If you have been reading about cyclic heptapeptide 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 2026-01-30. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Published human data come mostly from small, short studies rather than large controlled trials. Reported outcomes include increased skin pigmentation and, in some reports, effects on appetite and libido, but sample sizes are small and follow-up is limited. Whether long-term use produces durable pigment changes or adverse effects is not established. Because products sold outside pharmacies are not standardized, the actual content of any given vial is often unknown. Independent testing of such material is uncommon.
Melanotan II is a synthetic cyclic heptapeptide analog derived from the core sequence of alpha-melanocyte-stimulating hormone. Researchers at the University of Arizona synthesized it during the 1980s while studying pigmentation and appetite signaling. The compound is not an approved medicine in any major jurisdiction and appears mainly in laboratory and research-chemical settings. Its structure incorporates a lactam bridge between side chains, which constrains the ring and slows enzymatic breakdown relative to the natural hormone.
Melanotan II binds several melanocortin receptor subtypes rather than a single target. MC1R on melanocytes drives melanin synthesis, while MC3R and MC4R participate in energy balance, appetite, and sexual response pathways. This lack of selectivity explains why reported effects extend beyond skin darkening. Substitutions at positions four and seven, including norleucine and D-phenylalanine, increase potency and resistance to peptidases. Understanding which receptor mediates which effect remains an active area of investigation.
| 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 |
Receptor-binding studies classify melanotan II as a non-selective melanocortin agonist. It interacts with MC1R, MC3R, MC4R and MC5R, with reported affinities in the low nanomolar range and no strong subtype preference. Activation of MC1R on dermal melanocytes shifts pigment synthesis toward eumelanin, the dark polymer deposited in melanosomes and transferred to keratinocytes. Because the same peptide engages MC4R in the hypothalamus, it also appears in animal work on food intake and erectile response, which is why it is discussed in both pigment and metabolic research. Which receptor populations dominate after systemic exposure in humans is not fully established.
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.
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.
=== Organosilanes === Organosilanes create a network of electrically charged molecules on the surface, which rupture the cell wall on contact. This is due to their structure which consists of a hydrophobic element and a cationic element. While the hydrophobic element may prevent adherence in the first place, it may also intercalate with the cell wall, whose rupture is aided by the cationic component.
==== Hadi makes inroads ==== National reconciliation talks were held with the participation of many separatist elements, as well as the Houthis. Nine years after the death of Hussein Badreddin al-Houthi, the Yemeni government turned over the remains of the Houthi patriarch to his family and he was buried in northern Yemen in June 2013, with a representative of the Hadi administration in attendance. Hadi visited the United States, a key overseas ally, in July 2013. The U.S. also lifted a ban on transferring detainees from its Guantanamo Bay detention camp in Cuba to Yemen. Meanwhile, Saudi Arabia deported as many as 300,000 to 400,000 Yemeni migrant workers to their home country during 2013, causing an influx of poor, landless Yemenis into northern Yemen.
He returned in round 7, but had a subsequent dip in form. However, Essendon coach, Matthew Knights, persisted with Jetta and was paid back by his outstanding performance against Fremantle in round 14. The 2009 season was another important year in Jetta's development. A few quiet performances in the pre-season led to his omission from the side for the opening two rounds of the season. However, strong form for the Bendigo Bombers led to a recall for Essendon's vital round 3 encounter with Carlton. On 7 September 2014, Jetta parted ways with Essendon after eight seasons with the club. Jetta, along with 33 other Essendon players, was found guilty of using a banned performance-enhancing substance, thymosin beta-4, as part of Essendon's sports supplements program during the 2012 season. He and his teammates were initially found not guilty in March 2015 by the AFL Anti-Doping Tribunal, but a guilty verdict was returned in January 2016 after an appeal by the World Anti-Doping Agency. He was suspended for two years which, with backdating, ended in February 2017; as a result, he served approximately seventeen months of his suspension and missed the entire 2016 WAFL season and parts of the 2015/16 and 2016/17 NTFL seasons. He later played with Peel Thunder in the WAFL and played for Pinjarra in the WA Amateur Football League in 2018.
