The short version of melanocortin receptor fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-10-26 and is reviewed periodically as new material appears.
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.
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.
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.
| 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-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.
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.
Melanotan II binds several melanocortin receptor subtypes rather than a single target. MC1R on melanocytes drives melanin synthesis, while MC3R and MC4R participate in energy balance, appetite, and sexual response pathways. This lack of selectivity explains why reported effects extend beyond skin darkening. Substitutions at positions four and seven, including norleucine and D-phenylalanine, increase potency and resistance to peptidases. Understanding which receptor mediates which effect remains an active area of investigation.
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.
Obtaining a sample of the liver after excluding other potential causes of fatty liver can confirm the diagnosis. Treatment for MASLD is weight loss by dietary changes and exercise; bariatric surgery can improve or resolve severe cases. There is some evidence for SGLT-2 inhibitors, GLP-1 agonists, pioglitazone, and vitamin E in the treatment of MASLD. In March 2024, resmetirom was the first drug approved by the FDA for MASH. Approval in the EU followed in August 2025. Those with MASH have a 2.6% increased risk of dying per year. MASLD is the most common liver disorder in the world; about 25–38% of people have it, and the prevalence is rising. It is very common in developed nations, such as the United States, and affected about 75 to 100 million Americans in 2017. Over 90% of obese, 60% of diabetic, and up to 20% of normal-weight people develop MASLD. MASLD was the leading cause of chronic liver disease and the second most common reason for liver transplantation in the United States and Europe in 2017. MASLD affects about 20 to 25% of people in Europe. In the United States, estimates suggest that 30% to 40% of adults have MASLD, and about 3% to 12% of adults have MASH. The annual economic burden was about US$103 billion in the United States in 2016.
Sarcoidosis Granulomatous lung diseases Tuberculosis Fungal infections (e.g., histoplasmosis) Granulomatosis with polyangiitis Idiopathic pulmonary fibrosis Hypersensitivity pneumonitis Asthma Diagnosis of berylliosis is based on history of beryllium exposures, documented beryllium sensitivity, and granulomatous inflammation on lung biopsy. Given the invasive nature of a lung biopsy, diagnosis can also be based on clinical history consistent with berylliosis, abnormal chest x-ray or CT scan findings, and abnormalities in pulmonary function tests. The radiologic and pathologic features of berylliosis are very similar to sarcoidosis. Due to the strong clinical and histopathological resemblance of sarcoidosis and berylliosis, patients are sometimes misdiagnosed with sarcoidosis until the history of exposure to beryllium is elicited and beryllium hypersensitivity demonstrated with specific testing. Some studies suggest that up to 6% of all cases of sarcoidosis are actually berylliosis. The beryllium lymphocyte proliferation test (BeLPT) is the standard way of determining sensitivity to beryllium. The test is performed by acquiring either peripheral blood or fluid from a bronchial alveolar lavage, and lymphocytes are cultured with beryllium sulfate. Cells are then counted and those with elevated number of cells are considered abnormal. Those exposed persons with two abnormal BeLPT tested with peripheral blood, or one abnormal and one borderline result, are considered beryllium sensitized.
=== Weight loss === Excess body weight is thought to be an important cause of sleep apnea. People who are overweight have more tissues in the back of their throat which can restrict the airway, especially when sleeping. In weight loss studies of overweight individuals, those who lose weight show reduced apnea frequencies and improved apnoea–hypopnoea index (AHI). Weight loss effective enough to relieve obesity hypoventilation syndrome (OHS) must be 25–30% of body weight. For some obese people, it can be difficult to achieve and maintain this result without bariatric surgery.
Sources: en.wikipedia.org
Thirlby's Anderson was also highlighted, such as by Berkshire for carrying the film's emotional story and said, "one of the film's true thrills comes in watching Thirlby effortlessly balance the conflict between a Judge's merciless duties and a psychic's compassionate understanding." The New Statesman's Laura Sneddon noted that Dredd passed the Bechdel test, lacking in sexism or misogyny and positively portraying female characters who are no weaker, more sexualised or shown less than their male counterparts. Sneddon described Anderson as repeatedly shown to have power over men who underestimate her, while Ma-Ma displays more intelligence and sadism than any of her male gang members, and neither woman interacts with the other on the basis of their gender. Many US newspaper critics were less taken with the film. Mark Olsen of the Los Angeles Times called it "a clunk-headed action picture" that "simply becomes a monotonous series of bad-guy confrontations". Frank Lovece of Newsday described it as a "soullessly gritty" film, which apart from one believable scene involving Thirlby, is "all tough-guy talk and humorless cynicism". Stephen Whitty of The Star-Ledger called it a "gray and ugly film", said that there was little to draw viewers in, and wrote that apart from the drug-induced slow-motion sequences, the film offers nothing new.
Sequest (often stylized as SEQUEST) is a tandem mass spectrometry data analysis program used for protein identification. Sequest identifies collections of tandem mass spectra to peptide sequences that have been generated from databases of protein sequences.
DNP raises energy expenditure by 30 to 40 percent and causes a weight loss of 0.7–0.9 kilograms (1.5–2.0 lb) per week. Although DNP is no longer in clinical use as a weight loss drug due to its dangerous side effects, its mechanism of action remains under investigation as a potential approach for treating obesity and non-alcoholic fatty liver disease. Researchers developed a prodrug, HU6, which is metabolized to DNP in the liver to provide more stable blood concentrations. HU6 completed a phase II trial in which it produced significant reductions in liver fat and body weight in overweight people with elevated liver fat, without serious adverse effects. DNP is used by bodybuilders, fitness enthusiasts, and people with an eating disorder to lose weight. The user profile is similar to that of anabolic steroids; many perceive it to be effective and with manageable risks. Despite health warnings from regulators, DNP is readily available online sometimes under other names such as Dinosan, Dnoc, Solfo Black, Nitrophen, Aldifen, and Chemox. DNP is often sold in tablets containing 100 to 200 mg and may be sold alongside other substances such as anabolic steroids and thyroxine. It may also be found as a contaminant in other bodybuilding supplements not advertised as containing DNP. Online message boards provide information on dosage and regimens for DNP use, and describe the risks of taking the compound and provide advice on how to mitigate hyperthermia. According to a study published in 2023, the most commonly reported doses were between 150 to 300 mg/d.
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.
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.