A practical reference on melanocortin receptor: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-04-27. Anything still debated is marked as such rather than presented as settled.
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.
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 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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Belongs to the melanocortin agonist family |
| Key substitutions | Nle4 and D-Phe7 | Improve resistance to enzymatic degradation |
| Molecular formula | C50H69N15O9 | Approximately 1024 g/mol |
| Regulatory status | Not approved as a medicine | Distributed as a research chemical |
| Common synonyms | Melanotan II, MT-II, MT-2 | Spelling varies across sources |
Melanotan-2 is a synthetic cyclic heptapeptide designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous tridecapeptide that regulates pigment production. Two modifications distinguish it from the natural hormone: norleucine replaces methionine at the N-terminus, which limits oxidation, and a D-phenylalanine substitution raises receptor affinity. The ring is closed through an aspartate-lysine lactam bridge, giving the molecule a constrained conformation. The free base has a molecular mass near 1024 daltons, and commercial material is usually supplied as an acetate salt. It appears in the literature as a research peptide rather than an approved therapeutic agent.
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.
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its structure substitutes a lactam bridge between side chains to increase stability relative to the native hormone. The compound is also known by the shorthand MT-II and by several non-proprietary synonyms used in research catalogues. It is not an approved therapeutic product in any major jurisdiction; material sold under this name is typically offered as a laboratory reagent rather than as a medicine.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
Moist desquamation is a description of the clinical pattern seen as a consequence of radiation exposure where the skin thins and then begins to weep because of loss of integrity of the epithelial barrier and decreased oncotic pressure. Moist desquamation is a rare complication for most forms of radiology; however, it is far more common in fluoroscopy where threshold doses lie between 10 and 15 Gy and increasingly common above 15 Gy. It has been noted that fractionation of fluoroscopic procedures significantly reduces the likelihood of moist desquamation occurring. In animal studies done on pig skin, moist desquamation was found to occur with a 50% of the time after a single dose of 28 Gy; however, a 2×18 Gy fractionation scheme (36 Gy total dose) was needed to produce the same 50% occurrence. Moist desquamation is a common side effect of radiotherapy treatment, where approximately 36% of radiotherapy patients will present with symptoms of moist desquamation. While modern megavoltage external beam radiotherapy have peak radiation doses below the skin, older orthvoltage systems have peak radiation doses at the skin of a patient. As such, moist desquamtation and other skin related radiotherapy complications were significantly more commonplace before the introduction of higher energy cobalt therapy and linear accelerator systems between the 1950s to 1970s. Historically, this was a common phenomenon in Hiroshima and Nagasaki during World War II with the atomic bomb attacks from the United States.
The American Food and Drug Administration recommends moderate consumption of fish (4 oz weekly for children and 8–12 oz weekly for adults) as part of a healthy and balanced diet. The British National Health Service gives similar advice, recommending at least two portions (about 10 oz) of fish weekly. The Chinese National Health Commission recommends slightly more, advising 10–20 oz of fish weekly.
In non-small cell lung cancer, both mRNA and protein levels of TMPRSS11D are elevated in tumor tissue compared with adjacent normal tissue, and high protein expression is an independent predictor of poorer overall survival. Plasminogen (PLG), from which originates the mini-plasmin that can cleave the F-protein, is highly expressed in liver cancers. Its expression is also increased in a wide range of other malignant neoplasms. Factor X (F10) is frequently expressed in normal liver and in liver cancers. SeV constructs were created with a modified protease cleavage site. The modification allowed the recombinant virus to specifically infect cancer cells that expressed the corresponding proteases, which can cleave a modified protease cleavage site.
Sources: en.wikipedia.org
Furthermore, the NP protein plays a crucial role in enhancing primary transcription. Without newly synthesized NP protein, early transcription occurs at minimal levels, while its presence restores normal transcriptional activity. These findings indicate that the synthesis of these proteins facilitates the transition from preliminary to efficient transcription, underscoring their importance in the viral life cycle.
