MC1R is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-06-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
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controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports.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.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
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 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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Alpha-MSH analogue with a lactam ring |
| Molecular formula | C50H69N15O9 | Commonly cited value for the neutral peptide |
| Molecular weight | 1024.18 g/mol | Calculated for the free molecule |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water, DMSO and ethanol | Dissolution in pure water is often slow |
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.
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.
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.
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
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.
. For this ionization pathway, the gas-phase acidity of the protonated water clusters and the gas-phase basicity of the analyte molecule are of crucial importance. However, since especially smaller protonated water clusters with n = 1,2,3... exhibit very high gas-phase acidities, even compounds with a rather low gas-phase basicity are readily ionized by proton transfer, yielding [M+H]+ quasimolecular ions. Besides protonated water clusters, other positively charged reagent ions, such as NO+, O2+, NO2+ and CO2+, may be formed in the afterglow region. These additional reagent ions are capable of ionizing compounds via charge-transfer processes and, thus, offer alternative routes of ionization besides proton transfer, leading to a broader range of suitable analytes. Nevertheless, these ionization mechanisms may also lead to the formation of adducts and oxidation of the original analyte compounds.
Wolpaw and Pinkerton turned down invitations to return to Valve early in the Alyx development. Instead, Valve recruited Rob Yescombe of The Invisible Hours, who worked on Alyx in 2017 and 2018. Yescombe's narrative was darker than previous Half-Life games, with scenes of dread, torture and horror. The antagonist was a female Combine officer named Hahn; in one proposed ending, Alyx would kill Hahn in revenge for torturing her father. Yescombe also proposed an ending in which Alyx and the G-Man would travel back in time to the events of the first Half-Life to prevent Freeman from triggering the alien invasion. After the company-wide playtest in 2018, feedback was overwhelmingly positive save for the story, which employees scored the lowest of any Valve game. Morasky described it as "dark, serious and laborious", likening it to a Zack Snyder superhero film. The designer Corey Peters said the feedback vindicated their misgivings. Valve initially planned to launch Alyx alongside its Index VR headset in June 2019, but delayed it to address the story. They re-enlisted Wolpaw and Pinkerton to rewrite the plot and dialogue while preserving the gameplay, along with Jake Rodkin and Sean Vanaman, who had joined when Valve acquired Campo Santo. Laidlaw, who retired in 2016, denied reports that he had provided consultation, saying he had confidence in Pinkerton and Wolpaw and that he did not want them "second-guessing" him. The new writing team identified three problems. First, the nature of a prequel meant that players knew the characters would survive, reducing suspense.
It is approved as an antimanic and antiseizure in Japan as well. In UK, valproate is approved for bipolar mania and epilepsy, and both valproate and divalproex are approved, although divalproex sodium is known as valproate semisodium. Valproate's precise mechanism of action is unclear. Proposed mechanisms include affecting GABA levels, blocking voltage-gated sodium channels, inhibiting histone deacetylases, and increasing LEF1. Valproic acid is a branched short-chain fatty acid (SCFA), a derivative of valeric acid. Valproate was originally synthesized in 1881 and came into medical use in 1962. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication. In 2023, it was the 160th most commonly prescribed medication in the United States, with more than 3 million prescriptions.
DNA can be manipulated in the laboratory. Restriction enzymes are commonly used enzymes that cut DNA at specific sequences, producing predictable fragments of DNA. DNA fragments can be visualized through use of gel electrophoresis, which separates fragments according to their length. The use of ligation enzymes allows DNA fragments to be connected. By binding ("ligating") fragments of DNA together from different sources, researchers can create recombinant DNA, the DNA often associated with genetically modified organisms. Recombinant DNA is commonly used in the context of plasmids: short circular DNA molecules with a few genes on them. In the process known as molecular cloning, researchers can amplify the DNA fragments by inserting plasmids into bacteria and then culturing them on plates of agar (to isolate clones of bacteria cells). "Cloning" can also refer to the various means of creating cloned ("clonal") organisms. DNA can also be amplified using a procedure called the polymerase chain reaction (PCR). By using specific short sequences of DNA, PCR can isolate and exponentially amplify a targeted region of DNA. Because it can amplify from extremely small amounts of DNA, PCR is also often used to detect the presence of specific DNA sequences.
