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 2025-11-06. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Scientific discussion of Melanotan-2 spans pharmacology, dermatology, and public-health literature. Laboratory studies examine its receptor binding and cellular effects, while clinical reports describe outcomes observed after unregulated use. These two bodies of work differ in rigour and intent. Peer-reviewed trials of the compound as a medicine are limited, so much of the available information comes from case reports and surveillance data. Authors frequently note the gap between experimental findings and real-world use.
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.
| Property | Value | Notes |
|---|---|---|
| Compound class | Synthetic cyclic heptapeptide | Alpha-MSH analogue containing a D-phenylalanine residue |
| Molecular formula | C50H69N15O9 | Average molecular mass approximately 1024.2 g/mol |
| Appearance | White to off-white lyophilised powder | Normally supplied as a freeze-dried solid in a sealed vial |
| Solubility | Freely soluble in water and polar solvents | Dissolves readily in aqueous buffers and in alcohol-water mixtures |
| Receptor targets | MC1R, MC3R, MC4R, MC5R | Acts as a non-selective melanocortin receptor agonist |
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.
Analytical confirmation of identity relies on mass spectrometry, most often coupled to liquid chromatography. Reversed-phase high-performance liquid chromatography separates the peptide from related impurities and provides a purity estimate based on peak area. Electrospray ionization mass spectrometry then confirms the expected molecular mass, while tandem mass spectrometry can map the fragment sequence. For research-grade material, these two techniques together form the standard minimum. Purity figures reported by vendors are frequently not traceable to an independent laboratory.
Independent verification is central to quality control because the compound is not produced under pharmaceutical manufacturing standards. Third-party laboratories can measure purity, identity, residual solvents, and microbial contamination, though the scope of testing varies between services. Reported analyses of vendor samples have shown batch-to-batch variation in peptide content and the presence of truncated or oxidized species. How much of this variation reflects synthesis conditions versus storage and shipping is not well characterized. No harmonized reference standard exists for the material as sold.
Abnormal basal metabolic rate refers to a high or low basal metabolic rate (BMR). It has numerous causes, both physiological (part of the body's normal function) and pathological (associated with disease). An abnormal basal metabolic rate is not necessarily indicative of disease; a number of physiological factors can alter the BMR by influencing cellular metabolic activity. For instance, males are more likely than females to have a high BMR, and in women, the BMR may rise to abnormal levels during pregnancy or lactation. An individual's BMR varies greatly with age: infants and children typically have a high BMR, required for growth, while the elderly have a low BMR. Tall, thin people have a higher BMR than their shorter counterparts, even with the same weight, due to the greater surface area of their skin. The metabolic rate also decreases during sleep and increases in exercise, and individuals who exercise regularly have a higher BMR than those who are sedentary. Environmental temperature also has an effect: the BMR is increased in both heat and cold.
Aminosalicylic acid was introduced to clinical use in 1944. It was the second antibiotic found to be effective in the treatment of tuberculosis, after streptomycin. PAS formed part of the standard treatment for tuberculosis prior to the introduction of rifampicin and pyrazinamide. Its potency is less than that of the current five first-line drugs (isoniazid, rifampicin, ethambutol, pyrazinamide, and streptomycin) for treating tuberculosis and its cost is higher, but it is still useful in the treatment of multidrug-resistant tuberculosis. PAS is always used in combination with other anti-TB drugs. 4-Aminosalicylic acid has also been used in the treatment of inflammatory bowel disease (ulcerative colitis and Crohn's disease), but has been superseded by other drugs such as sulfasalazine and mesalazine. 4-Aminosalicylic acid has been investigated for the use in manganese chelation therapy, and a 17-year follow-up study shows that it might be superior to other chelation protocols such as EDTA.
Lutetium is a chemical element; it has symbol Lu and atomic number 71. It is a silvery white metal which resists corrosion in dry air, but not in moist air. Lutetium is the last element in the lanthanide series, and it is traditionally counted among the rare earth elements; it can also be classified as the first element of the sixth-period transition metals. Lutetium was independently discovered in 1907 by French scientist Georges Urbain, Austrian mineralogist Baron Carl Auer von Welsbach, and American chemist Charles James. All of these researchers found lutetium as an impurity in ytterbium. The dispute on the priority of the discovery occurred shortly after, with Urbain and Welsbach accusing each other of publishing results influenced by the published research of the other; the naming honor went to Urbain, as he had published his results earlier. He chose the name lutecium for the new element honoring the Latin name for Paris, Lutetia. In 1949 the spelling was changed to lutetium. In 1909, the priority was finally granted to Urbain and his names were adopted as official ones; however, the name cassiopeium (or later cassiopium) for element 71 proposed by Welsbach was used by many German scientists until the 1950s. Lutetium is not a particularly abundant element, although it is significantly more common than silver in the Earth's crust. It has few specific uses. Lutetium-176 is a relatively abundant (2.6%) radioisotope with a half-life of about 38 billion years, used to determine the age of minerals and meteorites.
