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.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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 |
|---|---|---|
| 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 |
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.
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.
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.
Some infections, for example, those from the common cold and influenza, do not confer any long-lasting immunity. Such infections may give temporary resistance but do not give long-term immunity upon recovery from infection, and individuals become susceptible again.
An outbreak of avian botulism leads to the deaths of about 1,000 birds at the Waikouaiti wastewater treatment plant near Dunedin and the Washdyke Lagoon near Timaru. 27 January – New Zealand Foreign Minister Winston Peters' suspends New Zealand's aid programme to Kiribati after Kiribati President Taneti Maamau cancelled three pre-arranged meetings including one scheduled for mid January 2025. The New Zealand Government had wanted to discuss how NZ$102 million worth of aid money allocated to Kiribati between 2021 and 2024 was being spent. 29 January: Prime Minister Luxon and Transport Minister Chris Bishop announces plans by the Government to reverse blanket speed limits on 38 sections of the New Zealand state highway network and seek public consultation on raising the speed limits for another 49 state highway sections. Advocacy group Toitū te Tiriti files an urgent Waitangi Tribunal claim against proposed Regulatory Standards Bill, claiming it would undermine the Treaty of Waitangi. 30 January: Mount Taranaki is officially recognised as a person under the name Taranaki Maunga. The $130 million Queenstown Town Centre arterial road opens. 31 January: Health Minister Simeon Brown confirms that a new Dunedin Hospital will be built on the site of the former Cadbury factory at a cost of NZ$1.9 billion. A power outage affects 22,000 Transpower customers in Rotorua. The Royal New Zealand Air Force formally retires its fleet of five C-130H Hercules planes.
== Advantages == Although fluorescent dyes may not have the same sensitivity as radioactive probes, they are able to show real-time activity of molecules in action. Moreover, radiation and appropriate handling is no longer a concern. With the development of fluorescent tagging, fluorescence microscopy has allowed the visualization of specific proteins in both fixed and live cell images. Localization of specific proteins has led to important concepts in cellular biology such as the functions of distinct groups of proteins in cellular membranes and organelles. In live cell imaging, fluorescent tags enable movements of proteins and their interactions to be monitored. Latest advances in methods involving fluorescent tags have led to the visualization of mRNA and its localization within various organisms. Live cell imaging of RNA can be achieved by introducing synthesized RNA that is chemically coupled with a fluorescent tag into living cells by microinjection. This technique was used to show how the oskar mRNA in the Drosophila embryo localizes to the posterior region of the oocyte.
7 December Storm Darragh: Hundreds of thousands are left without power, while travel is disrupted and many planned events are called off, as winds of up to 93 mph (150 km/h) hit much of the UK, along with heavy rain. A rare red weather warning is in place in Wales and south-west England, meaning the storm poses a risk to life. The deaths of two men are reported, in Birmingham and Lancashire, due to trees falling on vehicles. A 61-year-old Elizabeth line worker dies following a serious assault at Ilford railway station on 4 December. A 28-year-old man is charged with grievous bodily harm, affray, and possession of a prohibited offensive weapon. 8 December Prime Minister Sir Keir Starmer welcomes the Fall of the Assad regime in Syria, which he describes as "barbaric", and calls for the restoration of "peace and stability". Emma Pinchbeck, the new chief executive of the UK government's Climate Change Committee, says the UK is "not ready" for the kind of extreme weather brought by Storm Darragh. Prince William helps to serve lunch at The Passage, a London-based homeless charity he first visited with his mother as a boy. 9 December – The UK pauses asylum claims from Syrian refugees following the overthrow of Bashar al-Assad. 10 December The UK government recommends a 2.8% pay rise for public sector workers from April 2025. In response, the Unison trade union describes the offer as "barely above the cost of living". King Charles III presents the first Elizabeth Emblems, recognising public servants such as police officers and firefighters who died while on duty.
== Uses == The plant is grown in the Taklamakan Desert, and is traditionally used for medicines and foods in China. The main sources of the Chinese herbal medicine cistanche (Chinese: 肉苁蓉, pinyin ròucōngróng) are Cistanche salsa and Cistanche deserticola, although it may also be obtained from C. tubulosa. The drug, known in Chinese as suosuo dayun, is collected in spring before sprouting, by slicing the stems of the plant.
Sources: en.wikipedia.org
Maridebart cafraglutide (also known as MariTide; developmental name AMG 133) is an investigational drug developed by Amgen for the treatment of obesity. It is an agonist of the GLP-1 receptor (GLP-1R) and an antagonist of the glucose-dependent insulinotropic polypeptide receptor (GIPR). Namely, MariTide consists of a monoclonal antibody against GIPR conjugated to two peptidic GLP-1R agonist molecules via amino acid linkers. In a preliminary trial, AMG 133 resulted in a 14.5 percent weight loss after 12 weeks at the highest dose tested.
Timothy C. Bates (born 1963) is a professor of differential psychology at the University of Edinburgh. His research interests include the genetics of reading and spelling, intelligence, and personality.
==== 2200–2299 ==== Motor Vehicles (Type Approval for Goods Vehicles) (Great Britain) (Amendment) Regulations 1993 (S.I. 1993/2200) Motor Vehicles (Type Approval) (Great Britain) (Amendment) Regulations 1993 (S.I. 1993/2201) Bananas (Interim Measures) (Revocation) Regulations 1993 (S.I. 1993/2204) Wireless Telegraphy (Television Licence Fees) (Amendment) (No. 2) Regulations 1993 (S.I. 1993/2205) National Health Service (General Dental Services) Amendment Regulations 1993 (S.I. 1993/2209) Dental Vocational Training Authority Regulations 1993 (S.I. 1993/2210) Dental Vocational Training Authority (Establishment and Constitution) and Appeal Body (Specification) Order 1993 (S.I. 1993/2211) Taxes (Interest Rate) (Amendment No. 3) Regulations 1993 (S.I. 1993/2212) Friendly Societies Act 1992 (Commencement No. 6 and Transitional Provisions) Order 1993 (S.I. 1993/2213) Finance Act 1993 (Appointed Day) Order 1993 (S.I. 1993/2214) Finance Act 1993, section 12, (Appointed Day) Order 1993 (S.I. 1993/2215) National Health Service (District Health Authorities) (No.2) Order 1993 (S.I. 1993/2218) National Health Service (Determination of Districts) (No.2) Order 1993 (S.I. 1993/2219) National Health Service (General Dental Services) (Scotland) Amendment Regulations 1993 (S.I. 1993/2224) Parole Board (Scotland) Rules 1993 (S.I. 1993/2225) Transcripts of Criminal Proceedings (Scotland) Order 1993 (S.I. 1993/2226) Prison (Scotland) Amendment Rules 1993 (S.I. 1993/2227) Young Offenders (Scotland) Amendment Rules 1993 (S.I. 1993/2228) Road Traffic Act 1991 (Commencement No.
=== Methods of assessment === An increase in prothrombin time, a coagulation assay, has been used as an indicator of vitamin K status, but it lacks sufficient sensitivity and specificity for this application. Serum phylloquinone is the most commonly used marker of vitamin K status. Concentrations <0.15 μg/L are indicative of deficiency. Disadvantages include exclusion of the other vitamin K vitamers and interference from recent dietary intake. Vitamin K is required for the gamma-carboxylation of specific glutamic acid residues within the Gla domain of the 17 vitamin K–dependent proteins. Thus, a rise in uncarboxylated versions of these proteins is an indirect but sensitive and specific marker for vitamin K deficiency.
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 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.