This is a working overview of MC1R, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-04-09. Anything still debated is marked as such rather than presented as settled.
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.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, the naturally occurring peptide involved in pigmentation signalling. Its sequence is conventionally written as Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, with a lactam bridge joining the aspartate side chain to the lysine side chain. The empirical formula is C50H69N15O9 and the monoisotopic mass lies near 1023.5 daltons. N-terminal acetylation and the D-configured phenylalanine both increase resistance to enzymatic breakdown compared with the parent hormone.
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.
| 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 |
The compound was developed in the late 1980s and 1990s by academic researchers investigating photoprotection. The rationale held that stimulating melanin production might reduce ultraviolet damage to skin and lower skin cancer risk. Early work examined receptor binding, pigment response, and short-term tolerability in small studies. That program did not produce an approved drug, and formal development stalled after early-phase trials. Whether induced pigmentation confers meaningful photoprotection remains an open question.
Outside regulated medicine, melanotan II circulates through online vendors as a research chemical, often marketed for tanning. Products sold this way vary widely in purity, concentration, and labeling accuracy, and independent testing has documented discrepancies. Published reports describe both pigment effects and adverse reactions, including nausea, flushing, and darkening of existing moles. Long-term safety data are sparse, and no large controlled trial has established a risk profile. Questions about cumulative effects on melanocytes remain unresolved in the literature.
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.
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.
Melanotan II is a synthetic cyclic heptapeptide that acts as an agonist at melanocortin receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide involved in pigment production. The analogue carries a lactam bridge that constrains the ring and slows enzymatic breakdown relative to the native hormone. In research literature it appears under several abbreviations, and naming conventions are not fully standardized. Published descriptions usually place it within the broader melanocortin agonist family.
Receptor binding at MC1R on melanocytes raises intracellular cyclic AMP and increases expression of tyrosinase and related enzymes. The downstream result is greater synthesis of eumelanin, the dark pigment, without ultraviolet exposure acting as the trigger. The compound is not selective, however, and also engages MC3R, MC4R and MC5R, which are expressed in the central nervous system and elsewhere. That lack of selectivity is the explanation usually offered for effects reported outside pigmentation, including appetite suppression and nausea. Selectivity remains a central theme in comparative studies of related peptides.
In 1976, economist Rudolf Meidner established a study committee that came up with a proposal called the Meidner Plan which entailed the transferring of the excess profits into investment funds controlled by the workers in said efficient firms, with the goal that firms would create further employment and pay workers higher wages in return rather than unduly increasing the wealth of company owners and managers. Capitalists immediately denounced the proposal as socialism and launched an unprecedented opposition and smear campaign against it, threatening to terminate the class compromise established in the 1938 Saltsjöbaden Agreement.
== Systemic effects == An infectious organism can escape the confines of the immediate tissue via the circulatory system or lymphatic system, where it may spread to other parts of the body. If an organism is not contained by the actions of acute inflammation, it may gain access to the lymphatic system via nearby lymph vessels. An infection of the lymph vessels is known as lymphangitis, and infection of a lymph node is known as lymphadenitis. When lymph nodes cannot destroy all pathogens, the infection spreads further. A pathogen can gain access to the bloodstream through lymphatic drainage into the circulatory system. When inflammation overwhelms the host, systemic inflammatory response syndrome is diagnosed. When it is due to infection, the term sepsis is applied, with the terms bacteremia being applied specifically for bacterial sepsis and viremia specifically to viral sepsis. Vasodilation and organ dysfunction are serious problems associated with widespread infection that may lead to septic shock and death.