30 October – A study finds that the world's remaining carbon budget for 1.5 °C of global warming is only half that of previous estimates, at less than 250 gigatonnes of carbon dioxide, or around six years of annual worldwide emissions. 31 October The first discovery of a virus, phage MiniFlayer, that attaches to another helper virus is reported. The coalition of research organizations and science funders behind Plan S publishes a proposal for moving scholarly communication towards open science practices that are more transparent, accessible, efficient and without author fees. Hazard research is published: a study further confirms noncompensable moist heat extremes will be beyond bounds of past human evolutionary environments for billions of people (9 Oct), an analysis calls for health policy regarding unhealthy ultra-processed foods (9 Oct), an analysis calls for action regarding the summarized environmental footprint of bitcoin mining (9 Oct), a global assessment of risk from increasing pollinator loss to crop pollination shows cocoa and coffee at high risk (12 Oct), a training data poisoning technique, 'Nightshade', against generative AI software specific to select prompts is described (20 Oct), a study indicates low deep sleep percentage is a modifiable dementia risk factor (30 Oct).
Sources: en.wikipedia.org
=== Treatment === In vitro studies have found that several agents are effective against E. floccosum. Disease-specific topical treatments for E. floccosum-related infections are usually effective, commonly with the use of terbinafine, itraconazole, and ketoconazole.
RCH(NHP)CO2H + R'CH(NH2)CO2CH3 → RCH(NHP)C(O)NH(CHR')CO2CH3 + H2O Subsequent to this coupling reaction, the amine protecting group P and the ester are converted to the free amine and carboxylic acid, respectively. For many amino acids, the ancillary functional groups are protected. The condensation of the amine and the carboxylic acid to form the peptide bond generally employs coupling agents to activate the carboxylic acid. The Bergmann azlactone peptide synthesis is a classic organic synthesis for the preparation of dipeptides.
==== Segmental fasciectomy with/without cellulose ==== Segmental fasciectomy involves excising part(s) of the contracted cord so that it disappears or no longer contracts the finger. It is less invasive than the limited fasciectomy, because not all the diseased tissue is excised and the skin incisions are smaller. The person is placed under regional anesthesia and a surgical tourniquet is used. The skin is opened with small curved incisions over the diseased tissue. If necessary, incisions are made in the fingers. Pieces of cord and fascia of approximately one centimeter are excised. The cords are placed under maximum tension while they are cut. A scalpel is used to separate the tissues. The surgeon keeps removing small parts until the finger can fully extend. The patient is encouraged to start moving their hand the day after surgery. After surgery people wear a light pressure dressing for four days, followed by an extension splint, typically continuously for a few weeks, then every night for eight weeks. The same procedure is used in the segmental fasciectomy with cellulose implant. After the excision and a careful hemostasis, the cellulose implant is placed in a single layer in between the remaining parts of the cord.
=== Shell collecting === The intricate color patterns of cone snails have made them one of the most popular species for shell collectors. Conus gloriamaris, also known as "Glory of the Seas", one of the most famous and sought-after seashells in past centuries, with only a few specimens in private collections. The rarity of this species' shells led to high market prices for the objects, until the habitat of this cone snail was discovered, which decreased prices dramatically.
Pat Wing I (パトウィング1, Pato Wingu Wan): Deka Red's personal fighter jet–themed Pat Wing that forms the head, torso, and upper legs of Deka Wing Robo. It also possesses the highest speed and mobility. Pat Wing II (パトウィング2, Pato Wingu Tsū): Deka Blue's personal VTOL-themed Pat Wing that forms the arms of Deka Wing Robo. It also possesses hovering capabilities, high stability, and wingtip blasters. Pat Wing III (パトウィング3, Pato Wingu Surī): Deka Green's personal cargo jet–themed Pat Wing that forms the lower legs of Deka Wing Robo. It is also highly confidential, making it suitable for the conveyance of dangerous goods. Pat Wing IV (パトウィング4, Pato Wingu Fō): Deka Yellow's personal stealth bomber–themed Pat Wing that forms the right foot of Deka Wing Robo. It also possesses high stealth and endurance capabilities, and is equipped with special arms such as flares and tear gas bombs. Pat Wing V (パトウィング5, Pato Wingu Faibu): Deka Pink's personal water bomber–themed Pat Wing that forms the left foot of Deka Wing Robo. It is also equipped with a speaker and fire-extinguishing capabilities.
Sources: en.wikipedia.org
No. It is a laboratory-made peptide, while the natural hormone is alpha-melanocyte-stimulating hormone, a longer peptide produced by the pituitary gland and by skin cells. Melanotan-2 mimics only a short active region of that hormone and contains non-natural residues such as D-phenylalanine.
No approved regulatory indication exists in major markets. An approval exists for a different peptide, afamelanotide, which is used for a rare photosensitivity disorder called erythropoietic protoporphyria. Melanotan-2 itself remains a research compound with no cleared clinical role.
Melanocortin-1 receptors on melanocytes are the receptor most closely linked to pigment production. The peptide is not selective, however, and also activates melanocortin-3, melanocortin-4, and melanocortin-5 receptors. That lack of selectivity is the usual explanation offered for both its range of observed effects and its off-target effects.
Major regulatory agencies have not approved it for any indication. Some countries permit it only under prescription frameworks, while others classify it as a controlled substance.