This is a working overview of melanocortin receptor, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-03-25 and is reviewed periodically as new material appears.
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.
The peer-reviewed record is dominated by small early-phase studies, case reports and pharmacovigilance summaries rather than large randomised trials. Papers typically examine tanning response, receptor selectivity or patterns of reported adverse events. Many note that participants obtained the peptide outside a clinical setting, which limits verification of composition and administered amount. Reported events vary widely, and causality is frequently unclear because the identity and purity of self-sourced material are unknown. Open questions include whether repeated melanocortin receptor stimulation produces cumulative effects, and how often label claims match actual content.
Identification in laboratories relies on reversed-phase liquid chromatography coupled with tandem mass spectrometry, with product-ion spectra compared against a certified reference standard. High-resolution mass spectrometry supplies accurate mass confirmation, and peptide mapping after enzymatic digestion separates melanotan II from closely related analogues. Quantitation of seized material is complicated by unknown counter-ions and residual trifluoroacetate left from purification. Immunoassays raised against alpha-melanocyte-stimulating hormone can cross-react, so chromatographic confirmation is normally required. Urinary detection windows are short, and reported limits of detection differ substantially between laboratories.
| 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 |
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.
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.
Slavery existed in ancient China as early as the Shang dynasty. Slavery was employed largely by governments as a means of maintaining a public labour force. After the Southern and Northern Dynasties, due to years of poor harvests, the influx of foreign tribes, and the resulting wars, the number of slaves exploded. They became a class and were called "jianmin (Chinese: 贱民)" (literally "inferior person"). As stated in The commentary of Tang Code: "Slaves and inferior people are legally equivalent to livestock products". They always had a low social status, and even if they were deliberately murdered, the perpetrators received only a year in prison, and were punished even when they reported the crimes of their lords. However, in the later period of the dynasty, perhaps because the increase in the number of slaves slowed down again, the penalties for crimes against them became harsh again. For example, the famous contemporary female poet Yu Xuanji was publicly executed for murdering her own slave. Many Han Chinese were enslaved in the process of the Mongol invasion of China proper. According to Japanese historians Sugiyama Masaaki (杉山正明) and Funada Yoshiyuki (舩田善之), Mongolian slaves were owned by Han Chinese during the Yuan dynasty. Slavery has taken various forms throughout China's history. It was reportedly abolished as a legally recognized institution, including in a 1909 law fully enacted in 1910, although the practice continued until at least 1949.
Nalin Chandra Wickramasinghe (born 20 January 1939) is a Sri Lankan-born British mathematician and astronomer. His research interests include the interstellar medium, infrared astronomy, light scattering theory, applications of solid-state physics to astronomy, the early Solar System, comets, astrochemistry, the origin of life and astrobiology. A student and collaborator of Fred Hoyle, the pair worked jointly for over 40 years as the most famous proponents of a non-mainstream version of panspermia, the proposal that life was seeded (or continues to be seeded) on Earth through space-based processes. In 1974 they proposed that some dust in interstellar space matched the spectral characteristics of freeze-dried bacteria, which was largely ignored at its publishing while the ubiquity of polycyclic aromatic hydrocarbons explains the apparent match. Wickramasinghe has advanced numerous fringe claims, including the argument that various outbreaks of illnesses on Earth are of extraterrestrial origins, including the 1918 flu pandemic and certain outbreaks of polio and mad cow disease. For the 1918 flu pandemic they proposed that cometary dust brought the virus to Earth simultaneously at multiple locations—a view dismissed by experts on this pandemic. Claims connecting terrestrial disease and extraterrestrial pathogens have been rejected by the scientific community. Wickramasinghe has written more than 40 books about astrophysics and related topics; he has made appearances on radio, television and film, and he writes online blogs and articles.
H2NCO−2 + 2 H2O ⇌ NH+4 + HCO−3 + OH− H2NCO−2 + H2O ⇌ NH+4 + CO2−3 Calcium carbamate is soluble in water, whereas calcium carbonate is not. Adding a calcium salt to an ammonium carbamate/carbonate solution will precipitate some calcium carbonate immediately, and then slowly precipitate more as the carbamate hydrolyzes.
=== Young Investigator (YI) Post-Doctoral Programme === (RCB-YI award) has been initiated to nurture outstanding recent PhDs with innovative ideas and the drive to pursue novel discoveries under the mentorship of RCB faculty. RCB-YI award has been instituted for both Indian and Foreign nationals on the competitive basis with initial appointment for three years which is extendable on rigorous review for additional two years.
Sources: en.wikipedia.org
Lieutenant Colonel James Edward Noel Bridgeman Shaw, Grenadier Guards, 559678; Brigade Major, Household Division, on the occasion of the Coronation of Their Majesties The King and The Queen. Nicholas Kester Smith, Director of Racing and Public Affairs, Ascot Racecourse. David William Courtenay Whelton, , Music Advisor, on the occasion of the Coronation of Their Majesties The King and The Queen. James Wyndham Williams, Music Advisor, on the occasion of the Coronation of Their Majesties The King and The Queen.
== Data recovery after the discontinuation of Peptidome == The NCBI Peptidome database was discontinued in 2011, yet a joint effort by the PRIDE and Peptidome teams resulted in the transfer of all Peptidome data to PRIDE.