Sources: en.wikipedia.org
Diagnosis of barotrauma generally involves a history of exposure to a source of pressure which could cause the injury suggested by the symptoms. This can vary from the immediately obvious if exposed to explosive blast, or mask squeeze, to rather complex discrimination between possibilities of inner ear decompression sickness and inner ear barotrauma, which may have nearly identical symptoms but different causative mechanism and mutually incompatible treatments. The detailed dive history may be necessary in these cases. In terms of barotrauma the diagnostic workup for the affected individual could include the following: Laboratory:
==== Dol ==== The dol (from the Latin word for pain, dolor) is a unit of measurement for pain. James D. Hardy, Herbert G. Wolff, and Helen Goodell of Cornell University proposed the unit based on their studies of pain during the 1940s and 1950s. They defined one dol to equal a just-noticeable difference in pain. The unit never came into widespread use and other methods are now used to assess the level of pain experienced by patients.
The temperature gradient gel electrophoresis (TGGE) or temperature gradient capillary electrophoresis (TGCE) method is based on the principle that partially denatured DNA is more restricted and travels slower in a porous material such as a gel. This property allows for the separation of DNA by melting temperature. To adapt these methods for SNP detection, two fragments are used; the target DNA which contain the SNP polymorphic site being interrogated and an allele-specific DNA sequence, referred to as the normal DNA fragment. The normal fragment is identical to the target DNA except potentially at the SNP polymorphic site, which is unknown in the target DNA. The fragments are denatured and then reannealed. If the target DNA has the same allele as the normal fragment, homoduplexes will form that will have the same melting temperature. When run on the gel with a temperature gradient, only one band will appear. If the target DNA has a distinct allele, four products will form following the reannealing step; homoduplexes consisting of target DNA, homoduplexes consisting of normal DNA and two heterduplexes of each strand of target DNA hybridized with the normal DNA strand. These four products will have distinct melting temperatures and will appear as four bands in the denaturing gel.
Moore supports a balance between securing the United States' borders and creating pathways to citizenship for those already in the country. In June 2023, Moore said that he supported efforts to strengthen the federal temporary protected status policy for immigrants living in the United States. In June 2024, after a man who had entered the United States illegally was arrested in connection with the murder of Rachel Morin, Moore blamed congressional inaction on the issue of immigration as well as conditions at the Mexico–United States border for Morin's killing. In June 2023, after multiple Republican governors sent members of their state national guards to the southern border, Moore told WRC-TV that he did not support sending members of the Maryland National Guard to the border. In January 2025, he declined to say if he would deploy Maryland National Guard members at the southern border if asked by the federal government. Moore also advised local jurisdictions to "follow the Constitution" when cooperating with federal immigration efforts. In May 2025, he signed into law the Maryland Values Act, which prohibits federal law enforcement from conducting immigration actions at sensitive locations. In April 2025, Moore condemned the Trump administration's deportation of Kilmar Abrego Garcia on the grounds of inadequate due process, saying that "no one should be deported to the very county where a judge determined they will face persecution" and calling on the federal government to "correct" their error.
=== Wound healing === Aroa Biosurgery Limited first distributed OFM commercially in 2012 as Endoform™ Dermal Template (later Endoform™ Natural) through a distribution partnership with Hollister Incorporated (IL, USA). Endoform™ Natural and Endoform™ Antimicrobial (0.3% ionic silver w/w), are single layers of OFM used in the treatment of acute and chronic wounds, including diabetic foot ulcers (DFU) and venous leg ulcers (VLU). Endoform™ Natural has been shown to accelerate wound healing of DFU. The wound product Symphony™ combines OFM and hyaluronic acid and is designed to support healing during the proliferative phase particularly in patients whose healing is severely impaired or compromised due to disease.
