This is a working overview of Melanotan II, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-11-07 and is reviewed periodically as new material appears.
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.
Routine characterisation relies on reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, using a C18 column and a water-acetonitrile gradient containing trifluoroacetic acid. Electrospray ionisation mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidised by-products that co-elute poorly. Sequence and stereochemistry require additional work, such as peptide mapping or amino acid analysis, because a chromatographic purity figure alone does not distinguish a diastereomer from the target peptide. Independent testing of research-grade material frequently shows measured content below the stated label, so a certificate of analysis is best read together with the method that produced it.
Melanotan-2 is handled in the laboratory as a lyophilised powder that dissolves readily in water, dimethyl sulfoxide and dimethylformamide, with limited solubility in ethanol. Stock solutions prepared in an organic solvent often precipitate when diluted into aqueous buffer, so gradual dilution with mixing is standard practice. The peptide carries a tryptophan residue and a histidine residue, both sensitive to oxidation and to alkaline conditions. Working solutions are therefore kept near neutral to slightly acidic pH, protected from light, and consumed within the same working session whenever that is practical.
Solid peptide kept dry at minus twenty degrees Celsius, shielded from light and moisture, is generally considered stable for extended periods. Solutions are divided into single-use aliquots and held at minus twenty or minus eighty degrees Celsius, because repeated freeze-thaw cycles promote aggregation and loss of material to container surfaces. Hydrolysis of the backbone and oxidation of tryptophan are the principal degradation routes in aqueous solution, and both accelerate at ambient temperature. Hygroscopic uptake after a vial is opened can also shift the actual mass weighed, which affects any concentration calculated from it.
| 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 |
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.
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.
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.
Melanocytes are the pigment-producing cells of the skin, and they carry melanocortin-1 receptors on their surface. When the receptor is activated, cyclic adenosine monophosphate rises inside the cell and raises the activity of enzymes such as tyrosinase, which increases melanin output. Melanotan-2 binds melanocortin-1 receptors in vitro and in animal models, and this binding is generally described as the basis for the tanning effect. Other receptors account for different effects: melanocortin-4 receptors contribute to appetite and erectile signalling, while melanocortin-3 and melanocortin-5 receptors contribute to energy balance and exocrine function.
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.
The first human corpse to be frozen with the hope of future resurrection was James Bedford's, a few hours after his cancer-caused death in 1967. Bedford's is the only cryonics corpse frozen before 1974 still frozen today.
=== Economic Sciences === The medal for the Nobel Memorial Prize in Economic Sciences was designed by Gunvor Svensson-Lundqvist in 1968. The obverse of the medal depicts Alfred Nobel and the words "Sveriges Riksbank till Alfred Nobels Minne 1968" ("The Sveriges Riksbank, in memory of Alfred Nobel, 1968") with the symbol of the Sveriges Riksbank, the horn of plenty, displayed below. The name of the recipient is inscribed on the edge of the medal. The reverse features the emblem of the Royal Swedish Academy of Sciences, the North Star, in a design from 1815. "Kungliga Vetenskaps Akademien" ("The Royal Swedish Academy of Sciences") is inscribed around the edge of the star. It is the only medal without a quotation on its reverse. Since 2012 the economics medal has been manufactured by Svenska Medalj in Eskilstuna.
== Etymology == In Old Japanese, me stood for edible seaweeds in general as opposed to mo standing for algae. In kanji, such as 海藻, 軍布 and 和布 were applied to transcribe the word. Among seaweeds, wakame was likely most often eaten, therefore me especially meant wakame. It expanded later to other seaweeds like kajime, hirome (kombu), arame, etc. Wakame is derived from waka + me (若布, lit. 'young seaweed'). If this waka is a eulogistic prefix, the same as the tama of tamagushi, wakame likely stood for seaweeds widely in ancient times. In the Man'yōshū, in addition to 和可米 and 稚海藻 (both are read as wakame), nigime (和海藻, soft wakame) can be seen. Besides, tamamo (玉藻, lit. 'beautiful algae'), which often appeared in the Man'yōshū, may be wakame depending on poems.
