melanocortin receptor raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-02-20. Anything still debated is marked as such rather than presented as settled.
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.
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.
Published research on the compound remains limited. Much of the human data comes from small, early-stage studies rather than large controlled trials, and several questions about effects and variability between individuals remain open. Investigators have examined receptor activity, pigment pathways, and related physiological responses in laboratory and animal models. Findings from those models do not automatically translate to human outcomes. Reviews frequently note the scarcity of rigorous clinical evidence and call for better-characterized study material.
Because the substance circulates mainly through informal markets, verification is a recurring theme in technical discussion. Independent analyses have found that labeled content and actual content can diverge, and that purity varies between samples. Analytical laboratories use reversed-phase chromatography to separate components and mass spectrometry to confirm identity. Isotope-labeled internal standards improve quantification in complex matrices. Such methods describe what a sample contains but say nothing about its sterility, lawful status, or suitability for any use. Open questions remain about how consistently testing is applied across the supply chain.
Regulatory treatment of this peptide varies by country. It holds no marketing authorization as a medicine in the United States, the European Union, or most other jurisdictions. Some countries classify products containing it as prescription-only or unlicensed medicines, which restricts lawful supply. Authorities have issued public notices warning that unregulated products may contain undeclared or incorrect ingredients. The molecule also appears on prohibited lists for competitive sport. These measures address supply oversight rather than any approved therapeutic role.
| Property | Value | Notes |
|---|---|---|
| Compound class | Synthetic cyclic heptapeptide | Alpha-MSH analogue containing a D-phenylalanine residue |
| Molecular formula | C50H69N15O9 | Average molecular mass approximately 1024.2 g/mol |
| Appearance | White to off-white lyophilised powder | Normally supplied as a freeze-dried solid in a sealed vial |
| Solubility | Freely soluble in water and polar solvents | Dissolves readily in aqueous buffers and in alcohol-water mixtures |
| Receptor targets | MC1R, MC3R, MC4R, MC5R | Acts as a non-selective melanocortin receptor agonist |
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
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.
Analytical confirmation of identity relies on mass spectrometry, most often coupled to liquid chromatography. Reversed-phase high-performance liquid chromatography separates the peptide from related impurities and provides a purity estimate based on peak area. Electrospray ionization mass spectrometry then confirms the expected molecular mass, while tandem mass spectrometry can map the fragment sequence. For research-grade material, these two techniques together form the standard minimum. Purity figures reported by vendors are frequently not traceable to an independent laboratory.
Independent verification is central to quality control because the compound is not produced under pharmaceutical manufacturing standards. Third-party laboratories can measure purity, identity, residual solvents, and microbial contamination, though the scope of testing varies between services. Reported analyses of vendor samples have shown batch-to-batch variation in peptide content and the presence of truncated or oxidized species. How much of this variation reflects synthesis conditions versus storage and shipping is not well characterized. No harmonized reference standard exists for the material as sold.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, the naturally occurring peptide involved in pigmentation signalling. Its sequence is conventionally written as Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, with a lactam bridge joining the aspartate side chain to the lysine side chain. The empirical formula is C50H69N15O9 and the monoisotopic mass lies near 1023.5 daltons. N-terminal acetylation and the D-configured phenylalanine both increase resistance to enzymatic breakdown compared with the parent hormone.
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.
=== April === 2 April – Stand-up comedian Janey Godley wins the inaugural Billy Connolly Spirit of Glasgow Award at the Glasgow International Comedy Festival. 4 April – Data produced by Public Health Scotland indicated that one in three people referred with urgent suspicion of cancer are waiting longer than the target date of 62 days. 5 April – Police arrest former SNP chief executive Peter Murrell as part of their investigation into the party's finances, but release him without charge pending further investigation. 6 April – Following a trial at the High Court in Edinburgh, Kashif Anwar is convicted of the murder of his pregnant wife, Fawziyah Javed, who he pushed from a rocky outcrop on Arthur's Seat, during a holiday in Edinburgh in September 2021. He is sentenced to life imprisonment with a minimum term of 20 years. 7 April BBC News reports that Johnston Carmichael, the accountants who audit the SNP's accounts, have resigned from the role, citing a their decision to do so as having been taken following a review of their clients. The Unite union announces that around 1,300 offshore workers are to stage a 48-hour strike from 24 April over pa, affecting production at dozens of oil and gas platforms. Around 100 workers at Rosyth Dockyard belonging to Unite have voted to strike between 17 April and 10 July in a disagreement with their employers over pay. 8 April – SNP president Mike Russell tells The Herald newspaper he does not think Scottish independence can be achieved "right now", and that the party is facing its biggest crisis for 50 years.
Provides straightforward information about effects arising from individual compounds in complex or natural samples separated in parallel. Combines chromatographic separation with effect-directed detection using enzymatic or biological assays. Helps to select important compounds from a sample for further characterization using high-resolution mass spectrometry. Offers unique benefits such as super-hyphenation, minimum sample preparation requirements, detection of multi-modulating compounds, and distinguishing agonistic versus antagonistic effects.
