Everything below concerns melanocortin receptors. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-05-07. Numbers and descriptions here follow the published literature rather than marketing material.
Reversed-phase high-performance liquid chromatography is the routine method for purity assessment. Peptides absorb near 214 nm because of the peptide bond, and a gradient of acetonitrile in water separates the intact peptide from deletion sequences, oxidised products, and earlier-eluting fragments at neutral pH. Electrospray ionisation mass spectrometry provides an orthogonal check: the measured mass must agree with the theoretical value. Amino acid analysis and peptide mapping confirm structure but are used less often. Reference standards remain scarce because the peptide is not described in any pharmacopoeia.
Regulatory treatment varies by country. In the United States the peptide is not approved as a medicine, and products offered for human use may be treated as unapproved new drugs; some states also restrict sale. Australia, the United Kingdom, and European Union member states apply comparable restrictions to unapproved peptide products. Border agencies have seized shipments labelled as research chemicals. Classification may change over time, and the legal position for personal importation is not clearly settled in most published guidance.
Lyophilised melanotan-2 is supplied as a solid, which is more stable than a solution. The material is hygroscopic, so weighing is done quickly, in low humidity, with the container kept sealed. Reconstitution usually uses water for injection or bacteriostatic water, added down the wall of the vial to limit foaming. A reconstituted solution is held at 2 to 8 °C and kept away from light. Repeated freezing and thawing of the same vial is avoided because ice crystal formation and concentration effects degrade the peptide.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Lyophilised storage | −20 °C, dry, protected from light | Vials are sealed and allowed to reach room temperature before opening |
| Reconstituted storage | 2 to 8 °C, protected from light | Short-term holding; avoid repeated freeze-thaw cycles |
| Reconstitution solvent | Water for injection or bacteriostatic water | Added slowly along the vial wall to reduce foaming and shear |
| Purity measurement | RP-HPLC with area normalisation | Acetonitrile-water gradient monitored at roughly 214 nm |
| Identity confirmation | Electrospray ionisation mass spectrometry | Observed mass compared against the calculated peptide mass |
Reported observations after unregulated use include shifts in skin pigmentation and, in some accounts, unintended changes to moles and other lesions. Whether these outcomes are causally linked to the compound, and how often they occur, remain open questions because controlled data are scarce. The absence of standardised dosing and verified product purity complicates interpretation. Researchers have called for better surveillance and analytical characterisation of samples obtained outside regulated channels. Conclusions drawn from anecdotal evidence should be treated as provisional.
Melanotan-2 has not received marketing authorisation from major regulatory agencies for any therapeutic indication. Several jurisdictions classify it as a prescription-only medicine or a controlled substance when supplied for human use. Because approved products do not exist, material sold online usually sits outside pharmaceutical supply chains and formal quality oversight. Regulators have issued public notices describing the compound as unapproved. Enforcement varies, and the legal position differs between countries, which complicates any single general statement about its status.
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.
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.
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.
== Discovery == An in silico search for potential small open-reading-frames (sORFs) within 16S ribosomal RNA-encoding short peptides (20–40 amino acids) was conducted in the Pinchas Cohen lab at University of Southern California. Six sequences encoding 20–38 amino-acid-long peptides were identified, which were named SHLP 1–6. The endogenous SHLPs were detected by immunoblots and their transcripts were validated by both qPCR and northern blot.
== Mechanism == After iterative computational and experimental studies, the internal amidate mechanism was proposed in collaboration of Wu, Yu, and Houk. In the proposed mechanism, the trimeric Pd-precatalyst converts to the mono-Pd complex with coordination to solvent and the bidentate MPAA ligand. Mass spectrometry results reveal this active catalyst which forms favorably with the stabilizing dianionic MPAA ligand as computations suggest.
== Cultivation == The climbing varieties are valued for their ability to scramble up walls, fences, and other structures, and also to grow through other plants, such as shrubs and trees. Some can be trained along the ground to provide cover. Because of their adaptability and masses of spectacular flowers, clematis are among the most popular of all garden plants. Many choice and rare cultivars are to be had from mail order and online catalogues. Specialists regularly put on displays in national flower shows such as the Chelsea Flower Show. In theory, it is possible to have a clematis in flower at any time throughout the year. Many varieties provide a second period of interest with a flush of flowers, or decorative seed heads. They will grow in any good garden soil. The roots usually require a moist, cool substrate, while the herbage can take full sun. Some more delicate cultivars such as 'Nelly Moser' do better in light shade. Many clematis can be grown successfully in containers.
=== OS Fund === In October 2014, Johnson announced the launch of the OS Fund, which invests in early-stage science and technology companies and which he backed with $100 million of his personal capital.
