Everything below concerns cyclic heptapeptide. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-01-11. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
The compound emerged from research programs in the 1980s that examined analogues of alpha-melanocyte-stimulating hormone for pigmentation and photoprotection. Investigators modified the native sequence to extend activity duration and potency. A related analogue, afamelanotide, was developed within the same broad line of inquiry and eventually gained approval in certain jurisdictions for a rare light-sensitivity condition. Melanotan-2 itself did not progress through the same regulatory route and has no approved therapeutic indication.
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.
| 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 |
Melanotan-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
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.
Melanotan-2, also written Melanotan II, is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, and the lactam bridge between the aspartate and lysine side chains constrains the peptide into a ring. This structural change increases receptor affinity and metabolic stability relative to the native hormone. The compound was created in the 1980s as a research tool for studying pigmentation biology.
==== Aqueous solutions ==== Aqueous solutions are solutions of a compound with water. In contrast to other formulations, such as oil solutions, aqueous suspensions, and emulsions, aqueous solutions of estradiol and estradiol esters by intramuscular injection are not depot injections. Instead, they are rapidly absorbed and eliminated, analogously to intravenous injections of estradiol and estradiol esters. The durations of aqueous solutions of estradiol and estradiol esters by intramuscular injection are measured in hours.
Faced with the loss of support for his government, President Rodríguez Zapatero decided to bring forward the general elections by four months, to November 2011. The People's Party won an absolute majority of 186 deputies – its best result in history – while the PSOE only managed 110 deputies – its worst result until then. The United Left coalition, led by Cayo Lara, won 11 deputies. UPyD of Rosa Díez won 5 deputies, the Basque coalition Amaiur won six seats with a program defending the right of self-determination of Euskadi, and CiU displaced the PSC as the most voted party in Catalonia. The Socialists, big losers in the elections, held the 38th Federal Congress of the PSOE in February 2012, in Seville, in which Alfredo Pérez Rubalcaba was elected secretary general by a narrow margin against Carme Chacón. On December 20, 2011, the leader of the PP Mariano Rajoy was invested as the sixth president of the Government of democracy.
== Medicine == White coats are sometimes seen as the distinctive dress of both physicians and surgeons, who have worn them for over 100 years. In the nineteenth century, respect for the certainty of science was in stark contrast to the quackery and mysticism of nineteenth-century medicine. To emphasize the transition to the more scientific approach of modern medicine, physicians began to represent themselves as scientists, donning the most recognizable symbol of the scientist, the white laboratory coat. The modern white coat was introduced to medicine in the late 1800s as a symbol of cleanliness.
== In the news == On January 5th, 2026, Nestlé issued a global recall of some batches of infant formula, due to the presence of cereulide. The cereulide was found in a Nestlé production facility in Nunspeet the Netherlands. On January 24th 2026, Danone also recalled a single batch of infant formula. The contaminated ingredient was arachidonic acid oil.
Sources: en.wikipedia.org
Masson's trichrome is a three-colour staining procedure used in histology. The recipes emerged from Claude L. Pierre Masson's (1880–1959) original formulation have different specific applications, but all are suited for distinguishing cells from surrounding connective tissue. Most recipes produce red keratin and muscle fibers, blue or green collagen and bone, light red or pink cytoplasm, and dark brown to black cell nuclei. The trichrome is applied by immersion of the fixated sample into Weigert's iron hematoxylin, and then three different solutions, labeled A, B, and C:
Krypton was discovered in Britain in 1898 by William Ramsay, a Scottish chemist, and Morris Travers, an English chemist, in residue left from evaporating nearly all components of liquid air. Neon was discovered by a similar procedure by the same workers just a few weeks later. William Ramsay was awarded the 1904 Nobel Prize in Chemistry for discovery of a series of noble gases, including krypton. In 1960, the International Bureau of Weights and Measures defined the meter as 1,650,763.73 wavelengths of light emitted in the vacuum corresponding to the transition between the 2p10 and 5d5 levels in the isotope krypton-86. This agreement replaced the 1889 international prototype meter, which was a metal bar located in Sèvres. This also made obsolete the 1927 definition of the ångström based on the red cadmium spectral line, replacing it with 1 Å = 10−10 m. The krypton-86 definition lasted until the October 1983 conference, which redefined the meter as the distance that light travels in vacuum during 1/299,792,458 s.
