amino acid substitution raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-04-28 and is reviewed periodically as new material appears.
The compound was developed in the late 1980s and early 1990s by academic researchers investigating melanocortin signaling and pigmentation. Early work explored whether synthetic analogs could reproduce effects of the natural hormone under controlled conditions. The molecule never advanced through the full regulatory pathway required for approval as a medicine. From the mid-2000s onward it appeared in unregulated consumer markets, often distributed through informal channels. That gap between research origins and commercial availability shapes how the compound is discussed today.
Melanotan-2 is a synthetic peptide designed as an analog of alpha-melanocyte-stimulating hormone, a signaling molecule produced in the pituitary and skin. Its structure is a linear chain of seven amino acids that folds into a ring through an internal lactam bridge joining two side chains. The compound is sometimes written as MT-II or MEL-2 in informal and commercial contexts. It belongs to the melanocortin peptide family, a group of short signaling molecules that share a conserved core sequence recognized by melanocortin receptors.
Two structural changes distinguish the synthetic peptide from the natural hormone. A norleucine residue replaces methionine at one position, and a D-configured phenylalanine replaces the natural L-form at another. Both substitutions slow enzymatic breakdown, which extends the molecule's persistence relative to the parent hormone. The lactam bridge further constrains the backbone into a stable conformation. These features are standard design strategies in peptide chemistry and are not unique to this compound; they appear across many research peptides built for improved stability.
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
No regulatory authority has approved melanotan-2 for human use, and several countries classify it as a prescription-only or controlled substance, which restricts lawful supply. Material sold online is generally labelled as a research chemical and is not required to meet pharmaceutical standards of identity or purity. Published human data consist mainly of small uncontrolled studies, case reports and adverse-event notifications, so the evidence base is descriptive rather than confirmatory. Whether repeated melanocyte stimulation alters long-term naevus behaviour remains an open question that no completed trial has resolved.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic cyclic heptapeptide | Analog of alpha-MSH with an internal lactam bridge |
| Molecular weight | Approximately 1024 daltons | Free base value; salt forms differ |
| Appearance | White to off-white powder | Usually supplied as a lyophilized solid |
| Solubility | Freely soluble in water | Poorly soluble in nonpolar solvents |
| Typical storage | −20 °C, dry, protected from light | Repeated freeze-thaw cycles degrade peptides |
Published human data come mostly from small, short studies rather than large controlled trials. Reported outcomes include increased skin pigmentation and, in some reports, effects on appetite and libido, but sample sizes are small and follow-up is limited. Whether long-term use produces durable pigment changes or adverse effects is not established. Because products sold outside pharmacies are not standardized, the actual content of any given vial is often unknown. Independent testing of such material is uncommon.
Melanotan II is a synthetic cyclic heptapeptide analog derived from the core sequence of alpha-melanocyte-stimulating hormone. Researchers at the University of Arizona synthesized it during the 1980s while studying pigmentation and appetite signaling. The compound is not an approved medicine in any major jurisdiction and appears mainly in laboratory and research-chemical settings. Its structure incorporates a lactam bridge between side chains, which constrains the ring and slows enzymatic breakdown relative to the natural hormone.
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.
=== Purine metabolism === GMP synthase is the second step in the generation of GMP from IMP; the first step occurs when IMP dehydrogenase generates XMP, and then GMP synthetase is able to react with glutamine and ATP to generate GMP. IMP may also be generated into AMP by adenylosuccinate synthetase and then adenylosuccinate lyase.
=== Simplified clinical approach === Kalra has developed several clinically applicable concepts that simplify obesity management, including bariatric triage, gut guardianship, medical gastronomy, and obesity-friendly language. He has addressed the pathogenesis, comorbidities, and complications of obesity in multiple review papers, including a recent review on MASLD in Endocrine Clinics of North America. Several papers led by Kalra serve as practical guides for clinicians new to obesity management, outlining stepwise protocols for setting up obesity clinics and evaluating and managing obesity.
