This is a working overview of alpha-MSH analogue, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-05-19. Anything still debated is marked as such rather than presented as settled.
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.
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controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports.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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Alpha-MSH analogue with a lactam ring |
| Molecular formula | C50H69N15O9 | Commonly cited value for the neutral peptide |
| Molecular weight | 1024.18 g/mol | Calculated for the free molecule |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water, DMSO and ethanol | Dissolution in pure water is often slow |
Human data remain limited and mostly short-term. Reports describe small trials and observational accounts rather than large controlled studies, so questions about dose-response relationships and long-term effects on melanocytes stay open. Whether repeated exposure alters naevus behaviour is not settled in the published record. Researchers also note that self-administered use outside clinical settings makes actual exposure difficult to quantify. Statements about efficacy and safety should therefore be read as preliminary rather than established.
Melanotan II is a synthetic cyclic heptapeptide that acts as an agonist at melanocortin receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide involved in pigment production. The analogue carries a lactam bridge that constrains the ring and slows enzymatic breakdown relative to the native hormone. In research literature it appears under several abbreviations, and naming conventions are not fully standardized. Published descriptions usually place it within the broader melanocortin agonist family.
Receptor binding at MC1R on melanocytes raises intracellular cyclic AMP and increases expression of tyrosinase and related enzymes. The downstream result is greater synthesis of eumelanin, the dark pigment, without ultraviolet exposure acting as the trigger. The compound is not selective, however, and also engages MC3R, MC4R and MC5R, which are expressed in the central nervous system and elsewhere. That lack of selectivity is the explanation usually offered for effects reported outside pigmentation, including appetite suppression and nausea. Selectivity remains a central theme in comparative studies of related peptides.
Melanocortin receptors comprise five subtypes with distinct tissue distributions and functions. Melanotan-2 is described in the literature as a non-selective agonist that engages several of these subtypes, including MC1R, MC3R, MC4R, and MC5R. MC1R is the subtype most directly linked to melanin production in skin cells. Because the compound is not subtype-selective, its observed effects in experimental settings are generally attributed to activity across multiple receptor pathways rather than to a single target.
Melanotan-2 is a synthetic linear peptide built from seven amino acids arranged in a short chain. Its sequence is commonly written as Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH2, which includes a modified N-terminus and an amidated C-terminus. The molecule belongs to the melanocortin family and acts as a receptor agonist. Structural features such as the D-phenylalanine residue and the Nle substitution are associated with increased stability against enzymatic degradation relative to the natural parent peptide.
=== Applied research === Ben-Tal has participated in research addressing biological systems of medical and security significance. His work has included computational analysis of membrane transport proteins and studies related to molecular mechanisms underlying disease and drug discovery. In collaboration with researchers from Turkey and Israel, he co-led a NATO Science for Peace and Security Programme project on the MntABC transporter of Bacillus anthracis. The project investigated the structure and functional dynamics of the transporter and sought potential compounds capable of inhibiting its activity. Ben-Tal, Türkan Haliloğlu, and Oded Lewinson were the project's co-directors. The project received the 2018 NATO SPS Partnership Prize in the field of chemical, biological, radiological and nuclear defence, with the award presented at NATO headquarters in November 2018.
=== 22 SAS Regiment === Since serving in Malaya, men from the regular army 22 SAS Regiment have taken part in reconnaissance patrols and large scale raiding missions in the Jebel Akhdar War in Oman and conducted covert reconnaissance and surveillance patrols and some larger scale raiding missions in Borneo during the Indonesia–Malaysia confrontation. They returned to Oman in operations against Communist-backed rebels in the Dhofar Rebellion including the Battle of Mirbat. They have also taken part in operations in the Aden Emergency, Northern Ireland, and Gambia. Their Special projects team assisted the West German counterterrorism group GSG 9 at Mogadishu, with Lufthansa Flight 181. The SAS counter terrorist wing famously took part in a hostage rescue operation during the Iranian Embassy Siege in London. SAS were involved throughout Britain's covert involvement in the Soviet–Afghan War; they acted through private military contractor Keenie Meenie Services (or KMS Ltd), training the Afghan Mujaheddin in weapons, tactics and using explosives. They trained the Mujaheddin in Afghanistan and sent them to be trained in Pakistan, Oman and parts of the UK. During the Falklands War B squadron were prepared for Operation Mikado before it was subsequently cancelled while D and G squadrons were deployed and participated in the raid on Pebble Island. Operation Flavius was a controversial operation in Gibraltar against the Provisional Irish Republican Army (PIRA). 22 SAS directed NATO aircraft onto Serb positions and hunted war criminals in Bosnia.
== Animal models == Knockout mice of GPX4 die at embryonic day 8 and conditional inducible deletion in adult mice (neurons) results in degeneration and death in less than a month. Targeted disruption of the mitochondrial GPX4 isoform (mGPX4) caused infertility in male mice and disruption of the nuclear GPX4 isoform (nGPX4) reduced the structural stability of sperm chromatin, yet both knockout mouse models (for mGPX4 and nGPX4) were fully viable. Surprisingly, knockout of GPX4 heterozygously in mice (GPX4+/−) increases their median life span. Knockout studies with GPX1, GPX2, or GPX3 deficient mice showed that cytosolic GPX4 is so far the only glutathione peroxidase that is indispensable for embryonic development and cell survival. As mechanisms to dispose of both hydrogen peroxide and lipid hydroperoxides are essential to life, this indicates that in contrast to the multiple metabolic pathways that can be utilized to dispose of hydrogen peroxide, pathways for the disposal of lipid hydroperoxides are limited. While mammals have only one copy of the GPX4 gene, fish have two copies, GPX4a and GPX4b. The GPX4's appear to play a greater role in the fish GPX system than in mammals. For example, in fish GPX4 activity contributes to a greater extent to total GPX activity, GPX4a is the most highly expressed selenoprotein mRNA (in contrast to mammals where it is GPX1 mRNA) and GPX4a appears to be highly inducible to changes within the cellular environment, such as changes in methylmercury and selenium status.