In 1949, Glenn T. Seaborg, who devised the actinide concept, predicted that element 103 (lawrencium) should be the last actinide and that the Lr3+ ion should be about as stable as Lu3+ in aqueous solution. It was not until decades later that element 103 was finally conclusively synthesized and this prediction was experimentally confirmed. Studies on the element, performed in 1969, showed that lawrencium reacts with chlorine to form a product that was most likely the trichloride, LrCl3. Its volatility was found to be similar to the chlorides of curium, fermium, and nobelium and much less than that of rutherfordium chloride. In 1970, chemical studies were performed on 1500 atoms of 256Lr, comparing it with divalent (No, Ba, Ra), trivalent (Fm, Cf, Cm, Am, Ac), and tetravalent (Th, Pu) elements. It was found that lawrencium coextracted with the trivalent ions, but the short half-life of 256Lr precluded a confirmation that it eluted ahead of Md3+ in the elution sequence. Lawrencium occurs as the trivalent Lr3+ ion in aqueous solution and hence its compounds should be similar to those of the other trivalent actinides: for example, lawrencium(III) fluoride (LrF3) and hydroxide (Lr(OH)3) should both be insoluble in water. Due to the actinide contraction, the ionic radius of Lr3+ should be smaller than that of Md3+, and it should elute ahead of Md3+ when ammonium α-hydroxyisobutyrate (ammonium α-HIB) is used as an eluant.
Sources: en.wikipedia.org
Later, in 1687 in the Philosophiæ Naturalis Principia Mathematica, Newton showed mathematically that in an elastic fluid consisting of particles at rest, between which are repulsive forces inversely proportional to their distance, the density would be directly proportional to the pressure, but this mathematical treatise does not involve any Mariott temperature dependence and is not the proper physical explanation for the observed relationship. Instead of a static theory, a kinetic theory is needed, which was developed over the next two centuries by Daniel Bernoulli (1738) and more fully by Rudolf Clausius (1857), Maxwell and Boltzmann. This law was the first physical law to be expressed in the form of an equation describing the dependence of two variable quantities.
== Detroit Lions == It has been said that Detroit Lions' announcer Van Patrick applied the nickname "Fearsome Foursome" to the Lions front four as early as 1960, when the Lion defensive line consisted of ends Bill Glass and Darris McCord, and tackles Alex Karras and Roger Brown. Other reports state that sportswriter Bruno Kerns of the Pontiac Press first used the Fearsome Four nickname for the Lions' defensive line in 1960. The Fearsome Foursome name for the Lions' defensive line continued after Sam Williams replaced Glass in 1962; Glass being traded to the Cleveland Browns for quarterback Milt Plum after the 1961 season. Other than 1963, McCord, Karras, Brown and Williams started together from 1962 through 1965; until Williams was taken by the Atlanta Falcons in the 1966 expansion draft. Karras missed the 1963 season as he was suspended in connection with alleged gambling. Their most well-known game was the 1962 "Thanksgiving Day Massacre" game against the Green Bay Packers, where they sacked Bart Starr 11 times (seven by Brown) and broke the Packers 12-game winning streak. The group's early defensive coordinator was future Pro Football Hall of Fame head coach Don Shula. Karras is in the Pro Football Hall of Fame. The 6 ft 5 in (1.96 m) 300 pound (136 kg) Brown, was one of the first NFL lineman to play at 300 pounds or more, with the speed and agility to make him highly effective at that weight. Brown was named to the Pro Bowl as a Lion from 1962 through 1966 and first-team All-Pro twice (1962-63).
In 2005, James co-authored a paper that suggested N-acetylcysteine and glutathione ethyl ester might be useful as prophylactics for those receiving vaccines containing the preservative thiomersal. This suggestion was based on an in-vitro study in which human neuroblastoma and glioblastoma cells were directly exposed to high levels of thiomersal with and without doses of N-acetylcysteine, glutathione ethyl ester and other test substances. It is scientific consensus that the thiomersal used as a preservative in vaccines is not harmful.
=== Medical use === Hemocyte extracts from horseshoe crabs are commonly used in drug and medical device testing for these coagulative properties. Clotting indicates that endotoxins are present in the product.