Retinyl acetate (also called vitamin A acetate or all‑trans‑retinol acetate) is a synthetic, fat‑soluble acetate ester of retinol often used to supply vitamin A in food fortification, dietary supplements, and topical cosmetic products. Because the acetyl group protects the alcohol functionality, the compound is markedly more stable to heat, oxygen and light than free retinol, yet is rapidly hydrolyzed in the human intestine to active retinol after ingestion. Commercially, retinyl acetate is the second most common retinyl ester after retinyl palmitate.
Termination of elongation depends on the release factor eRF1 that recognizes all three stop codons. When a stop codon is reached, termination of the polypeptide occurs the ribosome is disassembled and the completed polypeptide is released. eRF3 is a ribosome-dependent GTPase that helps eRF1 release the completed polypeptide. The human genome encodes a few genes whose mRNA stop codons are surprisingly leaky: In these genes, termination of translation is inefficient due to special RNA bases in the vicinity of the stop codon. Leaky termination in these genes leads to translational readthrough of up to 10% of the stop codons of these genes. Some of these genes encode functional protein domains in their readthrough extension so that new protein isoforms can arise. This process has been termed 'functional translational readthrough'. When the A site of the ribosome is occupied by a stop codon (UAA, UAG, or UGA) on the mRNA, creating the primary structure of a protein. tRNA usually cannot recognize or bind to stop codons. Instead, the stop codon induces the binding of a release factor protein (RF1 & RF2) that prompts the disassembly of the entire ribosome/mRNA complex by the hydrolysis of the polypeptide chain from the peptidyl transferase center of the ribosome. Drugs or special sequence motifs on the mRNA can change the ribosomal structure so that near-cognate TRNAs are bound to the stop codon instead of the release factors. In such cases of 'translational readthrough', translation continues until the ribosome encounters the next stop codon.
Sources: en.wikipedia.org
Fast atom bombardment (FAB) is an ionization technique used in mass spectrometry in which a beam of high energy atoms strikes a surface to create ions. It was developed by Michael Barber at the University of Manchester in 1980. When a beam of high energy ions is used instead of atoms (as in secondary ion mass spectrometry), the method is known as liquid secondary ion mass spectrometry (LSIMS). In FAB and LSIMS, the material to be analyzed is mixed with a non-volatile chemical protection environment, called a matrix, and is bombarded under vacuum with a high energy (4000 to 10,000 electron volts) atomic beam. The atoms are typically from an inert gas such as argon or xenon. Common matrices include glycerol, thioglycerol, 3-nitrobenzyl alcohol (3-NBA), 18-crown-6 ether, 2-nitrophenyloctyl ether, sulfolane, diethanolamine, and triethanolamine. This technique is similar to secondary ion mass spectrometry and plasma desorption mass spectrometry.
=== ENOUGH === Funded by: Horizon 2020 (European Commission) and European Green Deal Duration: 4 years (October 2021-September 2025) Objective: The main scope of the project is to support the EU farm-to-fork sustainable strategy by providing technical, financial, and political tools and solutions to reduce GHG emissions (by 2030) and achieve carbon neutrality (by 2050) in the food industry.
Rotheca myricoides or Butterfly Clerodendrum, Butterfly Bush, and (butterfly bush – also a name for Buddleja species) is a species of flowering plant in the family Lamiaceae. It is native to tropical eastern Africa and widely cultivated elsewhere. In cultivation, it is frequently known by one of its synonyms, such as Clerodendrum myricoides. The cultivar 'Ugandense' is an untidy evergreen shrub growing to 4 m (13 ft) tall and 2.5 m (8.2 ft) broad, with oval leaves and masses of pale-violet blue butterfly-like flowers in summer and autumn. Each flower has a darker blue lower petal. With a minimum temperature of 10 °C (50 °F), this plant can only be grown under glass in temperate zones. The altitude range for this species is 900–1680 m. The plant has won the Royal Horticultural Society's Award of Garden Merit.