== Lead-like == During drug discovery, lipophilicity and molecular weight are often increased in order to improve the affinity and selectivity of the drug candidate. As a result, it is often difficult to maintain drug-likeness (i.e., RO5 compliance) during hit and lead optimization. To solve this problem, it has been proposed that members of screening libraries from which hits are discovered should be biased toward lower molecular weight and lipophilicity so that medicinal chemists will have an easier time in delivering optimized drug development candidates that are also drug-like. Hence the rule of five has been extended to the rule of three (RO3) for defining lead-like compounds. A rule of three compliant compound is defined as one that has:
== Structure == GFP has a beta barrel structure consisting of eleven β-strands with a pleated sheet arrangement, with an alpha helix containing the covalently bonded chromophore 4-(p-hydroxybenzylidene)imidazolidin-5-one (HBI) running through the center. Five shorter alpha helices form caps on the ends of the structure. The beta barrel structure is a nearly perfect cylinder, 42Å long and 24Å in diameter (some studies have reported a diameter of 30Å), creating what is referred to as a "β-can" formation, which is unique to the GFP-like family. HBI, the spontaneously modified form of the tripeptide Ser65–Tyr66–Gly67, is nonfluorescent in the absence of the properly folded GFP scaffold and exists mainly in the un-ionized phenol form in wtGFP. Inward-facing sidechains of the barrel induce specific cyclization reactions in Ser65–Tyr66–Gly67 that induce ionization of HBI to the phenolate form and chromophore formation. This process of post-translational modification is referred to as maturation. The hydrogen-bonding network and electron-stacking interactions with these sidechains influence the color, intensity and photostability of GFP and its numerous derivatives. The tightly packed nature of the barrel excludes solvent molecules, protecting the chromophore fluorescence from quenching by water. In addition to the auto-cyclization of the Ser65-Tyr66-Gly67, a 1,2-dehydrogenation reaction occurs at the Tyr66 residue. Besides the three residues that form the chromophore, residues such as Gln94, Arg96, His148, Thr203, and Glu222 all act as stabilizers.
Blood plasma fractionation are the general processes separating the various components of blood plasma, which in turn is a component of blood obtained through blood fractionation. Plasma-derived immunoglobulins are giving a new narrative to healthcare across a wide range of autoimmune inflammatory diseases.
Sources: en.wikipedia.org
== Uses of bases == Sodium hydroxide is used in the manufacture of soap, paper, and the synthetic fiber rayon. Calcium hydroxide (slaked lime) is used in the manufacture of bleaching powder. Calcium hydroxide is also used to clean the sulfur dioxide, which is caused by the exhaust, that is found in power plants and factories. Magnesium hydroxide is used as an 'antacid' to neutralize excess acid in the stomach and cure indigestion. Sodium carbonate is used as washing soda and for softening hard water. Sodium bicarbonate (or sodium hydrogen carbonate) is used as baking soda in cooking food, for making baking powders, as an antacid to cure indigestion and in soda acid fire extinguisher. Ammonium hydroxide is used to remove grease stains from clothes
Following this report, American neurologist Silas Weir Mitchell tried peyote and published his experience with it in December 1896. After reading Mitchell's article, others, including psychologist and sexologist Havelock Ellis and American psychologist William James tried peyote and described their experiences. The German chemist Arthur Heffter isolated and ingested mescaline from peyote, experiencing psychedelic effects with the pure compound, in 1897, and published his findings in 1898. Austrian chemist Ernst Späth synthesized mescaline for the first time in 1919. The German pharmaceutical company Merck then began distributing pharmaceutical mescaline in 1920. The German psychiatrist Kurt Beringer, a student of Lewin and an acquaintance of Hermann Hesse and Carl Jung, became the father of psychedelic psychiatry and conducted experiments with mescaline in more than 60 people starting in 1921. He published his monograph on the subject, Der Meskalinrausch (Mescaline Intoxication), in 1927. German–American psychologist Heinrich Klüver published his monograph, Mescal: The Divine Plant and Its Psychological Effects, in English in 1928. He is said to have been the first to attempt to provide a phenomenological description of the psychedelic experience. The French pharmacist Alexandre Rouhier also studied and published on peyote and mescaline with his book Le Peyotl: La Plante Qui Fait les Yeux Émerveillés (Peyote: The Plant That Fills the Eyes with Marvels) in 1927.
Some endocrinologists and clinicians include the paracrine system as part of the endocrine system, but there is not consensus. Paracrines are slower acting, targeting cells in the same tissue or organ. An example of this is somatostatin which is released by some pancreatic cells and targets other pancreatic cells.