The first 7-Eleven store in Denmark was opened at Østerbro in Copenhagen on September 14, 1993. There are 185 stores, mostly in Copenhagen, Aarhus, Aalborg, and Odense, including two stores at Copenhagen Central Station. In Denmark, 7-Eleven had an agreement with Shell, with a nationwide network of Shell/7-Eleven service stations. This ended in 2024 when the national franchise operator Reitan Danmark did not renew the agreement and instead used their own brand of service station Uno-X. 7-Eleven also have an agreement with the Danish railway company DSB to have 7-Eleven stores at most S-train stations and other train stations. In 2022, 7-Eleven in Denmark suffered a widespread ransomware attack that caused all stores to temporarily close. 7-Eleven did not comply with the attacker's demands. No customer data was compromised in the attack. The three biggest 7-Eleven stores in terms of revenue in the world, are all located in Denmark. The top two stores are both located at Copenhagen Central Station and the third are located at Copenhagen Airport beyond security.
Sources: en.wikipedia.org
=== Preservation === Archaeological work at Flag Fen is ongoing. Extensive drainage of the surrounding area, which benefits agriculture, means that many of the timbers are drying out and are threatened with destruction by such exposure. One section of poles is being preserved by replacing the cellulose in the wood with water-carried wax, impregnating the wood over the years. This technique is also being used to preserve Seahenge and the Hassholme Boat. Another preservation technique used for timbers found at the site is freeze drying. A well-organised visitor centre, the Flag Fen Bronze and Iron Age Centre, has been constructed there with a museum and exhibitions. In the preservation hall one section of the timbers is preserved in situ and prevented from drying out by misting with water. Also at the site are reconstructions of two Bronze Age roundhouses and one from the Iron Age. A section of the Roman road known as the Fen Causeway has been exposed and crosses the site. In addition there is a reconstruction of a prehistoric droveway used for moving livestock.
Glucagon binds to the glucagon receptor, a G protein-coupled receptor, located in the plasma membrane of the cell. The conformation change in the receptor activates a G protein, a heterotrimeric protein with αs, β, and γ subunits. When the G protein interacts with the receptor, it undergoes a conformational change that results in the replacement of the GDP molecule that was bound to the α subunit with a GTP molecule. This substitution results in the releasing of the α subunit from the β and γ subunits. The alpha subunit specifically activates the next enzyme in the cascade, adenylate cyclase.
Progesterone levels in the blood were found to be lower in those who had higher weight and higher BMI among those who became pregnant through in vitro fertilization. Current data shows that micronized progesterone, which is chemically identical to the progesterone produced in the human body, in combination with estrogen in menopausal hormone therapy does not seem to have significant effects on venous thromboembolism (blood clots in veins) and ischemic stroke (lack of blood flow to the brain due to blockage of a blood vessel that supplies the brain). However, more studies need to be conducted to see whether or not micronized progesterone alone or in combined menopausal hormone therapy changes the risk of myocardial infarctions (heart attacks). There have not been any studies done yet on the effects of micronized progesterone on hair loss due to menopause. Despite suggestions for using hormone therapy to prevent loss of muscle mass in post-menopausal individuals (age 50+), menopausal hormone therapy involving either estrogen alone, or estrogen and progesterone combined, has not been found to preserve muscle mass. Menopausal hormone therapy also does not result in body weight reduction, BMI reduction, or change in glucose metabolism.
Misoprostol can also be used to induce termination of pregnancy. It can be used on its own or following administration of mifepristone. Misoprostol may be used to terminate a pregnancy; typically only in the first trimester. Later abortions are less common and are usually performed surgically, at least in the United States. For first-trimester abortion, it is dissolved in the cheek or under the tongue; for later abortions, it can also be given as a vaginal suppository. Misoprostol may also be used to ripen the cervix in preparation for surgical abortion. Misoprostol is given orally for the treatment of ulcers. It interacts with prostaglandin receptors in the stomach to reduce secretion of stomach acids. It increases the production of gastric mucus, which forms a protective coating against stomach acid. Finally, misoprostol encourages the production of bicarbonate, which is a base that counteracts stomach acid. The medication can also protect against stomach ulcers in people who take NSAIDs such as ibuprofen on a daily basis. Misoprostol can cause nausea, stomach pain, and stomach cramps. In rare cases, it may lead to uterine rupture, which requires immediate emergency surgery.
Sources: en.wikipedia.org
Low temperature slows hydrolysis and oxidation, the two main routes by which the peptide backbone and side chains are modified. A lyophilised powder stored at −20 °C is more stable than one kept at room temperature, and once the material is dissolved the degradation rate rises, making refrigeration more important.
Liquid chromatography coupled to mass spectrometry is the most common approach because it combines a retention time with a mass measurement. A chromatographic peak alone cannot establish which peptide is present, so mass determination or amino acid analysis is used as an orthogonal confirmation alongside the separation.
This depends on buffer, pH, and concentration, and published stability data for this peptide are limited. In practice laboratories work through a refrigerated solution within a few weeks and discard samples that show cloudiness or visible particles. Freezing and thawing repeatedly is generally discouraged.
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.