purity, concentration, and labeling accuracy, and independent testing has documented discrepancies. Published reports describe both pigment effects and adverse reactions, including nausea, flushing, and darkening of existing moles. Long-term safety data are sparse, and no large controlled trial has established a risk profile. Questions about cumulative effects on melanocytes remain unresolved in the literature.
Melanotan II is a synthetic peptide analog modeled on alpha-melanocyte-stimulating hormone, a naturally occurring signaling peptide involved in pigmentation. Its structure is a cyclic heptapeptide containing two non-natural substitutions, norleucine at position four and D-phenylalanine at position seven. These modifications resist enzymatic breakdown and extend the molecule's activity relative to the native hormone. The compound binds melanocortin receptors and is studied mainly as a pharmacological tool rather than a therapeutic product. It has never received approval as a medicine in any major jurisdiction.
Melanotan-2, also written Melanotan II, is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, and the lactam bridge between the aspartate and lysine side chains constrains the peptide into a ring. This structural change increases receptor affinity and metabolic stability relative to the native hormone. The compound was created in the 1980s as a research tool for studying pigmentation biology.
Melanocytes are the pigment-producing cells of the skin, and they carry melanocortin-1 receptors on their surface. When the receptor is activated, cyclic adenosine monophosphate rises inside the cell and raises the activity of enzymes such as tyrosinase, which increases melanin output. Melanotan-2 binds melanocortin-1 receptors in vitro and in animal models, and this binding is generally described as the basis for the tanning effect. Other receptors account for different effects: melanocortin-4 receptors contribute to appetite and erectile signalling, while melanocortin-3 and melanocortin-5 receptors contribute to energy balance and exocrine function.
Early published reports described melanotan-2 as a tanning agent without sun protection, which means darkening is not the same as protection against ultraviolet radiation. Later studies explored the peptide in erectile dysfunction, hemorrhagic shock, and some skin conditions. No regulator in the United States or Europe has approved it for clinical use. Many products labelled melanotan-2 are sold without approval and their identity and purity are unverified. Its long-term safety in humans remains an open question.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Belongs to the melanocortin agonist family |
| Key substitutions | Nle4 and D-Phe7 | Improve resistance to enzymatic degradation |
| Molecular formula | C50H69N15O9 | Approximately 1024 g/mol |
| Regulatory status | Not approved as a medicine | Distributed as a research chemical |
| Common synonyms | Melanotan II, MT-II, MT-2 | Spelling varies across sources |
Melanotan II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
Receptor-binding studies classify melanotan II as a non-selective melanocortin agonist. It interacts with MC1R, MC3R, MC4R and MC5R, with reported affinities in the low nanomolar range and no strong subtype preference. Activation of MC1R on dermal melanocytes shifts pigment synthesis toward eumelanin, the dark polymer deposited in melanosomes and transferred to keratinocytes. Because the same peptide engages MC4R in the hypothalamus, it also appears in animal work on food intake and erectile response, which is why it is discussed in both pigment and metabolic research. Which receptor populations dominate after systemic exposure in humans is not fully established.
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
== U == Ultradian rhythm A recurrent biological cycle that occurs more than once in 24 hours, such as stages of sleep. In neuroscience, it refers to shorter rhythms regulating hormonal release, arousal, or sleep cycles. Unconditioned response In classical conditioning, an automatic, reflexive response to an unconditioned stimulus (e.g., salivation to food). Studied in behavioral neuroscience. Unconsciousness A state in which an individual is not aware of themselves or their surroundings. Can result from head injury, anesthesia, or metabolic dysfunction. Uncus A structure on the medial surface of the temporal lobe, part of the parahippocampal gyrus. It is involved in olfaction and is adjacent to the amygdala. Undershoot The hyperpolarizing phase following an action potential where membrane potential temporarily becomes more negative than resting potential. Unilateral neglect A neuropsychological condition following damage (typically to the right parietal lobe) in which patients ignore stimuli on one side of space. Unipolar depression A mood disorder characterized by persistent low mood, lack of energy, and anhedonia, without manic episodes. Associated with altered activity in the prefrontal cortex and limbic structures. Unipolar neuron A type of neuron with a single process extending from the cell body. Common in invertebrates and found in human sensory neurons. Upper motor neuron A neuron originating in the cerebral cortex or brainstem that transmits motor signals to lower motor neurons. Damage leads to spasticity, hyperreflexia, and weakness.