Drawing on existing heroin and cannabis smuggling networks, the Guadalajara Cartel, led by Miguel Ángel Félix Gallardo, emerged as intermediaries, transporting Colombian cocaine across the Mexico–United States border. By the mid-1980s, the Guadalajara Cartel had firmly established itself as a reliable transporter, initially paid in cash but shifting by the late 1980s to a payment-in-kind arrangement. While many factors contributed to the escalation of drug trafficking violence, security analysts trace the origins of cartel power to the unraveling of an implicit arrangement between traffickers and then-ruling Institutional Revolutionary Party (PRI), which began to lose its grip on power in the 1980s. The fighting between rival drug cartels began in earnest after the 1989 arrest of Félix Gallardo, with cartel infighting escalating in the 1990s.
Sources: en.wikipedia.org
==== Resale exemptions and sales tax (United States) ==== Often, in the United States, wholesalers are not required to charge their buyers sales tax, if the buyer has a resale license in the state the wholesaler is located. Out-of-state buyers are not charged sale tax by wholesalers. Documentation requirements vary by state.
He received his first Golden Globe Award for Best Actor – Motion Picture Drama and nominations for an Academy Award, a BAFTA Award and a Screen Actors Guild Award. In 2006, DiCaprio starred in the crime film The Departed and the political war thriller Blood Diamond. In Scorsese's The Departed, DiCaprio played the role of Billy Costigan, a state trooper working undercover in the Irish Mob in Boston, someone he characterizes as being in a "constant 24-hour panic attack". DiCaprio especially liked the experience of working with co-star Jack Nicholson, describing a scene with him as "one of the most memorable moments" of his life as an actor. In preparation, he visited Boston to interact with people associated with the Irish Mob and gained 15 pounds (6.8 kg) of muscle. Critically acclaimed, the film grossed $291 million against a budget of $90 million, becoming DiCaprio and Scorsese's highest-grossing collaboration to that point. Peter Travers of Rolling Stone praised DiCaprio's and co-star Matt Damon's performances as "explosive, emotionally complex", but felt that Nicholson overshadowed the two. Despite DiCaprio's leading role in The Departed, the film's distributor Warner Bros. Pictures submitted his performance for a Best Supporting Actor nomination at the AMPAS to avoid internal conflict with his part in Blood Diamond. Instead, his co-star Mark Wahlberg was nominated, though DiCaprio earned other accolades for The Departed, including a Satellite Award for Best Supporting Actor and Best Actor nominations at the Golden Globes and BAFTA Awards.
In December 2013, a Formal Dispute Resolution was filed, which contained the requirements of the FDA for further studies. These include two studies in healthy subjects to determine if flibanserin impairs their ability to drive, and to determine if it interferes with other biochemical pathways. The Agency agreed to call a new Advisory Committee meeting to consider whether the risk-benefit ratio of flibanserin was favorable after this additional data was obtained. In June 2015, the US FDA Advisory Committee, which includes the Bone, Reproductive, and Urologic Drugs Advisory Committee (BRUDAC) and the Drug Safety and Risk Management Advisory Committee (DSRM), recommended approval of the drug by 18–6, with the proviso that measures be taken to inform women of the drug's side effects. On 18 August 2015, the FDA approved Addyi (flibanserin) for the treatment of premenopausal women with low sexual desire that causes personal distress or relationship difficulties. The approval specified that flibanserin should not be used to treat low sexual desire caused by co-existing psychiatric or medical problems; low sexual desire caused by problems in the relationship; or low sexual desire due to medication side effects. As of August 2015, Sprout Pharmaceuticals had not yet made an application to the European Medicines Agency for a marketing authorization.
After initial releases on Dais Records, Hospital Productions, What's Your Rupture?, and Eisold's own Heartworm Press, he signed to Matador Records, who re-released his self-released debut album, Love Comes Close, on November 3, 2009.
== Other uses == Maxim, New Jersey, an unincorporated community in Monmouth County, New Jersey, United States Maxim (philosophy), a principle that an individual uses in making a decision Maxim (coffee), the first American brand of freeze-dried coffee, made by General Foods Maxim gun, the first self-acting machine gun Maxim Cup, South Korean Go competition Maxim DL, software package created by Cyanogen Imaging Maxim Wien, brothel in Vienna, Austria Legal maxim, certain guiding principles of law and jurisprudence Pragmatic maxim, maxim of logic formulated by Charles Sanders Peirce SilencerCo Maxim 50, a muzzle-loading rifle that includes an integrated sound suppressor
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.
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.