If you have been reading about melanocortin receptors and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2025-09-20. Where a claim depends on a specific study, the study is described rather than over-claimed.
Research interest has centred on photoprotection and pigmentation, with a smaller body of work on appetite and sexual function. Published human data remain limited to small, frequently uncontrolled studies, and the compound has never received marketing approval from a national medicines regulator. Most laboratory work treats it as a pharmacological tool for probing melanocortin signalling in cell culture or animal models. Whether pigmentation changes observed in people translate into measurable protection against ultraviolet-induced DNA damage remains an open question.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, the naturally occurring peptide involved in pigmentation signalling. Its sequence is conventionally written as Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, with a lactam bridge joining the aspartate side chain to the lysine side chain. The empirical formula is C50H69N15O9 and the monoisotopic mass lies near 1023.5 daltons. N-terminal acetylation and the D-configured phenylalanine both increase resistance to enzymatic breakdown compared with the parent hormone.
Pharmacologically, melanotan-2 behaves as a non-selective agonist across the melanocortin receptor family. Binding at MC1R on dermal melanocytes promotes eumelanin synthesis, which underlies the tanning response described in early human work. Activity at the centrally expressed MC4R receptor is associated with reported effects on appetite and erectile function. Because the peptide does not discriminate strongly among receptor subtypes, attributing any single observed effect to one receptor pathway is generally not possible without selective antagonists or receptor knockout models.
Melanotan-2 appears on the World Anti-Doping Agency prohibited list within the peptide hormone class, and several national regulators treat it as an unapproved prescription substance. Some countries restrict importation or sale for personal use. Because the compound is widely traded as a research chemical, the practical legal picture differs between jurisdictions and shifts over time. Human safety data covering long periods are limited, and whether repeated pigmentation changes carry any lasting risk to melanocytes remains an open question.
Freeze-dried melanotan-2 is normally kept as a desiccated powder at minus twenty degrees Celsius or lower, shielded from light and moisture. Peptides of this size degrade through hydrolysis, oxidation and deamidation, and each pathway accelerates as temperature and water activity rise. Repeated freeze-thaw cycles promote aggregation and loss of material, so aliquoting a stock solution before freezing is standard laboratory practice. Once dissolved, the solution is markedly less stable than the powder. In laboratory work, solutions are generally refrigerated and used within days rather than kept for months.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Melanotan II; MT-II; N-acetyl-norleucyl-cyclo[Asp-His-D-Phe-Arg-Trp-Lys] amide | Naming follows peptide convention; the numeral distinguishes it from melanotan-1 |
| Molecular formula | C50H69N15O9 | Includes the lactam bridge; no counter-ion assumed |
| Monoisotopic mass | 1023.53 Da | Free base; salts and counter-ions shift the observed value |
| Appearance | White to off-white lyophilised powder | Batch-to-batch colour variation is not itself proof of impurity |
| Typical analytical method | RP-HPLC purity determination with ESI-MS identity confirmation | Retention time alone does not establish sequence identity |
The peptide was developed during the 1980s by researchers investigating melanocortin signalling and skin pigmentation pathways. Early work focused on analogues of alpha-melanocyte-stimulating hormone that would resist enzymatic breakdown more effectively than the parent molecule. Melanotan-2 emerged from that programme as a shortened, cyclised variant. Reports describing its synthesis and receptor activity later appeared in the scientific literature. Commercial availability grew through unregulated channels rather than through pharmaceutical approval.
Structurally, Melanotan-2 retains the core recognition motif of alpha-melanocyte-stimulating hormone while adding a lactam bridge that links two side chains and constrains the molecule into a ring. This modification lowers susceptibility to enzymatic degradation. The compound acts as an agonist at melanocortin receptors, particularly subtypes associated with melanin production. Because the same receptor family influences several physiological processes, researchers note that its activity is not confined to pigmentation alone. Receptor selectivity continues to be examined in published studies.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its sequence incorporates modified residues that increase potency and extend biological activity relative to the native hormone. The compound binds receptors of the melanocortin family and is examined mainly in laboratory research. It does not occur naturally and exists only as a manufactured chemical entity produced by solid-phase synthesis.
Regulatory treatment varies by country. In the United States, melanotan-2 is not approved for any indication, and products marketed for human use fall outside the approved drug framework. Some other jurisdictions have placed it under prescription controls or listed it as a prohibited or restricted substance. Online listings frequently describe the material as a research chemical, a category that does not carry the same manufacturing and labelling requirements as approved medicines.
Solid peptide material is generally stable when kept cold and dry. Common practice is storage at -20 degrees Celsius or lower, with desiccant and protection from light. Repeated freeze-thaw cycles and exposure to moisture are associated with degradation, aggregation, or loss of material. Once dissolved, stability depends on solvent, concentration, and temperature, and solutions are usually treated as short-lived unless stability data support longer periods. Handling notes typically emphasise minimising time at ambient temperature.