=== Vishal Y Joshi's method === Joshi et al. (2006) propose the Koenigs-Knorr reaction in the stereoselective synthesis of alkyl D-glucopyranosides via glycosylation, with the exception of using lithium carbonate which is less expensive and toxic than the conventional method of using silver or mercury salts. D-glucose is first protected by forming the peracetate by addition of acetic anhydride in acetic acid, and then addition of hydrogen bromide which brominates at the 5-position. On addition of the alcohol ROH and lithium carbonate, the OR replaces the bromine and on deprotecting the acetylated hydroxyls the product is synthesized in relatively high purity. It was suggested by Joshi et al. (2001) that lithium acts as the nucleophile that attacks the carbon at the 5-position and through a transition state the alcohol is substituted for the bromine group. Advantages of this method as well as its stereoselectivity and low cost of the lithium salt include that it can be done at room temperature and its yield compares relatively well with the conventional Koenigs-Knorr method.
=== Electron ionization === By far the most common and perhaps standard form of ionization is electron ionization (EI). The molecules enter into the MS (the source is a quadrupole or the ion trap itself in an ion trap MS) where they are bombarded with free electrons emitted from a filament, not unlike the filament one would find in a standard light bulb. The electrons bombard the molecules, causing the molecule to fragment in a characteristic and reproducible way. This "hard ionization" technique results in the creation of more fragments of low mass-to-charge ratio (m/z) and few, if any, molecules approaching the molecular mass unit. Hard ionization is considered by mass spectrometrists as the employ of molecular electron bombardment, whereas "soft ionization" is charge by molecular collision with an introduced gas. The molecular fragmentation pattern is dependent upon the electron energy applied to the system, typically 70 eV (electronvolts). The use of 70 eV facilitates comparison of generated spectra with library spectra using manufacturer-supplied software or software developed by the National Institute of Standards (NIST-USA). Spectral library searches employ matching algorithms such as Probability Based Matching and dot-product matching that are used with methods of analysis written by many method standardization agencies. Sources of libraries include NIST, Wiley, the AAFS, and instrument manufacturers.
Sources: en.wikipedia.org
==== Closed-loop systems ==== Unlike the continuous sensor alone, the closed-loop system requires no user input in response to reading from the monitor; the monitor and insulin pump system automatically delivers the correct amount of hormone calculated from the readings transmitted. The system is what makes up the artificial pancreas device.
Ethel and Howard Florey published the results of clinical trials of penicillin in The Lancet on 27 March 1943, reporting the treatment of 187 cases of sepsis with penicillin. It was upon this medical evidence that the British War Cabinet set up the Penicillin Committee on 5 April 1943. The committee consisted of Cecil Weir, Director General of Equipment, as chairman; Alexander Fleming; Howard Florey; V. D. Allison, another one of Fleming's former research students; Sir Percival Hartley, the head of the MRC; and representatives from pharmaceutical companies. This led to the mass production of penicillin by the next year.
US Fleet Tracking is a privately owned company that specializes in manufacturing and distributing GPS Tracking products and accessories designed to enable businesses and individuals to monitor their mobile assets and vehicle fleets, tracking those vehicles live, in realtime, as they move.
=== Vitamin D synthesis === PTH upregulates the activity of 1-α-hydroxylase enzyme, which converts 25-hydroxycholecalciferol, the major circulating form of inactive vitamin D, into 1,25-dihydroxycholecalciferol, the active form of vitamin D, in the kidney.
Biological therapy, the use of medications called biopharmaceuticals or biologics that are tailored to specifically target an immune or genetic mediator of disease, plays a major role in the treatment of inflammatory bowel disease. Even for diseases of unknown cause, molecules that are involved in the disease process have been identified, and can be targeted for biological therapy. Many of these molecules, which are mainly cytokines, are directly involved in the immune system. Biological therapy has found a niche in the management of cancer, autoimmune diseases, and diseases of unknown cause that result in symptoms due to immune related mechanisms. Inflammatory bowel disease (IBD), a collection of systemic diseases involving inflammation of the gastrointestinal tract, includes two (or three) diseases of unknown causation: ulcerative colitis, which affects only the large bowel; Crohn's disease, which can affect the entire gastrointestinal tract; and indeterminate colitis, which consists of large bowel inflammation that shows elements of both Crohn's disease and ulcerative colitis. Although the causes of these diseases are unknown, genetic, environmental, immune, and other mechanisms have been proposed. Of these, the immune system plays a large role in the development of symptoms. Given this, a variety of biological therapies (such as TNF inhibitors and interleukin antagonists) have been developed for the treatment of these diseases.
Sources: en.wikipedia.org
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.
No approved regulatory indication exists in major markets. An approval exists for a different peptide, afamelanotide, which is used for a rare photosensitivity disorder called erythropoietic protoporphyria. Melanotan-2 itself remains a research compound with no cleared clinical role.
Melanocortin-1 receptors on melanocytes are the receptor most closely linked to pigment production. The peptide is not selective, however, and also activates melanocortin-3, melanocortin-4, and melanocortin-5 receptors. That lack of selectivity is the usual explanation offered for both its range of observed effects and its off-target effects.
Only a small number of early-stage human studies have been reported, and most were limited in size and duration. No large late-stage program has established a general efficacy or safety profile. The evidence base is therefore thin compared with approved medicines.