A practical reference on Melanotan II: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-11-02 and is reviewed periodically as new material appears.
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.
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.
Quality assessment of research-grade peptide rests mainly on reversed-phase high-performance liquid chromatography for purity and on mass spectrometry for identity confirmation. A single main peak above a stated threshold, commonly ninety-eight percent by peak area, is the usual release criterion applied by suppliers. Independent analyses commissioned by laboratories and consumer organisations have repeatedly reported discrepancies between label claims and measured content, including truncated sequences, residual trifluoroacetate, and lower-than-declared peptide mass. Those findings do not establish that every supplier is unreliable, but they indicate that purity figures printed on a vial are claims requiring verification rather than settled facts.
Regulatory treatment varies by jurisdiction and has changed over time. In several countries the peptide is handled as an unapproved prescription medicine, and import or sale for human use is restricted, while elsewhere it falls under poisons or controlled-substance schedules. Enforcement activity against online vendors has been reported in Australia, New Zealand, the United Kingdom and the United States. Scholarly writing discusses melanotan-2 chiefly as an experimental tool and as a case study in unregulated peptide supply, and its precise legal position in any given country should be checked against current national schedules.
| 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 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.
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.
Regulatory status varies by jurisdiction, and the substance is frequently described as unapproved for therapeutic use. Some authorities classify it alongside prescription-only medicines or controlled categories, while others address it through general consumer protection rules. Analytical surveys have reported mismatches between label claims and measured content in products sold online, although the scope of such testing is limited. Whether these discrepancies are widespread remains an open question. Discussion in the literature therefore tends to combine chemistry, supply-chain observation and policy analysis.
The material is commonly handled as a lyophilized powder in sealed vials. The solid dissolves readily in water and in polar organic solvents, producing a clear solution after reconstitution. Light, heat and repeated freeze-thaw cycles are the concerns most often raised in handling guidance, because peptide bonds and the constrained ring can degrade. Working solutions are generally prepared fresh, and material left in solution is treated as less stable than the dry form. These properties shape how laboratories store and aliquot reference material.
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.
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.
== Contraindications == Methylergometrine is contraindicated in patients with hypertension and pre-eclampsia. It is also contraindicated in HIV positive patients taking protease inhibitors, delavirdine, and efavirenz (which is also an agonist at the 5-HT2A–mGlu2 receptor protomer and increases the chances of a patient experiencing hallucinations during methylergometrine therapy).
== Conferences == In May 2010, the Foundation sponsored a conference on "Creatine in Health, Medicine and Sport", held at Downing College, Cambridge. This was followed by the first Macular Carotenoids Conference also held at Downing College in July 2011 which led to a book, Carotenoids and Retinal Disease. Further conferences on Macular Carotenoids at Downing College were held in 2013 and 2015. The BON (Brain and Ocular Nutrition) Conference is to be held 11–13 July 2018 again at Downing College, Cambridge.
C-reactive protein (CRP), a marker of systemic inflammation, is also increased in obstructive sleep apnea (OSA). CRP and interleukin-6 (IL-6) levels were significantly higher in patients with OSA compared to obese control subjects. Patients with OSA have higher plasma CRP concentrations that increased corresponding to the severity of their apnea-hypopnea index score. Treatment of OSA with CPAP (continuous positive airway pressure) significantly alleviated the effect of OSA on CRP and IL-6 levels.
Insoluble accumulations of β-amyloid peptide in brain regions related to memory and cognition are a defining characteristic of Alzheimer's disease (AD). SNX8 has a neuroprotective role related to AD: it enhances the non-amyloidogenic APP pathway and, hence, reduces the Aβ plaques and deposit accumulations and suppresses cognitive impairment caused by AD. Some studies found that SNX8 levels were drastically lower in patients with AD. Furthermore, it has been demonstrated that SNX8 overexpression mediated by adeno-associated virus (AVV) reduced Aβ levels and reversed cognitive impairment in AD mice. It is also important mentioning that a pair of polymorphisms (rs2286206 and rs10249052) within the human SNX8 gene locus have also been associated with late-onset AD.
