If you have been reading about melanocortin receptor 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 2025-12-04. Where a claim depends on a specific study, the study is described rather than over-claimed.
Verification of a purchased sample requires documentation linking a batch to a certificate of analysis, and that document should be read for the methods used rather than the headline purity figure. A single chromatographic percentage does not establish identity. Independent laboratories can perform identity and content assays, but no such test establishes that a product is suitable for human use. Claims about efficacy rest largely on small, early studies rather than on replicated controlled trials, and that gap remains open.
Identity testing for a cyclic peptide of this size usually relies on reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The mass spectrum confirms molecular weight, while the chromatographic trace indicates the proportion of related impurities. Tandem mass spectrometry can provide sequence-level information when fragmentation data are compared against a reference standard. Nuclear magnetic resonance is sometimes used to confirm the lactam bridge, although it requires more material and greater operator expertise than routine chromatographic methods.
Lyophilised peptide powder is comparatively stable when kept dry, cold and protected from light. Once dissolved, the molecule is exposed to hydrolysis, oxidation and microbial growth, and degradation accelerates at higher temperatures and in alkaline solution. Repeated freeze-thaw cycles concentrate solutes and promote aggregation. Handling guidance for research peptides commonly clusters around freezer temperatures for powder and short refrigerated use for reconstituted solutions, with pH control and sterile technique applied throughout.
Pharmacologically, melanotan-2 behaves as a non-selective agonist across the melanocortin receptor family. Binding at MC1R on dermal melanocytes promotes eumelanin synthesis, which underlies the tanning response described in early human work. Activity at the centrally expressed MC4R receptor is associated with reported effects on appetite and erectile function. Because the peptide does not discriminate strongly among receptor subtypes, attributing any single observed effect to one receptor pathway is generally not possible without selective antagonists or receptor knockout models.
Research interest has centred on photoprotection and pigmentation, with a smaller body of work on appetite and sexual function. Published human data remain limited to small, frequently uncontrolled studies, and the compound has never received marketing approval from a national medicines regulator. Most laboratory work treats it as a pharmacological tool for probing melanocortin signalling in cell culture or animal models. Whether pigmentation changes observed in people translate into measurable protection against ultraviolet-induced DNA damage remains an open question.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white solid | Lyophilised cake or flake |
| Solubility class | Soluble in water and aqueous buffer | Also soluble in some polar organic solvents |
| Typical storage temperature | Minus 20 degrees Celsius or below | Desiccated and protected from light |
| Typical analytical method | LC-MS/MS | Reversed-phase separation with mass detection |
| Molecular formula | C50H69N15O9 | Free base; salt forms differ |
Melanotan II holds no marketing authorisation from the Food and Drug Administration, the European Medicines Agency, the UK Medicines and Healthcare products Regulatory Agency or Australia's Therapeutic Goods Administration. Products sold under that name are treated as unapproved new drugs, and their sale or import is prohibited in several jurisdictions. Other countries classify the peptide as a prescription-only medicine or place it among controlled substances, so the legal position changes with the destination market. No pharmacopoeial monograph supplies an official specification, because the material is not a licensed pharmaceutical. Consequently, products offered online are not manufactured to a shared public standard.
The peer-reviewed record is dominated by small early-phase studies, case reports and pharmacovigilance summaries rather than large randomised trials. Papers typically examine tanning response, receptor selectivity or patterns of reported adverse events. Many note that participants obtained the peptide outside a clinical setting, which limits verification of composition and administered amount. Reported events vary widely, and causality is frequently unclear because the identity and purity of self-sourced material are unknown. Open questions include whether repeated melanocortin receptor stimulation produces cumulative effects, and how often label claims match actual content.
The peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
Melanotan-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
Thiosulfuric acid forms two types of thiosulfate esters, e.g. O,O-dimethyl thiosulfate ((CH3−O−)2S(=O)(=S)) and O,S-dimethyl thiosulfate ((CH3−O−)(CH3−S−)S(=O)2) Thiocyanic acid forms thiocyanate esters, e.g. methyl thiocyanate (CH3−S−C≡N) (if one classifies thiocyanic acid as an inorganic compound), but forms isothiocyanate "esters" as well, e.g. methyl isothiocyanate (CH3−N=C=S), although organyl isothiocyanates are not classified as esters by the IUPAC Phosphorous acid forms two types of esters: phosphite esters, e.g. triethyl phosphite (P(−O−CH2CH3)3), and phosphonate esters, e.g. diethyl phosphonate (H−P(=O)(−O−CH2CH3)2) Some inorganic acids that are unstable or elusive form stable esters.
