This is a working overview of MC1R, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
Melanotan-2 is a synthetic linear peptide built from seven amino acids arranged in a short chain. Its sequence is commonly written as Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH2, which includes a modified N-terminus and an amidated C-terminus. The molecule belongs to the melanocortin family and acts as a receptor agonist. Structural features such as the D-phenylalanine residue and the Nle substitution are associated with increased stability against enzymatic degradation relative to the natural parent peptide.
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.
The peptide was developed during the 1980s by researchers investigating melanocortin signalling and skin pigmentation pathways. Early work focused on analogues of alpha-melanocyte-stimulating hormone that would resist enzymatic breakdown more effectively than the parent molecule. Melanotan-2 emerged from that programme as a shortened, cyclised variant. Reports describing its synthesis and receptor activity later appeared in the scientific literature. Commercial availability grew through unregulated channels rather than through pharmaceutical approval.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms differ |
| Molecular weight | Approximately 1024 g/mol | Calculated for the free base |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water and polar solvents | Poorly soluble in non-polar solvents |
| Typical storage | -20 degrees Celsius, dry, protected from light | Refers to the solid form |
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.
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.
The peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
Melanotan-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
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.
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.
Human data remain limited and mostly short-term. Reports describe small trials and observational accounts rather than large controlled studies, so questions about dose-response relationships and long-term effects on melanocytes stay open. Whether repeated exposure alters naevus behaviour is not settled in the published record. Researchers also note that self-administered use outside clinical settings makes actual exposure difficult to quantify. Statements about efficacy and safety should therefore be read as preliminary rather than established.
Around 8,000 Canadians arrived in South Africa to fight for Britain. These arrived in contingents: the first on 30 October 1899, the second on 21 January 1900. A third contingent of cavalry (Strathcona's Horse) embarked on 16/17 March 1900. They remained until May 1902. With approximately 7,368 soldiers in a combat zone, the conflict became the largest engagement involving Canadian soldiers from the time of Confederation until the Great War. 270 of them died during the war. The arrival and movement of troops was widely documented by war photographers. English-born, and later Canadian, Inglis Sheldon-Williams was one of the most notable, documenting movement of hundreds of troops to Africa. The Canadian public was initially divided on the decision to go to war, as some did not want Canada to become Britain's 'tool' for engaging in armed conflicts. Many Anglophone citizens were pro-Empire, and wanted prime minister Sir Wilfrid Laurier to support the British. Many Francophone citizens felt threatened by the continuation of British imperialism to their national sovereignty. In the end, to appease citizens who wanted war and avoid angering those against it, Laurier sent 1,000 volunteers under the command of Lieutenant Colonel William Otter to aid the confederation in its war to 'liberate' the peoples of the Boer controlled states in South Africa. The volunteers were provided to the British if the latter paid costs of the battalion after it arrived in South Africa.
The Umayyad Caliphate ruled al-Andalus as a province until its independence in 756 under the Emirate of Córdoba, which in 929 gave way to a caliphate that lasted until it fragmented into states known as taifas, collapsing in 1031, and most of what is now central and southern Portugal falling under the Taifa of Badajoz. The taifas were conquered by Muslim forces from North Africa, first completely by the Almoravids by 1115, who were in turn followed by the Almohads in the 1140s. Northern incursions also occurred during this period, with Viking raids recorded from 844 into the 11th century.
Alpha-thalassemia is almost always inherited. It is a recessive trait - a single defective gene is insufficient to cause illness. Due to the involvement of four alpha globin genes, the inheritance pattern is complex, with varying severity depending on the number of gene mutations inherited from each parent. Normal individuals carry 4 alpha-globin genes, comprising autosomal pairs of the HBA1 and HBA2 genes. There are approximately 130 known mutations which can cause alpha thalassemia, mainly comprising deletion of part or all of a gene which then fails to produce alpha globin. If either one gene or two out of the four is faulty, the remaining genes produce sufficient alpha globin for normal life. If three genes are faulty, the sole functioning gene produces relatively small quantities of alpha globin, causing anemia and HbH disease. Four faulty genes (and therefore zero alpha globin) is incompatible with life. In rare cases alpha thalassemia can be acquired as a consequence of myelodysplastic cancer.
ectopic Occurring or developing in an abnormal place or position or in an unusual form or manner; displaced, malpositioned, or produced in an unnatural context. For example, ectopic expression refers to the expression of a particular gene product in a cell or tissue where it is not normally expressed. Contrast entopic.