A tetrahedral intermediate is a reaction intermediate in which the bond arrangement around an initially double-bonded carbon atom has been transformed from trigonal to tetrahedral. Tetrahedral intermediates result from nucleophilic addition to a carbonyl group. The stability of tetrahedral intermediate depends on the ability of the groups attached to the new tetrahedral carbon atom to leave with the negative charge. Tetrahedral intermediates are very significant in organic syntheses and biological systems as a key intermediate in esterification, transesterification, ester hydrolysis, formation and hydrolysis of amides and peptides, hydride reductions, and other chemical reactions.
Sources: en.wikipedia.org
=== Photocatalytic coatings === Photoactive pigments such as TiO2 and ZnO have been used on glass, ceramic, and steel substrates for self-cleaning and antimicrobial purposes. For photocatalytic bactericidal activity in water treatment applications, granular substrate materials have been used in the form of sands supporting mixed anatase/rutile TiO2 coatings. Oxide semiconductor photocatalysts such as TiO2 react with incident irradiation exceeding the material's electronic band-gap resulting in the formation of electron-hole pairs (excitons) and the secondary generation of radical species through reaction with adsorbates at the photocatalyst surface yielding an oxidative or reductive effect that degrades living organisms. Titania has successfully be used as an antimicrobial coating on bathroom tiles, paving slabs, deodorizers, self-cleaning windows, and many more.
5 July Results of the 2024 United Kingdom general election: Sir Keir Starmer becomes the prime minister of the United Kingdom, following a landslide victory for Labour in the general election. The Conservatives are reduced to just 121 seats, the lowest number of MPs in their 190-year history. Among the high-profile losses are former Prime Minister Liz Truss, former cabinet minister Sir Jacob Rees-Mogg, Commons leader Penny Mordaunt, and Defence Secretary Grant Shapps. The Liberal Democrats, led by Sir Ed Davey, achieve their best ever result with 71 seats. The Green Party achieve their best ever result, quadrupling their number of seats to four. Reform UK gain their first seats in Parliament, which includes party leader Nigel Farage taking the constituency of Clacton. The SNP suffers heavy losses, going from 48 seats to just nine. Starmer ministry: Starmer appoints his first cabinet. Angela Rayner becomes Deputy Prime Minister Rachel Reeves becomes Chancellor of the Exchequer David Lammy becomes Foreign Secretary Yvette Cooper becomes Home Secretary John Healey becomes Defence Secretary 6 July Starmer holds his first press conference as prime minister, during which he confirms that the Rwanda deportation scheme is "dead and buried". Euro 2024: After finishing 1–1 at the end of extra time, England beat Switzerland 5–3 on penalties, taking them through to the semi-finals. Andy Murray's Wimbledon career comes to an end after Emma Raducanu withdraws from the mixed doubles.
== Appearance and use == The 917 has two trays for racks, plus a stat rack. Racks that hold five test tubes slide in on the left side of the machine. There are two reagents carousels on the right side of the 917. In the centre, towards the back, are the reaction vessels, where the chemical reactions take place.
==== Member of the Order of the British Empire (MBE) ==== Civil Division Kopu Brown. For public services, lately as Secretary of the Ministry of Internal Affairs. Naomi Iro. For services to the community.
== History == The natriuretic effects of progesterone were demonstrated in 1955, and the development of spironolactone as a synthetic antimineralocorticoid analogue of progesterone shortly followed this. Spironolactone was first synthesized in 1957, was patented between 1958 and 1961, and was first marketed, as an antimineralocorticoid, in 1959. Gynecomastia was first reported with spironolactone in 1962, and the antiandrogenic activity of the medication was first described in 1969. This shortly followed the discovery in 1967 that gynecomastia is an important and major side effect of AR antagonists. Spironolactone was first studied in the treatment of hirsutism in women in 1978. It has since become the most widely used antiandrogen for dermatological indications in women in the United States. Spironolactone was first studied as an antiandrogen in transgender women in 1986, and has since become widely adopted for this purpose as well, particularly in the United States where cyproterone acetate is not available. Early oral spironolactone tablets showed poor absorption. The formulation was eventually changed to a micronized formulation with particle sizes of less than 50 μg, which resulted in approximately 4-fold increased potency.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.
No national medicines agency has approved melanotan-2 for clinical use. Afamelanotide, a related but distinct peptide, holds a marketing authorisation in the European Union for a rare photosensitivity disorder. Melanotan-2 itself is handled as a laboratory chemical.
Its broad activity across melanocortin receptors makes it a tool for probing pigmentation, appetite and vascular signalling. Early trials recorded skin darkening and other effects that were not the original focus of the work. Those observations generated hypotheses that later studies have examined.
No. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.