This procedure can induce ovulation, typically leads to a single pregnancy, but other risks may be higher compared to medication. The procedure might lead to lower chance of live births compared to medication alone. Ovarian wedge resection is no longer used as much due to complications such as adhesions and the presence of frequently effective medications. As a final treatment option, in vitro fertilisation (IVF) can be considered. IVF does increase the risk of ovarian hyperstimulation syndrome. Using a 'freeze all' strategy makes it easier to transfer a single embryo and provides time for the ovaries to recover from hyperstimulation. A less effective alternative, but with much lower risks of ovarian hyperstimulation syndrome, is in vitro maturation instead of full IVF. This option avoids high-dose gonadotropin therapy.
Sources: en.wikipedia.org
An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion more narrowly refers to when both phases, dispersed and continuous, are liquids. In an emulsion, one liquid (the dispersed phase) is dispersed in the other (the continuous phase). Examples of emulsions include vinaigrettes, homogenized milk, liquid biomolecular condensates, and some cutting fluids for metal working. Two liquids can form different types of emulsions. As an example, oil and water can form, first, an oil-in-water emulsion, in which the oil is the dispersed phase, and water is the continuous phase. Second, they can form a water-in-oil emulsion, in which water is the dispersed phase and oil is the continuous phase. Multiple emulsions are also possible, including a "water-in-oil-in-water" emulsion and an "oil-in-water-in-oil" emulsion. Emulsions, being liquids, do not exhibit a static internal structure. The droplets dispersed in the continuous phase (sometimes referred to as the "dispersion medium") are usually assumed to be statistically distributed to produce roughly spherical droplets. The term "emulsion" is also used to refer to the photo-sensitive side of photographic film. Such a photographic emulsion consists of silver halide colloidal particles dispersed in a gelatin matrix.
=== Wound occlusion === Many animals are able to block off the area around an injury rapidly, by coagulating their blood or body fluid. Invertebrates with hydrostatic skeletons (moving by peristalsis) are unable to move without internal fluid under pressure, while those with an open circulation (body fluid not confined to blood vessels) quickly die from loss of body fluid. In addition, open wounds allow bacteria to enter the body. The invertebrate coagulation system is comparable with the innate immune system (the simpler of two systems of protection against infection) of vertebrates.
Paxillosida (7 families, 48 genera, 372 species) This is a primitive order whose members do not extrude their stomach when feeding and both anus and tube feet suckers are absent. Papulae are present on their aboral surface, and they possess marginal plates and paxillae. They mostly inhabit soft substrates. There is no brachiolaria stage in their larval development. The comb starfish (Astropecten polyacanthus) is a member of this order. Spinulosida (1 family, 8 genera, 121 species) Most species in this order lack pedicellariae; all have a delicate skeletal arrangement with small or no marginal plates on the disc or arms. They have numerous groups of short spines on the aboral surface.
The need to recognize sugars is commonly encountered in nature and lectins have independently evolved many times, so that proteins that act as "lectins" come in many structurally distinct folds. The functionality of lectins have also evolved beyond simple recognition: "legume-type" lectins act as toxins to deter predation (with the most famous example being phytohaemagglutinin from legumes) while the separate ricin-type lectin serves to guide the catalytic A chain into victim cells.
== Society and culture == Depictions of heart attacks in popular media often include collapsing or loss of consciousness which are not common symptoms; these depictions contribute to widespread misunderstanding about the symptoms of myocardial infarctions, which in turn contributes to people not getting care when they should.
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.
No regulator in a major market has approved it for human use. It appears in research settings and in products marketed outside pharmacy channels. Legal status for personal possession varies by country.