Full-fat soybean meal, made from whole soybeans. It has a high metabolizable energy concentration. (For example, metabolizable energy for swine in this product is about 3.69 megacalories (i.e. 15.4 MJ) per kg dry matter.) Crude protein concentration is about 38 percent (as fed). This kind of product is sometimes fed to various classes of livestock. Defatted soybean meal, containing no hulls. This product has an intermediate energy concentration. (For example, Balaji metabolizable energy for swine in this product is about 3.38 megacalories (i.e. 14.1 MJ) per kg dry matter.) Crude protein concentration is about 48 percent. This percentage [which is commonly used in describing the product] is calculated at the typical as-fed moisture content of 88 percent. Thus, crude protein concentration expressed on a dry matter basis is 54 percent. This product is commonly fed to swine, broilers and layers. Defatted soybean meal, containing soybean hulls. The hulls are readily digestible by ruminant livestock. This product is often fed as a protein supplement for domestic ruminants. Ruminant-metabolizable energy concentration is about 3.0 megacalories (i.e. about 12.5 MJ) per kg dry matter, and crude protein concentration is about 44 percent. The latter percentage [which is commonly used in describing the product] is calculated at the typical as-fed moisture content of 90 percent. Thus, crude protein concentration on a dry matter basis is 49 percent.
No charges have been brought against the contractor because he does not fall under military jurisdiction; it is questionable whether any charges will or even can be brought against him. Donald Rumsfeld had said that army and government had only been informed in January and not in detail. On January 16, 2004, a press release was issued by the United States Central Command (CENTCOM) stating that an investigation had been initiated in response to allegations of detainee abuse at an unspecified detention facility (now known to be Abu Ghraib prison). In March 2004, 6 soldiers in Abu Ghraib were charged with dereliction of duty, cruelty and maltreatment, and sexual abuse. 17 others were suspended from duty, including the seven U.S. officers who ran the prison. Also recommended for discipline was Brig. Gen Janis Karpinski, the commander of the 800th brigade. The Red Cross, which had access to these prisons, has stated that the instances of torture were not aberrations but were systemic. Some officers have attempted to defend themselves by saying that they were only doing their duty. In response to ongoing complaints, the US military initiated a program to reform the internment and treatment systems. The reforms are expected to increase safeguards for prisoners' rights, to ensure each prisoner receives a copy of their internment order, and has their charges explained to them within 72 hours. They additionally plan to publicly post information about detainees so that family members can know what happened to their loved ones. Reforms were made in March 2004.
Sources: en.wikipedia.org
=== Processing === The availability of wild-harvested insects can be seasonally dependent. This presents a challenge, as many wild-harvested insects have a short shelf life, sometimes of only a day or two. Identifying methods of processing and storing that extend the shelf life of seasonal insects will improve the efficiency of their harvest and consumption.
B-DNA The "standard" or classical structural conformation of the DNA double helix in vivo, thought to represent an average of the various distinct conformations assumed by very long DNA molecules under physiological conditions. The B-form double helix has a right-handed twist with a diameter of 23.7 ångströms and a pitch of 35.7 ångströms or about 10.5 base pairs per full turn, such that each nucleotide pair is rotated 36° around the helical axis with respect to its neighboring pairs. See also A-DNA and Z-DNA.