Sources: en.wikipedia.org
== Personal life == Guillaume was married twice; first to Marlene Williams in 1955, with whom he had two sons. Guillaume's daughter was born in 1980. They divorced in 1984. He married Donna Brown in 1986. The couple had a daughter. He also fathered a daughter by a different mother, who was born in 1950. In 1999, Guillaume suffered a stroke while working on Sports Night at Walt Disney Studios in Burbank, California. The stroke was minor, causing relatively slight damage and little effect on his speech. After six weeks in the hospital, he underwent therapy consisting of walks and gym sessions.
5 September – Astronomers identify a vast, bubble-like structure known as Hoʻoleilana in the distribution of relatively nearby galaxies, estimated at 1 billion light-years in diameter and described as the first observation of an individual baryon acoustic oscillation. 6 September The discovery of specialized astrocytes that mediate glutamatergic gliotransmission in the central nervous system is announced. Geologists report the discovery of what may be the largest known deposit of lithium, located in the crater of a dormant volcano along the Nevada–Oregon border, and estimated to contain 20 to 40 million tonnes of the metal. 7 September A university reports a study (24 Aug) that builds a theory linking a reduction in prey size in the Paleolithic to the evolution of technologies and cognitive abilities as they had to change their behaviors, abilities, weapons, and strategies. An NSF review on sleep provides the first consensus statement with data and preliminary observational studies-based conclusions on the importance of sleep timing regularity regarding health and performance. 11 September – The James Webb Space Telescope detects carbon dioxide and methane in the atmosphere of K2-18b, a potentially habitable exoplanet around 8.6 times the mass of Earth. Webb's data suggests that it might be a hycean planet covered in oceans of water, with a hydrogen-rich atmosphere.
=== Cuisine === Ghanaian cuisine includes an assortment of soups and stews with varied seafoods; most Ghanaian soups are prepared with vegetables, meat, poultry or fish. Fish is in the diet with tilapia, roasted and fried whitebait, smoked fish and crayfish, all being components of Ghanaian dishes. Banku (akple) is a starchy food made from ground corn (maize), and cornmeal based staples kɔmi (kenkey) and banku (akple) may be accompanied by some form of fried fish (chinam) or grilled tilapia and a spicy condiment made from raw red and green chillies, onions and tomatoes (pepper sauce). Banku and tilapia is a combo served in some restaurants. Fufu is the most common exported Ghanaian dish and is a delicacy across the African diaspora. Rice is an established staple meal across the country, with various rice-based dishes serving as breakfast, lunch and dinner, the main variants are waakye, plain rice and stew (either kontomire or tomato gravy), fried rice and jollof rice.
=== Microtemplate polymerization === The addition of a monomer precursor solution and crosslinking agent to a microtemplate, or mold-type device, can initiate polymerization and the formation of nanogels. This method can be used to create nanogels in specific shapes and load them with various small molecules. Lithographic microtemplate polymerization is a similar process that uses a photoinitiator and light to trigger the formation of nanogels. Lithographic microtemplate polymerization can produce smaller nanogels on a length scale of <200 nm, which has a higher resolution compared to microtemplate polymerization that does not require a photoinitiator.
=== Disassociation === Ensuring that every specimen has an individual accession number will reduce the risk of disassociation. The accession number relates that number to an identifiable object and the object can only be moved if its location is updated, ensuring the object is never disassociated from its data. Most herbaria utilize a standard system of organizing their specimens into herbarium cases. Specimen sheets are stacked in groups by the species to which they belong and placed into a large lightweight folder that is labeled on the bottom edge. Groups of species folders are then placed together into larger folders by genus. The genus folders are then sorted by taxonomic family according to the standard system selected for use by the herbarium and placed into pigeonholes in herbarium cabinets. Locating a specimen filed in the herbarium requires knowing the nomenclature and classification used by the herbarium. It also requires familiarity with possible name changes that have occurred since the specimen was collected, since the specimen may be filed under an older name. Modern herbaria often maintain electronic databases of their collections. Many herbaria have initiatives to digitize specimens to produce a virtual herbarium. These records and images are made publicly accessible via the Internet when possible.
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.
Solutions are best kept cold, protected from light, and buffered to a pH that limits hydrolysis. Dividing a stock into single-use aliquots avoids repeated freeze-thaw cycles, which measurably reduce the intact parent peak over time.