Jensen "for their discoveries concerning nuclear shell structure" and Eugene Paul Wigner "for his contributions to the theory of the atomic nucleus and the elementary particles, particularly through the discovery and application of fundamental symmetry principles". 1964: American mathematician Irene Stegun completed the work which led to the publication of Handbook of Mathematical Functions, a widely used and widely cited reference work in applied mathematics. 1964: British chemist Dorothy Crowfoot Hodgkin received the Nobel Prize in Chemistry "for her determinations by X-ray techniques of the structures of important biochemical substances". 1964: Egyptian physician and medical geneticist Nemat Hashem established the first medical genetics clinic in the Arab world at Ain Shams University in Cairo. 1964: Scottish virologist June Almeida made the first identification of a human coronavirus. 1965: Sister Mary Kenneth Keller became the first American woman to receive a Ph.D. in computer science. Her thesis was titled "Inductive Inference on Computer Generated Patterns". 1966: Japanese immunologist Teruko Ishizaka, working with Kimishige Ishizaka, discovered the antibody class Immunoglobulin E (IgE). 1966: Serbian astrophysicist Mirjana Vukićević-Karabin founded the School of Astrophysics at the University of Belgrade 1966: Irish chemist Eva Philbin became the first woman president of the Institute of Chemistry of Ireland. 1967: British astrophysicist Jocelyn Bell Burnell co-discovered the first radio pulsars.
27 December – The Met Office issues a yellow weather warning for rain over Hogmanay, starting on 30 December and lasting over the New Year. Public Health Scotland says health services in Scotland are under "acute pressure" following a surge in flu cases. Caledonian MacBrayne is forced to reduce the number of passengers allowed on the MV Isle of Mull to 45 per journey after failing a safety check. 29 December – Emergency services searching for keen wild swimmer Ian Napier, missing from the Scousburgh Bay area since 27 December, find a body in the sea near Shetland. 30 December – Edinburgh's Hogmanay celebrations are cancelled amid weather warnings for heavy rain, high winds and snow over the New Year. 2025 New Year Honours: Among those to be recognised in the New Year Honours are broadcaster Jackie Bird (MBE), footballer and broadcaster Alan Hansen (MBE) and Olympic swimmer Duncan Scott (OBE).
Sources: en.wikipedia.org
=== Legal status === On 24 March 2022, the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Camcevi, intended for the treatment of the cancer of the prostate in adult men when the cancer is "hormone-dependent", which means that it responds to treatments that reduce the levels of the hormone testosterone. The applicant for this medicinal product is Accord Healthcare S.L.U. Leuprorelin was approved for medical use in the European Union in May 2022.
Low Apgar scores, <5 at 5 minutes and 10 minutes. Floppiness, or unreactive to sights or sounds, or more tense and agitated. Low heart rate. Low blood pressure. Poor muscle tone and absent reflexes. Weak breathing, no breathing at all, or rapid breathing. Need for resuscitation after delivery. Weak cry. Bluish or pale skin color. Excessive acid in the blood. Seizures or abnormal movements. Problems feeding
In rail transport, the Single European Railway Directive 2012 requires that ownership of tracks and operating companies are separated to prevent conflicts of interest and pricing, particularly to ensure that trains can run from one member state to another. Most European railways are publicly owned, and each train enterprise must have separate accounts and member states should run railways 'at the lowest possible cost for the quality of service required'. The Rail Passenger Rights Regulation 2007 article 17 states that 25% of a ticket price should be refunded if there is a one-hour delay, and 50% over two hours, with a threshold of €4 to claim. Passengers have a right to take bicycles on trains where they are not overcrowded, there must be clear information on tickets, and there are rights to make reservations. Finally, in air transport, under the Flight Compensation Regulation (EC) No 261/2004 there is a minimum right of €250 compensation for 2 hour delay on 1500 km flight, €400 compensation for 3 hour delay or more on a 1500–3500 km flight, and €600 for 4 hours in flights over 3500 km flight, plus the right to refreshments, hotels, and alternative transport. There are not yet duties on airline companies to invest in research for clean fuels, and eliminate unnecessary flight paths when clean land transport alternatives (such as high-speed rail) exist. Finally, the 'right to housing assistance' is a basic part of EU law. House prices are affected by monetary policy (above), but otherwise the EU's involvement is so far limited to minimal environmental standards.
However, given the potential for hypersensitivity reactions in DM, their use is generally limited to patients who have previously responded well and tolerated these therapies, rather than being routinely employed in DM.
== Treatment == Treatment for myositis depends on the underlying cause. For myositis, which is caused by a viral infection, no treatment is typically needed. For myositis caused by a bacterial infection, antibiotics can be used. For myositis caused by a medication, it is important to stop using that medication. There are a variety of treatment options available if myositis is caused by an autoimmune disease. Glucocorticoids are often the first choice for treatment. This drug works to weaken the immune system so that it is not able to attack the muscles. It is a type of steroid and can cause a wide array of side effects, such as mood changes, increased hunger, trouble sleeping, etc. Another treatment option is a steroid-sparing immunosuppressive agent. This also works to weaken the immune system but does not cause the side effects that steroids do. Another treatment option is a class of drugs called biologics. Also, intravenous immunoglobulins (IVIg) have been shown to be effective in the treatment of myositis caused by an autoimmune disease.
