Everything below concerns melanocortin receptor. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-08-22. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms differ |
| Molecular weight | Approximately 1024 g/mol | Calculated for the free base |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water and polar solvents | Poorly soluble in non-polar solvents |
| Typical storage | -20 degrees Celsius, dry, protected from light | Refers to the solid form |
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.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry. Retention time supports identity, while the mass spectrum confirms the molecular weight of the intact peptide. Purity is frequently reported as a percentage of total peak area, a figure that depends on the wavelength, column and gradient used. Impurity profiling may also look for truncated sequences, oxidised forms and residual counterions. Amino acid analysis and peptide mapping provide orthogonal confirmation when required.
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.
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.
In tissue engineering, a highly porous artificial extracellular matrix is needed to support and guide cell growth and tissue regeneration. Natural and synthetic biodegradable polymers have been used to create such scaffolds. Simon, in a 1988 NIH SBIR grant report, showed that electrospinning could be used to produce nano- and submicron-scale polystyrene and polycarbonate fibrous mats specifically intended for use as in vitro cell substrates. This early use of electrospun fibrous lattices for cell culture and tissue engineering showed that Human Foreskin Fibroblasts (HFF), transformed Human Carcinoma (HEp-2), and Mink Lung Epithelium (MLE) would adhere to and proliferate upon the fibers. Nanofiber scaffolds are used in bone tissue engineering to mimic the natural extracellular matrix of the bones. The bone tissue is arranged either in a compact or trabecular pattern and composed of organized structures that vary in length from the centimeter range all the way to the nanometer scale. Nonmineralized organic component (i.e. type 1 collagen), mineralized inorganic component (i.e. hydroxyapatite), and many other noncollagenous matrix proteins (i.e. glycoproteins and proteoglycans) make up the nanocomposite structure of the bone ECM. The organic collagen fibers and the inorganic mineral salts provide flexibility and toughness, respectively, to ECM. Although the bone is a dynamic tissue that can self-heal upon minor injuries, it cannot regenerate after experiencing large defects such as bone tumor resections and severe nonunion fractures because it lacks the appropriate template.
=== Clotted samples === Coagulation within the sample leads to undercounting, because the analyzer samples the liquid part of the blood, while some of the platelets remain in the tube, trapped in the clot. Overfilling the sample, or inadequately mixing with anticoagulant, may allow small clots to form. Unlike platelet clumps, clots usually cannot be detected by reviewing the peripheral blood smear, but may be detected by probing with wooden sticks, including checking under the cap.
==== Adverse effects on public health ==== Public health and policy researchers at Yale University and the University of Pennsylvania sent a letter to Senate leaders warning that cuts to health programs in the bill would lead to over 51,000 preventable deaths annually.
It is home to the headquarters of three Fortune Global 500 companies, the highest in the region. The nation's best known global companies include Singapore Airlines, Changi Airport, and the Port of Singapore, all of which are among the most-awarded in their respective fields. Singapore Airlines was ranked as Asia's most-admired company, and the world's 19th most-admired company in 2015 by Fortune's annual "50 most admired companies in the world" industry surveys. Other awards it has received include the US-based Travel + Leisure's Best International Airline award, which it has won for 20 consecutive years. Changi Airport connects over 100 airlines to more than 300 cities. The strategic international air hub has more than 480 World's Best Airport awards as of 2015, and is known as the most-awarded airport in the world. Over ten free-trade agreements have been signed with other countries and regions. Singapore is the second-largest foreign investor in India. It is the 14th largest exporter and the 15th largest importer in the world.
Sources: en.wikipedia.org
=== Pharmacokinetics === A 2007 human pharmacokinetic study of sodium RLA demonstrated the maximum concentration in plasma and bioavailability are significantly greater than the free acid form, and rivals plasma levels achieved by intravenous administration of the free acid form. Additionally, high plasma levels comparable to those in animal models where Nrf2 was activated were achieved. The various forms of LA are not bioequivalent. Very few studies compare individual enantiomers with racemic lipoic acid. It is unclear if twice as much racemic lipoic acid can replace RLA. The toxic dose of LA in cats is much lower than that in humans or dogs and produces hepatocellular toxicity.