Conversely, the catabolic effect was much less in an older male, and no such effect was observed in adult females consuming a diet with sufficient calories and protein. The catabolic effects of CPA were found to be greater than those of corticosteroids. Although higher doses of CPA are necessary for considerable systemic AR antagonistic activity, it is notable that even low doses of oral CPA appear to be able to significantly antagonize AR signaling in the liver in women. This may be related to the hepatic first-pass effect of oral administration, and is evidenced by the fact that whereas combined birth control pills containing CPA increase SHBG levels by 300 to 400%, combined birth control pills containing various other progestins, with either androgenic or antiandrogenic activity, increase SHBG levels by only 50 to 300%. This is relevant as estrogens stimulate hepatic SHBG production while androgens inhibit hepatic SHBG production, and vice versa for their antagonists. The antiandrogenic activity of CPA may also be responsible for the relatively greater risk of venous thromboembolism with CPA-containing birth control pills compared to those containing other progestins. In rats, a dosage of CPA of 25 mg/kg/day results in complete regression of prostate gland growth in gonadally intact males. The equivalent dosage in humans, on the basis of body surface (conversion factor from rat to human of 6), was estimated to be approximately 4 mg/kg/day, or around 300 mg/day CPA for a 75 kg (165 lb) man.
Durand sold the patent to Bryan Donkin, who spent two years perfecting the method. Canned food subsequently began to be issued to the Royal Navy. The reason for lack of spoilage was unknown at the time, since it would be until the 1860s before Louis Pasteur demonstrated the role of microbes in food spoilage and developed pasteurization. The Crimean War saw issues with supplying soldiers in battle. In the British Army, rations were regularly halved, and many soldiers developed scurvy, to the point that the hospital in Scutari received more soldiers for scurvy than battle wounds. During the American Civil War, the food and rations of the Union Army and the Confederate States Army were meant to be mostly the same—meat, cornmeal, vegetables, vinegar, molasses, and hardtack—but supply issues plagued the Confederates as the war continued, forcing them to live off the land. The standard Union Army ration was roughly three-quarters pound (340 g) of meat, one pound (450 g) of flour or cornmeal, vegetables, vinegar, and molasses. To ensure that food lasted longer, rations often came in the form of hardtack biscuits, salted meat, and dehydrated vegetables. During campaigns, particularly as Union troops entered the south, seasonal fruits and vegetables were pillaged from farms and orchards. Both the Union and Confederate armies relied on lakes and streams for their water.
==== Revisionism in the 21st century ==== Despite the overall focus away from the Orthodox vs. Revisionist debates there have been new revisionist works that have emerged in the 21st century. One such example is Norman Naimark's 2019 Stalin and the Fate of Europe: The Postwar Struggle for Sovereignty.. Another work arguing that Stalin in fact sought to avoid the Cold War is the 2006 Stalin's Wars: From World War to Cold War, 1939-1953 by Geoffrey Roberts.
Sources: en.wikipedia.org
Roles for the ER chaperones GRP94, EDEM and BiP have been proposed prior to the 'dislocation' of RTA from the ER lumen to the cytosol in a manner that uses components of the endoplasmic reticulum-associated protein degradation (ERAD) pathway. ERAD normally removes misfolded ER proteins to the cytosol for their destruction by cytosolic proteasomes. Dislocation of RTA requires ER membrane-integral E3 ubiquitin ligase complexes, but RTA avoids the ubiquitination that usually occurs with ERAD substrates because of its low content of lysine residues, which are the usual attachment sites for ubiquitin. Thus, RTA avoids the usual fate of dislocated proteins (destruction that is mediated by targeting ubiquitinylated proteins to the cytosolic proteasomes). In the mammalian cell cytosol, RTA then undergoes triage by the cytosolic molecular chaperones Hsc70 and Hsp90 and their co-chaperones, as well as by one subunit (RPT5) of the proteasome itself, that results in its folding to a catalytic conformation, which de-purinates ribosomes, thus halting protein synthesis.
== Formulation == The formulation of a coating depends primarily on the function required of the coating and also on aesthetics required such as color and gloss. The four primary ingredients are the resin (or binder), solvent which may be water (or solventless), pigment(s) and additives (defoamers, surfactants, optical brighteners, etc.). Research is ongoing to remove heavy metals from coating formulations completely. For example, on the basis of experimental and epidemiological evidence, it has been classified by the IARC (International Agency for Research on Cancer) as a human carcinogen by inhalation (class I) (ISPESL, 2008).
=== Reductive routes === A nickel catalyst can hydrogenate unsaturated N-containing functional groups to amines. Suitable groups include nitriles, imines (including oximes), amides, azides, and nitro groups. Many amines are produced from aldehydes and ketones via reductive amination, reduction of an imine formed in situ or a two-step process. LiAlH4 is more commonly employed to reduce these groups at laboratory scale. In the case of nitriles, reactions are sensitive to acidic or alkaline conditions, which can hydrolyze the −CN group. Aniline (C6H5NH2) and derivatives are prepared by reduction of the corresponding nitroaromatics. In industry, hydrogen is the preferred reductant, whereas tin and iron are often employed in the laboratory.
== Method translation == Faster GC methods have shorter times but Kovats indices of the compounds may be conserved if proper method translation is applied. Temperatures of the temperature program stay the same, but ramps and times change when using a smaller column or faster carrier gas. If column dimensions Length×diameter×film are divided by 2 and gas velocity is doubled by using H2 in place of Helium, the hold times must be divided by 4 and the ramps must be multiplied by 4 to keep the same index and the same retention temperature for the same compound analyzed. Method translation rules are incorporated in some chromatography data systems.
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.
Regulatory treatment varies by country. In the United States, the European Union and Australia it is an unapproved drug and its sale is restricted, while some other jurisdictions list it as prescription-only or controlled. The applicable rules depend on the country of import.