Melanotan II comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-12-27. Numbers and descriptions here follow the published literature rather than marketing material.
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its structure substitutes a lactam bridge between side chains to increase stability relative to the native hormone. The compound is also known by the shorthand MT-II and by several non-proprietary synonyms used in research catalogues. It is not an approved therapeutic product in any major jurisdiction; material sold under this name is typically offered as a laboratory reagent rather than as a medicine.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
The material is commonly handled as a lyophilized powder in sealed vials. The solid dissolves readily in water and in polar organic solvents, producing a clear solution after reconstitution. Light, heat and repeated freeze-thaw cycles are the concerns most often raised in handling guidance, because peptide bonds and the constrained ring can degrade. Working solutions are generally prepared fresh, and material left in solution is treated as less stable than the dry form. These properties shape how laboratories store and aliquot reference material.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry. Retention time supports identity, while the mass spectrum confirms the molecular weight of the intact peptide. Purity is frequently reported as a percentage of total peak area, a figure that depends on the wavelength, column and gradient used. Impurity profiling may also look for truncated sequences, oxidised forms and residual counterions. Amino acid analysis and peptide mapping provide orthogonal confirmation when required.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analogue of alpha-melanocyte-stimulating hormone |
| Common synonyms | MT-II; melanotan 2 | No internationally accepted non-proprietary name |
| Typical presentation | Lyophilised powder in a sealed vial | Often supplied alongside a separate diluent |
| Regulatory status | Unapproved therapeutic substance | Customs seizure reported in several jurisdictions |
| Reported route in use | Subcutaneous injection | Self-administered outside clinical settings |
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.
Quality assessment of research-grade peptide rests mainly on reversed-phase high-performance liquid chromatography for purity and on mass spectrometry for identity confirmation. A single main peak above a stated threshold, commonly ninety-eight percent by peak area, is the usual release criterion applied by suppliers. Independent analyses commissioned by laboratories and consumer organisations have repeatedly reported discrepancies between label claims and measured content, including truncated sequences, residual trifluoroacetate, and lower-than-declared peptide mass. Those findings do not establish that every supplier is unreliable, but they indicate that purity figures printed on a vial are claims requiring verification rather than settled facts.
Regulatory treatment varies by jurisdiction and has changed over time. In several countries the peptide is handled as an unapproved prescription medicine, and import or sale for human use is restricted, while elsewhere it falls under poisons or controlled-substance schedules. Enforcement activity against online vendors has been reported in Australia, New Zealand, the United Kingdom and the United States. Scholarly writing discusses melanotan-2 chiefly as an experimental tool and as a case study in unregulated peptide supply, and its precise legal position in any given country should be checked against current national schedules.
=== Halides === The colorless curium(III) fluoride (CmF3) can be made by adding fluoride ions into curium(III)-containing solutions. The brown tetravalent curium(IV) fluoride (CmF4) on the other hand is only obtained by reacting curium(III) fluoride with molecular fluorine:
==== Heat-sensing pits ==== Aside from their eyes, rattlesnakes are able to detect thermal radiation emitted by warm-blooded organisms in their environment. Functioning optically like a pinhole camera eye, thermal radiation in the form of infrared light passes through the opening of the pit and strikes the pit membrane located in the back wall, warming this part of the organ. Due to the high density of heat-sensitive receptors innervating this membrane, the rattlesnake can detect temperature changes of 0.003 °C or less in its immediate surroundings. Infrared cues from these receptors are transmitted to the brain by the trigeminal nerve, where they are used to create thermal maps of the snake's surroundings. Due to the small sizes of the pit openings, typically these thermal images are low in resolution and contrast. Nevertheless, rattlesnakes superimpose visual images created from information from the eyes with these thermal images from the pit organs to more accurately visualize their surroundings in low levels of light. Research conducted recently on the molecular mechanism of this ability suggests the temperature sensitivity of these pit organs is closely linked to the activity of transient receptor potential ankyrin 1, a temperature-sensitive ion channel saturated in the pit membrane.
While for many nutrients, the US Department of Agriculture uses food composition data combined with food consumption survey results to estimate average consumption, the surveys and reports do not include pantothenic acid in the analyses. Less formal estimates of adult daily intakes report about 4 to 7 mg/day. The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL are defined the same as in the US. For women and men over age 11, the Adequate Intake (AI) is set at 5 mg/day. AI for pregnancy is 5 mg/day, for lactation 7 mg/day. For children ages 1–10 years, the AI is 4 mg/day. These AIs are similar to the US AIs.
Sources: en.wikipedia.org
As can be seen in the formula, the variation of K must be isosteric, that is, at constant coverage. If we start from the BET isotherm and assume that the entropy change is the same for liquefaction and adsorption, we obtain
DNA spore photoproduct lysase (SPL) is a radical SAM that can repair DNA thymine dimers (spore product, SP) caused by UV radiation. Despite the remaining unknowns and controversies involving SPL-catalyzed reaction, it is certain that SPL utilizes SAM as a cofactor to generate 5'-dAdo radical to revert SP to two thymine residues. HydG is a radical SAM responsible for generating CO and CN− ligands in the [Fe-Fe]-hydrogenase (HydA) in various anaerobic bacteria. Radical SAM MoaA and MoaC are involved in converting GTP into cyclic pyranopterin monophosphate (cPMP). Overall, both play roles in molybdopterin biosynthesis.
A street in Tirana, Albania, located directly outside the Albanian Parliament and formerly known as Rruga Punëtorët e Rilindjes, was renamed after Bush a few days before he made the first-ever visit by an American president to Albania in June 2007. In 2012, Estonian president Toomas Hendrik Ilves awarded Bush the Order of the Cross of Terra Mariana for his work in expanding NATO. Two elementary schools are named after him: one in Stockton Unified School District in Stockton, California, and one in Wylie Independent School District in St. Paul, Texas, in the Dallas-Fort Worth area.
Sources: en.wikipedia.org
No. No major regulatory agency has granted a marketing authorisation for melanotan II as a medicine. Products sold under this name are generally presented as laboratory reagents and are not subject to the batch-release testing applied to approved drugs.
It was developed in the 1980s by researchers investigating analogues of alpha-melanocyte-stimulating hormone for pigmentation and related endpoints. Early work included small human studies during the 1990s. Development did not progress to licensing, and the compound remained a research and grey-market item.
Peptides are prone to truncation, oxidation and aggregation during synthesis and handling. Without independent testing, a buyer cannot confirm the identity or the content of a vial. Analytical surveys of unapproved peptide products have repeatedly found discrepancies between label claims and measured composition.
The dry powder is more stable during transport and storage than a solution. It also allows a known amount of material to be reconstituted at a chosen concentration.