Sources: en.wikipedia.org
== External links == Anatomy Atlases – Microscopic Anatomy, plate 07.141 - "Axillary Sweat Gland: Myoepithelium" Histology image: 43_13 at the University of Oklahoma Health Sciences Center - "thick skin" Histology at KUMC glands-glands09 "Simple Tubular Coiled" Costoff, A., Essentials of Human Physiology, archived from the original on 2015-11-20{{citation}}: CS1 maint: bot: original URL status unknown (link)
==== Freezing food ==== To preserve food over long periods, the temperature should be maintained below 0 °F (−18 °C). Careful thawing and immediate cooking are necessary to maintain food safety. Food frozen at −18 °C (0 °F) or below may be preserved almost indefinitely, although its quality is likely to deteriorate over time. The United States Department of Agriculture, Food Safety and Inspection Service, publishes a chart showing the suggested freezer storage time for common foods.
== See also == Beaten coffee – Indian coffee beverage Caffè crema – Coffee drink Coffee portal Dalgona coffee – Whipped coffee drink Frappe (New England) – Cold dairy beveragePages displaying short descriptions of redirect targets Frappuccino – Starbucks iced coffee drink
In turn, these conditions of hypoxia and hypercapnia will trigger additional effects on the body such as Cheyne–Stokes respiration. Some people with sleep apnea are unaware that they have the condition. In many cases, it is first observed by a family member. An in-lab sleep study overnight is the preferred method for diagnosing sleep apnea. In the case of OSA, the outcome that determines disease severity and guides the treatment plan is the apnea-hypopnea index (AHI). This measurement is calculated from totaling all pauses in breathing and periods of shallow breathing lasting greater than 10 seconds and dividing the sum by total hours of recorded sleep. In contrast, for CSA the degree of respiratory effort, measured by esophageal pressure or displacement of the thoracic or abdominal cavity, is an important distinguishing factor between OSA and CSA. A systemic disorder, sleep apnea is associated with a wide array of effects, including increased risk of car crashes, hypertension, cardiovascular disease, myocardial infarction, stroke, atrial fibrillation, insulin resistance, kidney disease, memory loss, neurodegeneration, low testosterone, and higher incidence of cancer. Further research is being conducted on the potential of using biomarkers to understand which chronic diseases are associated with sleep apnea on an individual basis. Treatment may include lifestyle changes, mouthpieces, breathing devices, and surgery. Effective lifestyle changes may include avoiding alcohol, losing weight, quitting smoking, and sleeping on one's side.
Inflammatory conditions of the lung tissue are pneumonia, of the respiratory tract are bronchitis and bronchiolitis, and of the pleurae surrounding the lungs pleurisy. Inflammation is usually caused by infections due to bacteria or viruses. When the lung tissue is inflamed due to other causes it is called pneumonitis. One major cause of bacterial pneumonia is tuberculosis. Chronic infections often occur in those with immunodeficiency and can include a fungal infection by Aspergillus fumigatus that can lead to an aspergilloma forming in the lung. In the US certain species of rat can transmit a hantavirus to humans that can cause untreatable hantavirus pulmonary syndrome with a similar presentation to that of acute respiratory distress syndrome (ARDS). Alcohol affects the lungs and can cause inflammatory alcoholic lung disease. Acute exposure to alcohol stimulates the beating of cilia in the respiratory epithelium. However, chronic exposure has the effect of desensitising the ciliary response which reduces mucociliary clearance (MCC). MCC is an innate defense system protecting against pollutants and pathogens, and when this is disrupted the numbers of alveolar macrophages are decreased. A subsequent inflammatory response is the release of cytokines. Another consequence is the susceptibility to infection.
Sources: en.wikipedia.org
No. Melanotan-2 is manufactured synthetically. The naturally occurring peptide in the same family is alpha-melanocyte-stimulating hormone, which the body produces as part of normal endocrine and neural signalling.
Both are synthetic analogues derived from the same parent hormone. Reference descriptions usually characterise afamelanotide as more selective for the MC1R subtype, whereas melanotan-2 is reported to interact with a wider range of melanocortin receptors.
Early studies explored melanocortin signalling and pigmentation, which later led to informal use of the label tanning peptide. That label is not a regulatory category and does not imply approved status for any purpose.
It is a synthetic cyclic heptapeptide and an analogue of alpha-melanocyte-stimulating hormone. The molecule is produced by chemical synthesis rather than extracted from a biological source.