If you have been reading about Melanotan II and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2025-09-25. 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-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.
| 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.
As the head group forms such compact bicycle structure, the head group area is quite small relative to the big tail region consisting of 4 acyl chains. Based on this special structure, the fluorescent mitochondrial indicator, nonyl acridine orange (NAO) was introduced in 1982, and was later found to target mitochondria by binding to CL. NAO has a very large head and small tail structure which can compensate with cardiolipin's small head and large tail structure, and arrange in a highly ordered way. Several studies were published utilizing NAO both as a quantitative mitochondrial indicator and an indicator of CL content in mitochondria. However, NAO is influenced by membrane potential and/or the spatial arrangement of CL, so it's not proper to use NAO for CL or mitochondria quantitative studies of intact respiring mitochondria. But NAO still represents a simple method of assessing CL content.
Doug Ford is the 26th and current premier of Ontario (French: Premier ministre de l'Ontario), Canada. He won a majority in the 2018 Ontario general election, as leader of the Ontario Conservative Party caucus in the Legislative Assembly of Ontario and was sworn in as premier on June 29, 2018. He was re-elected with an increased majority in 2022, and again after calling a snap election for February 27, 2025.
== Natural occurrence == Hydrogen peroxide is produced by various biological processes mediated by enzymes. Hydrogen peroxide has been detected in surface water, in groundwater, and in the atmosphere. It can also form when water is exposed to UV light. Sea water contains 0.5 to 14 μg/L of hydrogen peroxide, and freshwater contains 1 to 30 μg/L. Concentrations in air are about 0.4 to 4 μg/m3, varying over several orders of magnitude depending in conditions such as season, altitude, daylight and water vapor content. In rural nighttime air it is less than 0.014 μg/m3, and in moderate photochemical smog it is 14 to 42 μg/m3. The amount of hydrogen peroxide in biological systems can be assayed using a fluorometric assay.
Sources: en.wikipedia.org
Back pain can also be referred from another source. Referred pain occurs when pain is felt at a location different than the source of the pain. Disease processes that can present with back pain include pancreatitis, kidney stones, severe urinary tract infections and abdominal aortic aneurysms.
Lajos Kisfaludy (30 August 1924 in Gemer, Czechoslovakia − 30 October 1988 in Budapest, Hungary) was a Hungarian chemical engineer, a corresponding member of the Hungarian Academy of Sciences. He is renowned for his research in the field of peptide synthesis and medicinal chemistry. From 1943, he studied at the Budapest University of Technology and graduated in 1948 as a chemical engineer. Until 1956, he taught at the Department of Organic Chemistry of the university. In 1956, he started to work for the Kőbánya Pharmaceutical Factory in Budapest as director and research professor of the synthesis laboratory, a position that he held from 1958 until his death. His main research was in the field of medicinal chemistry. He introduced new methods and protecting groups into the process of peptide synthesis. He contributed to the chemical synthesis of human hormones such as oxytocin and adrenocorticotropic hormone. As a result of his experiments, nearly 80 medicines were synthesized and introduced to the market (including Cavinton, Seduxen and Suprastin). He was a corresponding (1982) member of the Hungarian Academy of Sciences.
=== Pharmacodynamics === Mitragynine acts on a variety of receptors in the central nervous system (CNS), most notably the μ-, δ-, and κ-opioid receptors. The nature of mitragynine's interaction with opioid receptors has yet to be fully classified, with some reports suggesting partial agonist activity at the μ-opioid receptor and others suggesting full agonist activity. Additionally, mitragynine is known to interact with δ- and κ-opioid receptors as well, but these interactions remain ambiguous, with some reports indicating mitragynine as a delta and κ-opioid receptor competitive antagonist and others as a full agonist of these receptors. In either case, mitragynine is reported to have lower affinity to delta and κ-opioid receptors compared to μ-opioid receptors. Mitragynine is also known to interact with dopamine D2, adenosine, serotonin, and alpha-2 adrenergic receptors, though the significance of these interactions is not fully understood. Additionally, several reports of mitragynine pharmacology indicate potential biased agonism activity favoring G protein signaling pathways independent of β-arrestin recruitment, which was originally thought to be a primary component in reducing opioid-induced respiratory depression. However, recent evidence suggests that low intrinsic efficacy at the μ-opioid receptor is responsible for the improved side effect profile of mitragynine, as opposed to G protein bias.
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.