Sources: en.wikipedia.org
=== Breast cancer === Hormone antagonists are used widely in anticancer treatments, such as the drug tamoxifen, an anti-estrogen that binds to estrogen receptors to slow the growth of some estrogen receptor-positive breast cancers. Aromatase inhibitors (AIs) are also prescribed as a breast cancer treatment, especially after mastectomies. AIs work by blocking the action of the aromatase enzyme, which converts androgens, like testosterone, into estrogen. Aromatase inhibitors can be used in conjunction with estrogen receptor inhibitors to treat estrogen receptor-positive breast cancers in women who have gone through menopause already.
=== March === 3 March – The GMB and Unison unions have called off ambulance strikes in England scheduled for 6 and 8 March after the UK government agrees to reopen talks on pay for the 2022–23 and 2023–24 financial years. Following a trial at Luton Crown Court, four people are jailed for their part in a robbery that went wrong during which their victim, Saul Murray, was stabbed after being given the drug GHB in an attempt to knock him out. Ikem Affia is sentenced to life imprisonment for murder, with a minimum of 25 years, while the three other gang members are given lesser sentences for manslaughter. The gang were caught after one of them was captured on CCTV wearing a rare Moncler coat worth £1,000, of which only 69 had been sold in the UK. 5 March – The Unite union calls off ambulance strikes scheduled for 6 and 8 March. 8 March – The National Institute for Health and Care Excellence (NICE) approves the use of the weight loss drug semaglutide (marketed as Wegovy) by the NHS in England. 13 March – The Unite union calls off a planned strike by bus drivers at National Express West Midlands scheduled for 16 March after receiving a revised pay offer, which is to be put to members. 16 March – NHS staff in England, including nurses and ambulance staff, are offered a 5% pay rise from April along with a one-off payment of £1,655 to cover backdated pay. The offer does not include doctors, who are on a different contract.
The first SPR immunoassay was proposed in 1983 by Liedberg, Nylander, and Lundström, then of the Linköping Institute of Technology (Sweden). They adsorbed human IgG onto a 600-Ångström silver film, and used the assay to detect anti-human IgG in water solution. Unlike many other immunoassays, such as ELISA, an SPR immunoassay is label free in that a label molecule is not required for detection of the analyte. Additionally, the measurements on SPR can be followed real-time allowing the monitoring of individual steps in sequential binding events particularly useful in the assessment of for instance sandwich complexes.
In Filipino cuisine, the noodles are called a similar name: sotanghon because of the popular dish of the same name made from them using chicken and wood ears. They are also confused with rice vermicelli, which is called bihon in the Philippines.
Breast Acute myeloid leukemia Pancreatic ductal adenocarcinoma Ovarian B-cell lymphoma Renal cell carcinomas Lung Glioblastoma These forms of cancer have been hypothesized to be highly sensitive to ferroptosis induction. An upregulation of iron levels has also been seen to induce ferroptosis in certain types of cancer, such as breast cancer. Breast cancer cells have exhibited vulnerability to ferroptosis via a combination of siramesine and lapatinib. These cells also exhibited an autophagic cycle independent of ferroptotic activity, indicating that the two different forms of cell death could be controlled to activate at specific times following treatment. Furthermore, intratumor bacteria may scavenge iron by producing iron siderophores, which indirectly protect tumor cells from ferroptosis, emphasizing the need for ferroptosis inducers (thiostrepton) for cancer treatment. In various contexts, resistance to cancer therapy is associated with a mesenchymal state. A pair of studies in 2017 found that these cancer cells in this therapy-induced drug-resistant state exhibit a greater dependence on GPX4 to suppress ferroptosis. Consequently, GPX4 inhibition represents a possible therapeutic strategy to mitigate acquired drug resistance.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.
No national medicines agency has approved melanotan-2 for clinical use. Afamelanotide, a related but distinct peptide, holds a marketing authorisation in the European Union for a rare photosensitivity disorder. Melanotan-2 itself is handled as a laboratory chemical.
Its broad activity across melanocortin receptors makes it a tool for probing pigmentation, appetite and vascular signalling. Early trials recorded skin darkening and other effects that were not the original focus of the work. Those observations generated hypotheses that later studies have examined.
No regulatory agency has authorised melanotan-2 as a medicine for any indication. It circulates mainly as a research chemical or through unregulated channels. As a result, identity, purity and content are not independently guaranteed.