Eastern Cuba, and particularly Oriente Province, with its cultural epicentre at Santiago de Cuba, was for most of Cuba's history culturally distinct from Western Cuba and the city of Havana. Debates between Catholics, Protestants, and Secularists stirred further divisions. When the Cuban identity was being developed as distinct from a Spanish colony, hot debates between autonomists and separatists took place in the Cuban Masonic Lodges. The issue of slavery was hotly debated within all secret societies, not only in Cuba, but in the entire Caribbean and the Gulf of Mexico, and especially within the societies of Freemasonry in Latin America. Views on slavery would prove to quickly cause a strife between two very different brands of Freemasonry that developed in Cuba. The brand of Freemasonry that eventually won-over in Cuba was pro-independence and anti-slavery, conjoined with a prevailing current of Spanish liberal constitutionalism.
Debridement is an essential element of effective wound care. Although this view is deeply rooted in practice it is nonetheless based on empirical observation. Bradley et al. have stated that it is "unclear whether wound debridement is a beneficial process that expedites healing". Despite this confusing situation, current recommendation favours regular debridement. It is thought that even in an immune compromised patient debridement can assist in establishing a favourable balance of the wound bioburden.
== Further reading == Barrett, Duncan, Calvi, Nuala (2012). The Sugar Girls. Collins. ISBN 978-0-00-744847-0. Chisholm H, ed. (1911). "Sugar" . Encyclopædia Britannica (11th ed.). Cambridge University Press. Frankopan, Peter, The Silk Roads: A New History of the World, 2016, Bloomsbury, ISBN 9781408839997 Saulo, Aurora A. (March 2005). "Sugars and Sweeteners in Foods" (PDF). College of Tropical Agriculture and Human Resources. Strong, Roy (2002), Feast: A History of Grand Eating, Jonathan Cape, ISBN 0224061380
==== Image analysis ==== Both art-historical digital image processing and analog techniques have been applied to the shroud images. In 1976 scientists used imaging equipment from the American National Aeronautics and Space Administration (NASA) to analyze a photograph of the Shroud image and decoded the shroud image into a three-dimensional image. The optical physicist and former STURP member John Dee German has noted that it is not difficult to make a photograph which has 3D qualities. If the object being photographed is lit from the front, and a non-reflective "fog" of some sort exists between the camera and the object, then less light will reach and reflect back from the portions of the object that are farther from the lens, thus creating a contrast which is dependent on distance. The front image on the shroud is 1.95 metres (6 ft 5 in) long, and is not exactly the same size as the rear image, which is 2.02 metres (6 ft 8 in) long. Analysis of the images found them to be compatible with the shroud having been used to wrap a body 1.75 metres (5 ft 9 in) long. The image could be compared to oshiguma, the making of face-prints as an artform, in Japan. Furthermore, the subject's physical appearance corresponds to Byzantine iconography. The Shroud cloth is composed of threads of a nominal diameter of 0.15 mm, woven with fibers of linen with a diameter of about 10-20 μm. The Shroud image is a faint and superficial image caused by a translucent and discontinuous yellow discoloration of the fibers.
Sources: en.wikipedia.org
No. Melanotan-2 is manufactured synthetically. The naturally occurring peptide in the same family is alpha-melanocyte-stimulating hormone, which the body produces as part of normal endocrine and neural signalling.
Both are synthetic analogues derived from the same parent hormone. Reference descriptions usually characterise afamelanotide as more selective for the MC1R subtype, whereas melanotan-2 is reported to interact with a wider range of melanocortin receptors.
Early studies explored melanocortin signalling and pigmentation, which later led to informal use of the label tanning peptide. That label is not a regulatory category and does not imply approved status for any purpose.
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.