The short version of melanocortin receptor fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-11-11. 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.
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.
Melanotan II is a synthetic peptide analog modeled on alpha-melanocyte-stimulating hormone, a naturally occurring signaling peptide involved in pigmentation. Its structure is a cyclic heptapeptide containing two non-natural substitutions, norleucine at position four and D-phenylalanine at position seven. These modifications resist enzymatic breakdown and extend the molecule's activity relative to the native hormone. The compound binds melanocortin receptors and is studied mainly as a pharmacological tool rather than a therapeutic product. It has never received approval as a medicine in any major jurisdiction.
| 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 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.
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.
Melanotan II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
No regulatory authority has approved melanotan-2 for human use, and several countries classify it as a prescription-only or controlled substance, which restricts lawful supply. Material sold online is generally labelled as a research chemical and is not required to meet pharmaceutical standards of identity or purity. Published human data consist mainly of small uncontrolled studies, case reports and adverse-event notifications, so the evidence base is descriptive rather than confirmatory. Whether repeated melanocyte stimulation alters long-term naevus behaviour remains an open question that no completed trial has resolved.
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.
Insulin aspart, which was approved in 2000 and is marketed under the name Novolog among others, has effects comparable to those of insulin lispro, but has a lesser risk of nocturnal hypoglycemia. It works by replacing a proline with an aspartic acid at the B28 position. Insulin glulisine has nearly identical properties to the other two short-acting analogues, but differs in the fact that the amino acid asparagine at position B3 is replaced by lysine and the lysine in position B29 is replaced by glutamic acid. It was approved in 2004 and is sold under the name Apidra. These short-acting insulin analogues play a crucial role in modern diabetes management, as their fast onset and shorter duration of action allow for more precise postprandial glucose control. By closely mimicking endogenous insulin secretion, these analogues enhance glycemic stability, reduce post-meal blood sugar spikes, and minimize the risk of hypoglycemic events. Their pharmacokinetic properties make them particularly beneficial for individuals requiring flexible meal timing and those using intensive insulin therapy.
==== War crimes ==== The report found that Russian and South Ossetian assertions of perpetration of genocide were "neither founded in law nor substantiated by factual evidence." The report found that during the conflict "all sides to the conflict - Georgian forces, Russian forces and South Ossetian forces - committed violations of International Humanitarian Law and Human Rights Law." The report also found facts of ethnic cleansing of Georgians, saying that "several elements suggest the conclusion that ethnic cleansing was indeed practised against ethnic Georgians in South Ossetia both during and after the August 2008 conflict." The commission noted that "The use of artillery and cluster munitions by Russian forces in populated areas also led to indiscriminate attacks and the violation of rules on precautions." The commission said that Russian military mostly did not halt South Ossetian acts of deliberate violence against civilians during the conflict and after the cease-fire.
The College of Pharmacy is one of the oldest in the United States, and the oldest west of the Allegheny Mountains. It offers PharmD, MS and PhD degrees, including some online programs. Its graduates have a 100% placement rate prior to graduation. It is ranked in the top 25% of pharmacy programs in the US.
Biochemistry, or biological chemistry (distinct from chemical biology), is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology, and metabolism. Over the last decades of the 20th century, biochemistry has become successful at explaining living processes through these three disciplines. Almost all areas of the life sciences are being uncovered and developed through biochemical methodology and research. Biochemistry focuses on understanding the chemical basis that allows biological molecules to give rise to the processes that occur within living cells and between cells, in turn relating greatly to the understanding of tissues and organs as well as organism structure and function. Biochemistry is closely related to molecular biology, the study of the molecular mechanisms of biological phenomena. Much of biochemistry deals with the structures, functions, and interactions of biological macromolecules such as proteins, nucleic acids, carbohydrates, and lipids. They provide the structure of cells and perform many of the functions associated with life. The chemistry of the cell also depends upon the reactions of small molecules and ions. These can be inorganic (for example, water and metal ions) or organic (for example, the amino acids, which are used to synthesize proteins). The mechanisms used by cells to harness energy from their environment via chemical reactions are known as metabolism.