=== NSAIDs === Nonsteroidal anti-inflammatory drugs (NSAIDs) and alcohol both increase gastrointestinal events such as gastrointestinal bleeding and peptic ulcers. Taking the two together further increases the risk additively. The risk of stomach bleeding is still increased when aspirin is taken with alcohol or warfarin.
They noted a glycerin-bile-potato mixture grew bacilli that seemed less virulent and changed the course of their research to see if repeated subculturing would produce a strain that was attenuated enough to be considered for use as a vaccine. The BCG strain was isolated after subculturing 239 times during 13 years from a virulent strain on glycerine potato medium. The research continued throughout World War I until 1919 when the now avirulent bacilli were unable to cause tuberculosis disease in research animals. Calmette and Guerin transferred to the Paris Pasteur Institute in 1919. The BCG vaccine was first used in humans in 1921. Public acceptance was slow, and the Lübeck disaster, in particular, did much to harm it. Between 1929 and 1933 in Lübeck, 251 infants were vaccinated in the first 10 days of life; 173 developed tuberculosis and 72 died. It was subsequently discovered that the BCG administered there had been contaminated with a virulent strain that was being stored in the same incubator, which led to legal action against the vaccine's manufacturers. Dr. R. G. Ferguson, working at the Fort Qu'Appelle Sanatorium in Saskatchewan, was among the pioneers in developing the practice of vaccination against tuberculosis. In Canada, more than 600 children from residential schools were used as involuntary participants in BCG vaccine trials between 1933 and 1945. In 1928, the BCG vaccine was adopted by the Health Committee of the League of Nations (predecessor to the World Health Organization (WHO)).
== Comparison with open-weights AI == The Open Source Initiative distinguishes open-source from open weights artificial intelligence when the materials needed to study and modify the model's development process are not also available.
Sources: en.wikipedia.org
A phase 1 dose-ascending trial has been completed as of October 2024. Mebias Discovery has received ongoing grant funding from the National Institute on Drug Abuse (NIDA) for the development of MEB-1170. The chemical structure of MEB-1170 does not yet appear to have been disclosed.
== History == Cold storage companies began to appear when food preservation using ice became commercialized. Ice was farmed from lakes during the winter, and stored, surrounded by straw to insulate it, so that it could be used well into early summer. Ice houses and ice warehouses began to appear as part of the ice trade, and blocks of ice were sold for domestic icebox use and for commercial use in cold storage. In the decades of the 1880s through 1910s, mechanical refrigeration and freezing gradually but increasingly displaced natural ice in this trade. Then in 1922, Clarence Birdseye founded the modern frozen food industry, by pioneering fast freezing (now called blast freezing), based on low temperature freezing of fish practiced by Inuit in Arctic regions.
== Further reading == ABARE (2000). National Plantation Inventory, March, 2000. 4p. Anon. (1997). Timber markets, home and away: Australian growers capitalising on international demand. Pie, Newsletter of Australia's International and National Primary Industries and Energy (PIE) R&D Organisations. Volume 7 (Summer Issue): p14. Avramidis et al. (2023). Basics of wood drying. link: [1] In: Springer Handbook of Wood Science and Technology Bootle, K.R. (1994). Wood in Australia: Types, Properties and Uses. McGraw-Hill Book Company, Sydney. 443p. Desch, H.E. and Dinwoodie, J.M. (1996). Timber: Structure, Properties, Conversion and Use. 7th ed. Macmillan Press Ltd., London. 306p. Doe, P.D., Oliver, A.R. and Booker, J.D. (1994). A Non-Linear Strain and Moisture Content Model of Variable Hardwood Drying Schedules. Proc. 4th IUFRO International Wood Drying Conference, Rotorua, New Zealand. 203-210pp. Haque, M.N. (1997). The Chemical Modification of Wood with Acetic Anhydride. MSc Dissertation. The University of Wales, Bangor, UK. 99p. Hoadley, R. Bruce (2000). Understanding Wood: A Craftsman's Guide to Wood Technology (2nd. ed.). Taunton Press. ISBN 1-56158-358-8. Innes, T. (1996). Improving Seasoned Hardwood Timber Quality with Particular Reference to Collapse. PhD Thesis. University of Tasmania, Australia. 172p. Keey, R.B., Langrish, T.A.G. and Walker, J.C.F. (2000). Kiln-Drying of Lumber. Springer, Berlin. 326p. Kollmann, F.F.P. and Cote, W.A.J. (1968). Principles of Wood Science and Technology. I. Solid Wood. Springer-Verlag, New York. 592p. Kumar, S. (1994).