== Role in oligonucleotide formation == Phosphorimidazolides have been investigated for their mechanistic role in abiogenesis (the natural process by which life arose from non-living matter). Specifically, they have been proposed as the active electrophilic species which may have mediated the formation of inter-nucleotide phosphodiester bonds, thereby enabling template-directed oligonucleotide replication before the advent of enzymes. Phosphorimidazolides were originally proposed as mediators of this process by Leslie Orgel in 1968. Early studies showed that divalent metal cations such as Mg2+, Zn2+, and Pb2+ and a complementary template were required for the formation of short oligonucleotides, although nucleotides exhibited 5'-2' connectivity instead of 5'-3' connectivity of present-day life forms. It was also shown that Montmorillonite clay could provide a surface for phosphorimidazolide-mediated oligonucleotide formation with lengths of 20-50 bases. The research group of Jack W. Szostak has continued to investigate the role of phosphorimidazolides in pre-biotic nucleotide polymerization. The group has investigated a number of imidazole derivatives in the search for chemical moieties which provide longer oligonucleotides necessary for propagating genetic information. Significantly, they discovered that phosphorimidazolides promote template-directed oligonucleotide formation via imidazolium-bridged dinucleotide intermediates. John D.
The outermost layer of the gastrointestinal wall consists of several layers of connective tissue and is either of serosa (below the diaphragm) or adventitia above the diaphragm. Regions of the gastrointestinal tract within the peritoneum (called Intraperitoneal) are covered with serosa. This structure consists of connective tissue covered by a simple squamous epithelium, called the mesothelium, which reduces frictional forces during digestive movements. The intraperitoneal regions include most of the stomach, first part of the duodenum, all of the small intestine, caecum and appendix, transverse colon, sigmoid colon and rectum. In these sections of the gut there is clear boundary between the gut and the surrounding tissue. These parts of the tract have a mesentery. Regions of the gastrointestinal tract behind the peritoneum (called retroperitoneal) are covered with adventitia. They blend into the surrounding tissue and are fixed in position (for example, the retroperitoneal section of the duodenum usually passes through the transpyloric plane). The retroperitoneal regions include the oral cavity, esophagus, pylorus of the stomach, distal duodenum, ascending colon, descending colon and anal canal.
Sources: en.wikipedia.org
Sulfur deposits in Sicily were the dominant source for more than a century. By the late 18th century, about 2,000 tonnes per year of sulfur were imported into Marseille, France, for the production of sulfuric acid for use in the Leblanc process. In industrializing Britain, with the repeal of tariffs on salt in 1824, demand for sulfur from Sicily surged. The increasing British control and exploitation of the mining, refining, and transportation of sulfur, coupled with the failure of this lucrative export to transform Sicily's backward and impoverished economy, led to the Sulfur Crisis of 1840, when King Ferdinand II gave a monopoly of the sulfur industry to a French firm, violating an earlier 1816 trade agreement with Britain. A peaceful solution was eventually negotiated by France. In 1867, elemental sulfur was discovered in underground deposits in Louisiana and Texas. The highly successful Frasch process was developed to extract this resource, and the United States replaced Sicily as the main producer of sulfur worldwide in the early 20th century. Since the advent of the contact process, the majority of sulfur is used to make sulfuric acid for a wide range of uses, particularly fertilizer. In recent times, the main source of sulfur has become petroleum and natural gas. This is due to the requirement to remove sulfur from fuels in order to prevent acid rain, and has resulted in a surplus of sulfur.
==== Small RNA ==== At first, regulatory RNA was thought to be a eukaryotic phenomenon, a part of the explanation for why so much more transcription in higher organisms was seen than had been predicted. But as soon as researchers began to look for possible RNA regulators in bacteria, they turned up there as well, termed as small RNA (sRNA). Currently, the ubiquitous nature of systems of RNA regulation of genes has been discussed as support for the RNA World theory. There are indications that the enterobacterial sRNAs are involved in various cellular processes and seem to have significant role in stress responses such as membrane stress, starvation stress, phosphosugar stress and DNA damage. Also, it has been suggested that sRNAs have been evolved to have important role in stress responses because of their kinetic properties that allow for rapid response and stabilisation of the physiological state. Bacterial small RNAs generally act via antisense pairing with mRNA to down-regulate its translation, either by affecting stability or affecting cis-binding ability. Riboswitches have also been discovered. They are cis-acting regulatory RNA sequences acting allosterically. They change shape when they bind metabolites so that they gain or lose the ability to bind chromatin to regulate expression of genes.
Materiel or matériel (; from French matériel 'equipment, hardware') is supplies, equipment, and weapons in military supply-chain management, and typically supplies and equipment in a commercial supply chain context.
Sources: en.wikipedia.org
It is a synthetic cyclic peptide designed as an analog of alpha-melanocyte-stimulating hormone. It acts on melanocortin receptors and is best known from research into pigmentation. It is not an approved pharmaceutical product.
No regulatory agency has approved it for any indication. It is encountered as a research chemical sold outside pharmaceutical supply chains. Products marketed this way are not subject to the manufacturing and labeling requirements that apply to approved drugs.
Reports describe increased skin pigmentation as well as side effects such as nausea, flushing, and changes to existing moles. Much of the evidence comes from small studies and case reports rather than large trials. The long-term safety profile is therefore uncertain.
No. It is a laboratory-made peptide, while the natural hormone is alpha-melanocyte-stimulating hormone, a longer peptide produced by the pituitary gland and by skin cells. Melanotan-2 mimics only a short active region of that hormone and contains non-natural residues such as D-phenylalanine.