== Etymology == The scientific name Crotalus is derived from Ancient Greek: κρόταλον, romanized: krótalon, lit. 'castanet'. The name Sistrurus is the Latinized form of the Greek for "tail rattler" (Σείστρουρος, Seístrouros) and shares its root with the ancient Egyptian musical instrument the sistrum, a type of rattle.
== Origin == Missense mutations may be inherited or arise spontaneously, termed de novo mutations. Well studied diseases arising from inherited missense mutations include sickle cell anemia, cystic fibrosis, and early-onset Alzheimer's and Parkinson's disease. De novo mutations that increase or decrease the activity of synapses have been implicated in the development of neurological and developmental disorders, such a Autism Spectrum Disorder and intellectual delay.
=== Gel electrophoresis === Gel electrophoresis is a powerful analytical technique used to separate proteins based on their size and charge. Proteins are loaded onto a gel matrix, typically made of polyacrylamide or agarose, and an electric current is applied. The negatively charged proteins migrate towards the positive electrode, with smaller proteins moving faster through the gel matrix than larger ones. This method is crucial for assessing the purity and size of protein samples.
Sources: en.wikipedia.org
Changes in nearby tissue is not the only possible impact of ligand therapy, there may be immunologic responses from the target tissue that cause changes remotely. This has been dubbed the "abscopal effect". While this mechanism is not well understood, it explains the impact of other tissue, both benign and malignant, after targeted radiotherapy.
The act of overseeing the progress of a clinical trial, and of ensuring that it is conducted, recorded, and reported in accordance with the protocol, standard operating procedures (SOPs), GCP, and the applicable regulatory requirement(s). (ICH E6) Multicenter study
Despite these allegations, Rose stated she had loved her daughter and had no knowledge of her murder. Further questioned about the contradictory explanations she and Fred had given about Heather's disappearance, Rose claimed these discrepancies had stemmed from telephone conversations she had had with Heather after she had left home. The defence next called a succession of women who claimed to have been attacked or assaulted between 1966 and 1975 by a lone male whose physical description matched that of Fred. These seven women each testified they had recognised their attacker as Fred when his photograph was publicised in 1994. The intention of this testimony was to illustrate to the jury that Fred was capable of abducting, assaulting or attempting to attack women without Rose, which the prosecution had never disputed. The physical recollections of several of these women varied greatly. The final witness to testify at Rose's trial was Janet Leach, Fred's appointed appropriate adult, whom the prosecution had called to testify on 7 November in rebuttal of the tape recordings of Fred's confession, which had been played to the court on 3 November, in which he had stressed Rose had "known nothing at all" about the murders.
prostacyclin synthase to create prostacyclin thromboxane-A synthase to create thromboxane A2 and 12-(S)-hydroxy-5Z,8E,10E-heptadecatrienoic acid (HHT) (see 12-Hydroxyheptadecatrienoic acid) prostaglandin D2 synthase to create prostaglandin D2 prostaglandin E synthase to create prostaglandin E2 prostaglandin F synthase to create prostaglandin F2α It rearranges non-enzymatically to:
== Public figures with CMT == US country music singer Alan Jackson. Jackson was definitively diagnosed in his early 50s. US actor Julie Newmar. She played the original Catwoman in the 1960s Batman television series. US Paralympic cyclist Anthony Zahn. He won a bronze medal at the 2008 Beijing Paralympic Games. Jamaica and US fashion designer Rachel Scott, who serves as Creative Director of Proenza Schouler. UK cultural and disability studies academic Professor George McKay. His books include Shakin' All Over: Popular Music and Disability (2014). US Paralympic swimmer Jamal Hill, bronze medallist at the Tokyo 2021 Paralympic Games. US actress Isabelle Tate was reported to have died of a rare variant of the disease in 2025. Irish Paralympic cyclist Eoghan Clifford. US filmmaker and playwright Crystal R. Emery. Known for directing the 2010 documentary The Deadliest Disease in America. Australian wheelchair tennis player Jin Woodman (born 2009)
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. 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.