Acute inflammation is characterized by marked vascular changes, including vasodilation, increased permeability and increased blood flow, which are induced by the actions of various inflammatory mediators. Vasodilation occurs first at the arteriole level, progressing to the capillary level, and brings about a net increase in the amount of blood present, causing the redness and heat of inflammation. Increased permeability of the vessels results in the movement of plasma into the tissues, with resultant stasis due to the increase in the concentration of the cells within blood – a condition characterized by enlarged vessels packed with cells. Stasis allows leukocytes to marginate (move) along the endothelium, a process critical to their recruitment into the tissues. Normal flowing blood prevents this, as the shearing force along the periphery of the vessels moves cells in the blood into the middle of the vessel.
== Functions == ATP is derived from ribose; it contains one ribose, three phosphate groups, and an adenine base. ATP is created during cellular respiration from adenosine diphosphate (ATP with one less phosphate group).
Sources: en.wikipedia.org
16 November – The SNP's National Executive Committee proposes cutting the number of staff at its headquarters from 26 to 16. Ruth Maguire, MSP for Cunninghame South, announces she will not seek re-election at the 2026 Scottish Parliament election because she is to undergo treatment for cancer. 17 November – At 12pm, Tesco opens its branch in Stornaway, Isle of Lewis for the first time on a Sunday, the Western Isles being the only place in the UK where the majority of shops remain closed on a Sunday. 19 November – Scottish Labour leader Anas Sarwar says his party will expand the eligibility for winter fuel payments in Scotland if they win the 2026 Scottish Parliament election. Eric Trump, the son of Donald Trump, confirms the US President-elect will visit Scotland in 2025 to open a new golf course. The Scottish Government is reported to be preparing to reduce the minimum term served by prisoners given short sentences, which could lead to the early release of between 260 and 390 prisoners in February 2025. 20 November – The Children and Young People's Commissioner Scotland launches an investigation into Police Scotland's use of force against children. 21 November – Stephen Flynn, the SNP's leader at Westminster, says he will not seek a dual mandate by standing for the Scottish Parliament while he remains an MP. Traditional Scottish singer Iona Fyfe is named as the new Rector of the University of Aberdeen, succeeding Martina Chukwuma–Ezike, and will take up the post on 1 January 2025.
=== Genomic Architecture and Risk of Abdominal Obesity === In addition to the visible changes in adipose tissue associated with obesity, recent research indicates that the risk of developing abdominal obesity and cardiometabolic alterations also depends on the 3D organization of the genome in subcutaneous adipose tissue. Single‑cell epigenomic studies have shown that many genetic variants associated with abdominal fat distribution (measured as WHRadjBMI) are preferentially located in active genomic regions of adipocytes. These regions display low levels of DNA methylation and belong to the so‑called A compartment, which is characterized by higher gene activity. These findings suggest that adipocytes in subcutaneous adipose tissue play a key role in mediating the genetic risk associated with abdominal obesity.
== Diagnosis == Initially diagnosis is typically established by creatine, creatinine, and guanidinoacetate measurement in the plasma, urine, and/or cerebrospinal fluid, as listed in the table below. The levels of these biochemical markers can indicate which specific creatine disorder is present. Brain magnetic resonance spectroscopy can also be used in diagnosis, but will show decreased creatine levels in all three disorders and is therefore unable to identify the specific creatine deficiency disorder. Definitive diagnosis can be found through DNA sequencing of the relevant gene and enzymatic activity (for GAMT and AGAT) or transport activity (CTD).
Sources: en.wikipedia.org
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.
No regulatory agency has approved it for any indication. It is encountered as a research chemical sold outside pharmaceutical supply chains. Products marketed this way are not subject to the manufacturing and labeling requirements that apply to approved drugs.
Reports describe increased skin pigmentation as well as side effects such as nausea, flushing, and changes to existing moles. Much of the evidence comes from small studies and case reports rather than large trials. The long-term safety profile is therefore uncertain.
It is a synthetic cyclic heptapeptide and a non-selective melanocortin receptor agonist. Structurally it is modelled on alpha-melanocyte-stimulating hormone, a peptide that occurs naturally in the body.