Melanotan II is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-01-05. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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 |
|---|---|---|
| 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 |
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.
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.
== External links == 5-lipoxygenase-activating+protein at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Human ALOX5AP genome location and ALOX5AP gene details page in the UCSC Genome Browser.
ASTM D482: Standard Test Method for Ash from Petroleum Products; ISO 6245: Petroleum products — Determination of ash; ASTM D874: Standard Test Method for Sulfated Ash from Lubricating Oils and Additives; ASTM D3174: Standard Test Method for Ash in the Analysis Sample of Coal and Coke from Coal; ISO 1171: Solid mineral fuels — Determination of ash; ISO 18122: Solid biofuels — Determination of ash content; ASTM D1102: Standard Test Method for Ash in Wood; ASTM D2974: Standard Test Methods for Determining the Water (Moisture) Content, Ash Content, and Organic Material of Peat and Other Organic Soils; ASTM D2866: Standard Test Method for Total Ash Content of Activated Carbon; ISO 3451: Plastics — Determination of ash — Part 1: General methods; ASTM D2584: Standard Test Method for Ignition Loss of Cured Reinforced Resins; and ASTM D5630: Standard Test Method for Ash Content in Plastics.
There was concern about the possibility of arsenic from embalmed bodies contaminating ground water supplies, as well as legal concerns that people suspected of murder by arsenic poisoning might claim that levels of poison in the deceased's body were the result of post-mortem embalming, not homicide. In 1855, the Russian chemist Alexander Michailowitsch Butlerow discovered formaldehyde, the preservative properties of which were soon noted, and it became the foundation for modern methods of embalming. Dr Frederic Ruysch was the first to have used the arterial injection method for embalming. His work of embalming was so nearly perfect that people thought the dead body was actually alive; however, he only used it to prepare specimens for his anatomical work.
== Inhibitors == Due to the similarity of the structures of IGF-1R and the insulin receptor (IR), especially in the regions of the ATP binding site and tyrosine kinase regions, synthesising selective inhibitors of IGF-1R is difficult. Prominent in current research are three main classes of inhibitor:
Sources: en.wikipedia.org
Matt Lenoe described the "revisionist school" as representing those who "insisted that the old image of the Soviet Union as a totalitarian state bent on world domination was oversimplified or just plain wrong. They tended to be interested in social history and to argue that the Communist Party leadership had had to adjust to social forces." These "revisionist school" historians challenged the "totalitarian model", as outlined by political scientist Carl Joachim Friedrich, which stated that the Soviet Union and other communist states were totalitarian systems, with the personality cult, and almost unlimited powers of the "great leader", such as Stalin. It was considered to be outdated by the 1980s and for the post-Stalinist era.
It has been shown that approximately one-third of marathon runners experience dilation of the right atrium and ventricle, have elevations of cardiac troponin and natriuretic peptides, and in a smaller fraction later develop small patches of cardiac fibrosis that are the likely substrate for ventricular tachyarrhythmias and sudden death." A simple memorial gathering was held at Colorado Chautauqua in Boulder on April 6, in which friends ran up Flagstaff Mountain in Colorado and assembled on the Chautauqua park lawn to swap stories and remembrances of him. Due to True's role in the organization and production of the Copper Canyon Ultramarathon, after his death the continuation of the event was placed in doubt. The charitable organization, Norawas de Raramuri (Friends of the Running People), founded in 2009 by (in alphabetical order) Brooke Cantor, Deborah K. Kelly, Andrew Labbe, and Chris Labbe, continued to fund Rarámuri participation in the race. Between 2009 and 2013, Norawas de Rarámuri (501(c)(3)), raised and distributed approximately $40K per year, exclusively to Rarámuri communities, including exclusively Rarámuri events, other than the Copper Canyon Ultramarathon. Under new direction by Maria Walton, True's partner, and Fuego y Agua Events LLC. Director Josue Stephens, the race event continued for several more years. In honor of Micah, the race has since taken the name by which it has always been known in Mexico, Ultramaraton Caballo Blanco.
== Natural occurrences == Caffeic acid can be found in the bark of Eucalyptus globulus, the barley grain Hordeum vulgare, and the herb Dipsacus asperoides. It can also be found in the freshwater fern Salvinia molesta and in the mushroom Phellinus linteus.
Unfortunately, Chelex extraction does not yield as much quantity and the DNA yielded is single-stranded, which means it can only be used for PCR-based analyses and not for RFLP. Solid phase extraction such as using a spin-column-based extraction method takes advantage of the fact that DNA binds to silica. The sample containing DNA is added to a column containing a silica gel or silica beads and chaotropic salts. The chaotropic salts disrupt the hydrogen bonding between strands and facilitate the binding of the DNA to silica by causing the nucleic acids to become hydrophobic. This exposes the phosphate residues so they are available for adsorption. The DNA binds to the silica, while the rest of the solution is washed out using ethanol to remove chaotropic salts and other unnecessary constituents. The DNA can then be rehydrated with aqueous low-salt solutions allowing for elution of the DNA from the beads. This method yields high-quality, largely double-stranded DNA which can be used for both PCR and RFLP analysis. This procedure can be automated and has a high throughput, although lower than the phenol-chloroform method. This is a one-step method i.e. the entire procedure is completed in one tube. This lowers the risk of contamination making it very useful for the forensic extraction of DNA. Multiple solid-phase extraction commercial kits are manufactured and marketed by different companies; the only problem is that they are more expensive than organic extraction or Chelex extraction.
structural formula A graphical representation of the molecular structure and geometry of a particular chemical compound, showing how the atoms are arranged in real, three-dimensional space. Chemical bonding within the molecule is also shown, either implicitly or explicitly. When known with certainty, structural formulas are very useful because they allow chemists to visualize the molecules and the structural changes that occur in them during chemical reactions.