On the other hand, a mutation may occur in a somatic cell of an organism. Such mutations will be present in all descendants of this cell within the same organism. The accumulation of certain mutations over generations of somatic cells is part of cause of malignant transformation, from normal cell to cancer cell. Cells with heterozygous loss-of-function mutations (one good copy of gene and one mutated copy) may function normally with the unmutated copy until the good copy has been spontaneously somatically mutated. This kind of mutation happens often in living organisms, but it is difficult to measure the rate. Measuring this rate is important in predicting the rate at which people may develop cancer. Point mutations may arise from spontaneous mutations that occur during DNA replication. The rate of mutation may be increased by mutagens. Mutagens can be physical, such as radiation from UV rays, X-rays or extreme heat, or chemical (molecules that misplace base pairs or disrupt the helical shape of DNA). Mutagens associated with cancers are often studied to learn about cancer and its prevention.
== Hardware == In terms of input and output, ICP-MS instrument consumes prepared sample material and translates it into mass-spectral data. Actual analytical procedure takes some time; after that time the instrument can be switched to work on the next sample. Series of such sample measurements requires the instrument to have plasma ignited, meanwhile a number of technical parameters has to be stable in order for the results obtained to have feasibly accurate and precise interpretation. Maintaining the plasma requires a constant supply of carrier gas (usually, pure argon) and increased power consumption of the instrument. When these additional running costs are not considered justified, plasma and most of auxiliary systems can be turned off. In such standby mode only pumps are working to keep proper vacuum in mass-spectrometer. The constituents of ICP-MS instrument are designed to allow for reproducible and/or stable operation.
Sources: en.wikipedia.org
==== Physiological action ==== The physiological effects of labetalol when administered acutely (intravenously) are not predictable solely by their receptor blocking effect, i.e. blocking β1-adrenergic receptors should decrease heart rate, but labetalol does not. When labetalol is given in acute situations, it decreases the peripheral vascular resistance and systemic blood pressure while having little effect on the heart rate, cardiac output and stroke volume, despite its α1-, β1- and β2-adrenergic receptor blocking mechanism. These effects are mainly seen when the person is in the upright position. Long term labetalol use also has different effects from other beta blockers. Other beta blockers, such as propranolol, persistently reduce cardiac output during exercise. The peripheral vascular resistance decreases when labetalol is first administered. Continuous labetalol use further decreases peripheral vascular resistance. However, during exercise, cardiac output remains the same due to a compensatory mechanism that increases stroke volume. Thus, labetalol is able to reduce heart rate during exercise while maintaining cardiac output by the increase in stroke volume.
== External links == GeneReviews/NCBI/NIH/UW entry on Hemophilia A Factor+VIII at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Overview of all the structural information available in the PDB for UniProt: P00451 (Human Factor VIII) at the PDBe-KB.
Bohr model Also Rutherford–Bohr model. A model of the general structure of the atom proposed by Niels Bohr and Ernest Rutherford in 1913, featuring a small, dense nucleus of positively charged particles surrounded by orbiting electrons, which are attracted to the nucleus by electrostatic forces. This interpretation replaced several earlier hypotheses and quickly became the prevailing standard model for depicting atomic structure.
in the range of 108 – 1010 M−1 s−1. These enzymes are so efficient they effectively catalyse a reaction each time they encounter a substrate molecule and have thus reached an upper theoretical limit for efficiency (diffusion limit); and are sometimes referred to as kinetically perfect enzymes. But most enzymes are far from perfect: the average values of
== Awards and honors == Wilhelm Exner Medal, 1958 Johann Josef Ritter von Precht Medal of TU wien, 1965 Erwin Schrödinger Prize of the Austrian Academy of Sciences, 1970 M.S. Tswett Chromatography Award, 1974 (first year awarded) Commemorative M.S. Tswett Medal of the U.S.S.R. Academy of Sciences, 1978 Honorary degree from the Technische Universität Berlin First-class cross of the Austrian Order for Science and Art A Street in Munich was called after her (Erika-Cremer-Straße in 81829 München)
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.
Purity is normally stated as an area percentage from high-performance liquid chromatography, for example ninety-five or ninety-eight percent. That figure describes the proportion of ultraviolet-absorbing material eluting as the main peak. It says nothing about water content, counterions, residual solvents or mass fraction of the peptide itself.