Sources: en.wikipedia.org
==== Unfinished Tales and The History of Middle-earth ==== In 1980, Christopher Tolkien published a collection of more fragmentary material, under the title Unfinished Tales of Númenor and Middle-earth. In subsequent years (1983–1996), he published a large amount of the remaining unpublished materials, together with notes and extensive commentary, in a series of twelve volumes called The History of Middle-earth. They contain unfinished, abandoned, alternative, and outright contradictory accounts, since they were always a work in progress for Tolkien and he only rarely settled on a definitive version for any of the stories. There is not complete consistency between The Lord of the Rings and The Hobbit, the two most closely related works, because Tolkien never fully integrated all their traditions into each other. He commented in 1965, while editing The Hobbit for a third edition, that he would have preferred to rewrite the book completely because of the style of its prose.
As a result of the mid-17th century Khmelnytsky Uprising, the Zaporozhian Cossacks briefly established an independent state, which later became the autonomous Cossack Hetmanate (1649–1764). It was placed under the suzerainty of the Russian Tsar from 1667 but was ruled by local hetmans for a century. The principal political problem of the hetmans who followed the Pereyeslav Agreement was defending the autonomy of the Hetmanate from Russian/Muscovite centralism. The hetmans Ivan Vyhovsky, Petro Doroshenko and Ivan Mazepa attempted to resolve this by separating Ukraine from Russia. Relations between the Hetmanate and their new sovereign began to deteriorate after the autumn of 1656, when the Muscovites, going against the wishes of their Cossack partners, signed an armistice with the Polish-Lithuanian Commonwealth in Vilnius. The Cossacks considered the Vilnius agreement a breach of the contract they had entered into at Pereiaslav. For the Muscovite tsar, the Pereiaslav Agreement signified the unconditional submission of his new subjects; the Ukrainian hetman considered it a conditional contract from which one party could withdraw if the other was not upholding its end of the bargain. The Ukrainian hetman Ivan Vyhovsky, who succeeded Khmelnytsky in 1657, believed the Tsar was not living up to his responsibility. Accordingly, he concluded a treaty with representatives of the Polish king, who agreed to re-admit Cossack Ukraine by reforming the Polish-Lithuanian Commonwealth to create a third constituent, comparable in status to that of the Grand Duchy of Lithuania.
While most cephalopods can move by jet propulsion, this is a very energy-consuming way to travel compared to the tail propulsion used by fish. The efficiency of a propeller-driven waterjet (i.e. Froude efficiency) is greater than a rocket. The relative efficiency of jet propulsion decreases further as animal size increases; paralarvae are far more efficient than juvenile and adult individuals. Since the Paleozoic era, as competition with fish produced an environment where efficient motion was crucial to survival, jet propulsion has taken a back role, with fins and tentacles used to maintain a steady velocity. Whilst jet propulsion is never the sole mode of locomotion, the stop-start motion provided by the jets continues to be useful for providing bursts of high speed – not least when capturing prey or avoiding predators. Indeed, it makes cephalopods the fastest marine invertebrates, and they can out-accelerate most fish. The jet is supplemented with fin motion; in the squid, the fins flap each time that a jet is released, amplifying the thrust; they are then extended between jets (presumably to avoid sinking). Oxygenated water is taken into the mantle cavity to the gills and through muscular contraction of this cavity, the spent water is expelled through the hyponome, created by a fold in the mantle. The size difference between the posterior and anterior ends of this organ control the speed of the jet the organism can produce. The velocity of the organism can be accurately predicted for a given mass and morphology of animal.
Constantine's dynasty prioritised a lengthy conflict against the comparably powerful Sasanid Persia and ended in 363 with the death of his nephew Julian. The reign of the short Valentinianic dynasty, marked by wars against the Goths, religious debates, and anti-corruption campaigns, ended in the East with the death of Valens at the Battle of Adrianople in 378.
Sources: en.wikipedia.org
Mass spectrometry combined with liquid chromatography provides both molecular weight confirmation and a measure of related impurities. Tandem mass spectrometry adds sequence information. A purity percentage reported without a mass measurement does not confirm what the material is.
No. Lyophilisation slows degradation rather than stopping it, and the rate depends on residual moisture, temperature and light exposure. Freezer storage extends useful life but does not make the material permanent.
A certificate is only as good as its traceability to a specific batch and a named laboratory. Documents lacking batch numbers, method descriptions or laboratory identifiers carry little weight. Confirming what was actually received generally requires a separate test of the material in hand.
It is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, containing seven amino acids with a lactam ring and a D-configured phenylalanine residue. It is supplied as a lyophilised powder for laboratory research.