Immediate-release oxycodone (OxyFast, OxyIR, OxyNorm, Roxicodone, Shortec) Controlled-release oxycodone (OxyContin, Xtampza ER, Oxypro) – 10–12 hour duration Oxycodone tamper-resistant (OxyContin OTR) Immediate-release oxycodone with paracetamol (acetaminophen) (Percocet, Endocet, Roxicet, Tylox) Immediate-release oxycodone with aspirin (Endodan, Oxycodan, Percodan, Roxiprin) Immediate-release oxycodone with ibuprofen (Combunox) Controlled-release oxycodone with naloxone (Targin, Targiniq, Targinact) – 10–12 hour duration Controlled-release oxycodone with naltrexone (Troxyca) – 10–12 hour duration
Sources: en.wikipedia.org
Extracellular Domain: The extracellular domain is composed of multiple immunoglobulin-like subdomains, including the variable (V) domain and two constant domains (C1 and C2). The V domain serves as the principal binding site for a wide range of ligands, such as advanced glycation end-products (AGEs), S100 proteins, and high mobility group box 1 (HMGB1). This ligand-binding feature is essential for triggering downstream signaling cascades that lead to inflammatory responses. Transmembrane Domain: The transmembrane domain helps anchor RAGE in the cellular membrane, ensuring that the receptor remains available to interact with extracellular ligands and transmit signals into the cell. Cytoplasmic Domain: The cytoplasmic domain, also referred to as the cytosolic domain, is integral for intracellular signal transduction. When ligands bind to the extracellular domain, this segment interacts with intracellular signaling proteins, initiating processes such as the activation of NF-κB, a key inflammatory pathway. It has been observed that the absence of the cytoplasmic domain impairs the receptor's ability to transmit signals effectively, which underlines its importance in RAGE-mediated signaling.
=== Sleep apnea === Sleep apnea is a condition characterized by repeated interruptions in breathing during sleep, significantly affecting the flow of blood through the brain's blood vessels. These interruptions cause intermittent hypoxia, leading to vascular changes such as the constriction of cerebral blood vessels, thereby impacting overall brain blood flow. Sleep apnea can also result in reduced blood flow in the ciliary artery area, contributing to the development of NAION through various mechanisms. The results of a retrospective study investigating high altitude (7,000-9,000 feet) as a potential risk factor for NAION suggested that high-altitude-associated NAION might be linked to undiagnosed obstructive sleep apnea. The study concluded that NAION could occur under high-altitude conditions, often in younger individuals with obstructive sleep apnea and "disc-at-risk". Each apnea episode typically causes temporary increases in blood pressure and heart rate, leading to fluctuations that can result in irregular blood flow to the brain. This may cause long-term changes in the structure and function of cerebral blood vessels. The brain's mechanism for maintaining constant blood flow despite changes in systemic blood pressure, known as cerebral autoregulation, can be impaired by sleep apnea. This impairment results in periods of both reduced and excessive cerebral blood flow. Repeated airway obstruction during sleep leads to intermittent hypoxia, causing oxidative stress and damaging endothelial cells of blood vessels, including those supplying the optic nerve head.
==== GnRH-associated peptide ==== GnRH-associated peptide (GAP), a 56-amino-acid peptide cleaved from the GnRH precursor, was shown in 1985 to inhibit prolactin secretion in rat pituitary cultures at a potency comparable to dopamine. Its physiological significance in vivo remains uncertain, as results have varied across species.
The word frankfurter comes from Frankfurt, Germany, where pork sausages similar to hot dogs originated. These sausages, Frankfurter Würstchen, were known since the 13th century and given to the people on the event of imperial coronations, starting with the coronation of Maximilian II, Holy Roman Emperor, as King. "Wiener" refers to Vienna, Austria (German: Wien), home to a sausage made of a mixture of pork and beef. Johann Georg Lahner, an 18th/19th century butcher from the Franconian city of Coburg, is said to have brought the Frankfurter Würstchen to Vienna, where he added beef to the mixture and simply called it Frankfurter. Nowadays, in German-speaking countries, except Austria, hot dog sausages are called Wiener or Wiener Würstchen (Würstchen means "little sausage"), to differentiate them from the original pork-only mixture from Frankfurt. In Swiss German, it is called Wienerli, while in Austria the terms Frankfurter or Frankfurter Würstel are used.
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 cyclic peptide designed as an analog of alpha-melanocyte-stimulating hormone. It acts on melanocortin receptors and is best known from research into pigmentation. It is not an approved pharmaceutical product.