== Retail supplements == Pre-workout supplements are sold in a variety of retailers. The top-selling brands of pre-workout supplements in 2019 included Pre JYM Pre Workout by JYM Supplemental Science, ENGN Shred Pre Workout by EVLUTION Nutrition, and C4 Original Pre Workout by Cellucor. These brands were the top three in the overall bestseller category on leading bodybuilding informational website bodybuilding.com and Sports Illustrated. Some variations on common pre-workout products include sugar-free, creatine-free and stimulant-free options. The market size for pre-workout products was a $2.7 billion industry in 2008. In 2022 the market size for pre-workout had grown to $14.2 billion. Lack of regulation can mean that the ingredients used to prepare the product may not be of high quality and purity. This can mean the dose stated on the ingredients does not match the actual composition of the blend. Plant extracts in particular are often adulterated or of varying quality, but may be assumed by manufacturers to be pure and consistent. Also, protein powders used to prepare the blend may sometimes be contaminated with melamine, a plastic precursor which is sometimes added to produce false positive results for nitrogen content. Up to 50% of pre-workout blends analysed in one study were found to be contaminated with melamine.
== Etymology == The term Sensex was coined by Deepak Mohoni, a stock market analyst in 1989. BSE Sensitive Index then was at about 750 points. Sensex is a portmanteau of the words Sensitive and Index.
Early European alchemists gave sulfur an alchemical symbol of a triangle atop a cross (🜍). Another type of sulfur mentioned in alchemy, black sulfur (sulfur nigrum), also had its own symbol combining a two-barred cross atop a lemniscate (🜏). This symbol was later used by Anton LaVey as a satanist symbol, the "Leviathan cross", as he associated it with the brimstone of Hell. This has led to some confusion and misconceptions about its original alchemical meaning: in alchemical texts, black sulfur was not a synonym for "brimstone" or an alternative symbol for sulfur as one of the Three Primes, but was instead considered a distinct type of sulfur, listed separately. Black sulfur, also known as grey sulfur (sulfur griseum) or "horse brimstone" (sulfur caballinum), was a grey, impure form of sulfur, usually the dregs of sulfur purification, which was used for medicinal purposes despite often containing arsenic. Iron shavings or hammerscale were sometimes added to it in its manufacture. The "horse" in the name is thought to reference its veterinary use: low quality sulfur, only fit to treat horses. In the 19th century, it was sometimes also sold under the name "sulphur of ivy" (a corruption of sulfur vivum) and used on hops.
== Structural architectures of proteins with β-sheets == β-sheets are present in all-β, α+β and α/β domains, and in many peptides or small proteins with poorly defined overall architecture. All-β domains may form β-barrels, β-sandwiches, β-prisms, β-propellers, and β-helices.
==== Type II antithrombin deficiency ==== Type II antithrombin deficiency is characterized by normal antithrombin levels but reduced antithrombin activity in the blood of affected individuals. It was originally proposed that type II deficiency be further divided into three subgroups (IIa, IIb, and IIc) depending on which antithrombin functional activity is reduced or retained.
Sources: en.wikipedia.org
Ugandan cuisine consists of traditional and modern cooking styles, practices, foods and dishes in Uganda, with English, Arab, and Asian (especially Indian) influences. Many dishes include various vegetables, potatoes, yams, bananas and other tropical fruits. Chicken, pork, fish (usually fresh, but there is also a dried variety, reconstituted for stewing), beef and goat are all commonly eaten, although among the rural poor, meats are consumed less than in other areas, and mostly eaten in the form of bushmeat. Nyama is the Luganda language word for "meat".
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Other studies have suggested that perchlorate can also be formed by lightning activated oxidation of chloride aerosols (e.g., chloride in sea salt sprays), and ultraviolet or thermal oxidation of chlorine (e.g., bleach solutions used in swimming pools) in water.
Noboa has adopted a militarized approach to crime in Ecuador, frequently invoking states of emergency, expanding the military role in internal security, weakened judicial institutions, and raising human rights concerns. Supporters say his approach has helped to fight crime. Critics say Noboa is an autocrat, and accuse him of human rights violations, centralization of power and undermining press freedom.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, containing seven amino acids with a lactam ring and a D-configured phenylalanine residue. It is supplied as a lyophilised powder for laboratory research.
The natural hormone is a linear tridecapeptide that is rapidly degraded in circulation. Melanotan-2 is shortened, cyclised, N-terminally acetylated, and carries a D-amino acid substitution, all of which slow enzymatic breakdown.
No national medicines regulator has approved melanotan-2 for therapeutic or cosmetic use. In several jurisdictions it is treated as an unapproved prescription medicine, and its legal classification differs from country to country.
The lyophilised solid is best kept cold, dry and dark, typically at minus twenty degrees Celsius. Moisture and repeated warming cycles are the main causes of degradation. Solutions prepared from the powder are less stable and are normally used quickly.