Sources: en.wikipedia.org
Volume, Area, Dihedral Angle Reporter (VADAR) is a freely available protein structure validation web server that was developed as a collaboration between Dr. Brian Sykes and Dr. David Wishart at the University of Alberta. VADAR consists of over 15 different algorithms and programs for assessing and validating peptide and protein structures from their PDB coordinate data. VADAR is capable of determining secondary structure (using three different algorithms), identifying and classifying six different types of beta turns, determining and calculating the strength of C=O -- N-H hydrogen bonds, calculating residue-specific accessible surface areas (ASA), calculating residue volumes, determining backbone and side chain torsion angles (phi, psi, omega and chi angles), assessing local structure quality (through numerous quality indices), evaluating global structure quality, and identifying residue "outliers" (residues with unusual structural features). The results have been validated through extensive comparison to published data and careful visual inspection. VADAR produces both text and graphical output with most of the quantitative data presented in easily viewed tables. In particular, VADAR's output is presented in a vertical, tabular format with most of the sequence data, residue numbering and any other calculated property or feature presented from top to bottom, rather than from left to right.
During his tenure with the X-Men, Wolverine becomes a mentor for Kitty Pryde and later on Jubilee. Logan again encounters Jean, who has been resurrected and re-joins the X-Men, leading to resumption of Logan's rivalry with Cyclops. He is able to recall some of the trauma he received from the Weapon X program and tries to investigate his past, although his memories remain unreliable because of brainwashing and false memory implants. He meets Maverick, another former participant in the Weapon X project, and discovers that he had previously worked together with Sabretooth in Team X. During a conflict, the supervillain Magneto forcibly removes the adamantium from Wolverine's skeleton. This massive trauma causes his healing factor to burn out and leads to the discovery that his claws are actually bone. Wolverine leaves the X-Men for a time, embarking on a series of adventures during which his healing factor returns. After his return to the X-Men, Cable's son Genesis kidnaps Wolverine and attempts to re-bond adamantium to his skeleton. This is unsuccessful and causes Wolverine's mutation to accelerate out of control. He degenerates physically and mentally into a more primitive, bestial state. Elektra helps him to recover his humanity. Eventually, the villain Apocalypse captures Wolverine, brainwashes him into becoming the Horseman of Death, and successfully re-bonds adamantium to his skeleton. Wolverine overcomes Apocalypse's programming and returns to the X-Men.
2C-EF, also known as 4-(2-fluoroethyl)-2,5-dimethoxyphenethylamine, is a psychedelic drug of the phenethylamine and 2C families. It is the 2C analogue of the DOx psychedelic DOEF. The drug is taken orally. 2C-EF was first described in the literature by Alexander Shulgin in his 1991 book PiHKAL (Phenethylamines I Have Known and Loved.
Cupuaçu is most commonly propagated from seed, but grafting and rooted cuttings are also used. Cupuaçu trees are often incorporated in agroforestry systems throughout the Amazon due to their high tolerance of infertile soils, which are predominant in the Amazon region. Cupuaçu is generally harvested from the ground once they have naturally fallen from the tree. It can be difficult to determine peak ripeness because there is no noticeable external color change in the fruit. However studies have shown that in Western Colombian Amazon conditions, fruits generally reach full maturity within 117 days after fruit set. Brazilians either eat it raw or use it in making sweets. Commercial food products include pulp and powder.
=== U.S. federal government actions === In 2002, a panel of toxicologists, including several from EPA, proposed a level of 150 ppb for drinking water in the PFOA contaminated area around DuPont's Washington Works plant. This initially proposed level was much higher than any known environmental concentration and was over 2,000 times the level EPA eventually settled on for the drinking water health advisory. In July 2004, EPA filed a suit against DuPont alleging "widespread contamination" of PFOA near the Parkersburg, West Virginia plant "at levels exceeding the company's community exposure guidelines"; the suit also alleged that "DuPont had—over a 20 year period—repeatedly failed to submit information on adverse effects (in particular, information on liver enzyme alterations and birth defects in offspring of female Parkersburg workers)." In October 2005, a USFDA study was published revealing PFOA and PFOA precursor chemicals in food contact and PTFE products. On January 25, 2006, EPA announced a voluntary program with several chemical companies to reduce PFOA and PFOA precursor emissions by the year 2015. On February 15, 2005, EPA's Science Advisory Board (SAB) voted to recommended that PFOA should be considered a "likely human carcinogen". On May 26, 2006, EPA's SAB addressed a letter to Administrator Stephen L. Johnson. Three-quarters of advisers thought the stronger "likely to be carcinogenic" descriptor was warranted, in opposition to EPA's own PFOA hazard descriptor of "suggestive evidence of carcinogenicity, but not sufficient to assess human carcinogenic potential".
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. 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.