Sources: en.wikipedia.org
Carbon concentration in cement spans from ≈5% in cement structures to ≈8% in the case of roads in cement. Cement manufacturing releases CO2 in the atmosphere both directly when calcium carbonate is heated, producing lime and carbon dioxide, and also indirectly through the use of energy if its production involves the emission of CO2. The cement industry produces about 10% of global human-made CO2 emissions, of which 60% is from the chemical process, and 40% from burning fuel. A Chatham House study from 2018 estimates that the 4 billion tonnes of cement produced annually account for 8% of worldwide CO2 emissions. Nearly 900 kg of CO2 are emitted for every 1000 kg of Portland cement produced. In the European Union, the specific energy consumption for the production of cement clinker has been reduced by approximately 30% since the 1970s. This reduction in primary energy requirements is equivalent to approximately 11 million tonnes of coal per year with corresponding benefits in reduction of CO2 emissions. This accounts for approximately 5% of anthropogenic CO2. The majority of carbon dioxide emissions in the manufacture of Portland cement (approximately 60%) are produced from the chemical decomposition of limestone to lime, an ingredient in Portland cement clinker. These emissions may be reduced by lowering the clinker content of cement. They can also be reduced by alternative fabrication methods such as the intergrinding cement with sand or with slag or other pozzolan type minerals to a very fine powder.
== Medical uses == Carticel is a procedure for restoring articular knee cartilage with autologous chondrocyte implantation; it was the first cell therapy to be approved by the U.S. Food and Drug Administration, under accelerated approval in 1997. In Australia, Ortho-ACI, a suspension of cultured autologous chondrocytes, is indicated for use in the treatment of cartilage lesions associated with the knee, patella, and ankle.
== Mechanism of action == Icotrokinra is a targeted oral peptide that selectively binds to and blocks the interleukin 23 receptor (IL-23R), thereby inhibiting IL-23-mediated signaling. The drug demonstrates high affinity for the human IL-23 receptor with a dissociation constant (KD) of 7.1 pM and inhibits IL-23-induced STAT3 phosphorylation in peripheral blood mononuclear cells with an IC50 of 5.6 pM. The IL-23 pathway plays a central role in the inflammatory cascade underlying various autoimmune conditions, particularly those involving Th17 cells. Unlike injectable biologics that target IL-23 or its receptor, icotrokinra offers the convenience of oral administration while maintaining selective receptor binding.
Turin is home to one of Italy's oldest universities, the University of Turin, including its affiliated Collegio Carlo Alberto, which ranks among the best universities in the country. Another established university in the city is the Polytechnic University of Turin, ranking among Top 50 universities in the world and #1 in Italy in the fields of engineering, technology and computer science ("Academic Ranking of World Universities" published by Shanghai Jiao Tong University). Turin also hosts the United Nations System Staff College, the European Training Foundation, and a campus of the ESCP business school, ranked among the 10 best business schools in Europe. Moreover, the city hosts three small English language post-secondary institutions: St. John International University, International University College of Turin, and the Turin School of Development. In 2025, Turin becomes the first city in Italy with a plan to combat Islamophobia.
=== 18 March === President Putin visited Crimea on the ninth anniversary of the peninsula's annexation. The Black Sea Grain Initiative between Ukraine and Russia, which was due to expire on 18 March, was extended.
Sources: en.wikipedia.org
It is a synthetic seven-amino-acid peptide modeled on alpha-melanocyte-stimulating hormone. It carries two non-natural substitutions and a cyclic bridge that increase its stability relative to the natural hormone. It circulates as a research chemical and is not an approved medicine.
Melanotan-1, also called afamelanotide, is a shorter linear analog with a different amino acid sequence and no lactam ring. It has been evaluated in formal clinical programs, while melanotan-2 has not. The two are distinct molecules and are not interchangeable.
No. Bremelanotide is a related but distinct cyclic peptide that reached approved status for one specific clinical indication. Melanotan-2 is a separate molecule with its own sequence and properties. Shared ancestry in the melanocortin family does not make them the same substance.
No regulatory agency has authorised melanotan-2 as a medicine for any indication. It circulates mainly as a research chemical or through unregulated channels. As a result, identity, purity and content are not independently guaranteed.