A practical reference on alpha-MSH analogue: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-07-26 and is reviewed periodically as new material appears.
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.
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-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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Melanocortin receptor agonist |
| Molecular formula | C50H69N15O9 | Neutral form, mass near 1024.2 g/mol |
| Primary targets | MC1R, MC3R, MC4R, MC5R | Binding is non-selective across subtypes |
| Related compounds | Alpha-MSH, melanotan I, afamelanotide | Structurally or functionally related peptides |
| Common abbreviations | MT-II, MT-2 | Naming in the literature is not uniform |
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.
Melanotan II binds several melanocortin receptor subtypes rather than a single target. MC1R on melanocytes drives melanin synthesis, while MC3R and MC4R participate in energy balance, appetite, and sexual response pathways. This lack of selectivity explains why reported effects extend beyond skin darkening. Substitutions at positions four and seven, including norleucine and D-phenylalanine, increase potency and resistance to peptidases. Understanding which receptor mediates which effect remains an active area of investigation.
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.
Vampire: The Masquerade – Bloodlines was released on November 16, 2004, in competition with Half-Life 2, Metal Gear Solid 3: Snake Eater, Halo 2, and several other titles. Valve's contract for Troika's use of the Source engine guaranteed that Bloodlines could not be released before Half-Life 2 and could not be introduced to the public until after the announcement of Half-Life 2, over eighteen months after development began. In February 2004, the game was scheduled for release in spring 2005, partially to avoid competing with Half-Life 2 and the competitive Christmas period, before Activision moved the date to November 2004. Activision obtained model Erin Layne to play Jeanette in promotional material for the game. Layne worked with Bloodlines artist Tim Bradstreet for a day to provide the poses chosen by Activision to represent Jeanette in the game's posters, clothing, and other items. Despite generally favorable reviews, Bloodlines' initial release sold 72,000 copies and earned approximately US$3.4 million in sales, below Troika's other games, Arcanum: Of Steamworks and Magick Obscura (234,000 units, $8.8 million) and The Temple of Elemental Evil (128,000 units, $5.2 million). In comparison, Bloodlines' release competitor Half-Life 2 had sold 6.5 million copies by 2008. Bloodlines' relative failure contributed to the demise of Troika Games. Shortly after its debut, most development staff were laid off; the remaining staff tried to patch Bloodlines and develop game concepts to secure funding to keep Troika in business.
== External links == Clinical trial number NCT05662332 for "A Study of Insulin Efsitora Alfa (LY3209590) Compared to Glargine in Adult Participants With Type 2 Diabetes Who Are Starting Basal Insulin for the First Time (QWINT-1) (QWINT-1)" at ClinicalTrials.gov Clinical trial number NCT05362058 for "A Study of Insulin Efsitora Alfa (LY3209590) Compared to Degludec in Adults With Type 2 Diabetes Who Are Starting Basal Insulin for the First Time (QWINT-2)" at ClinicalTrials.gov Clinical trial number NCT05275400 for "A Study of Insulin Efsitora Alfa (LY3209590) Compared With Insulin Degludec in Participants With Type 2 Diabetes Currently Treated With Basal Insulin" at ClinicalTrials.gov Clinical trial number NCT05462756 for "A Study of Insulin Efsitora Alfa (LY3209590) as a Weekly Basal Insulin Compared to Insulin Glargine in Adult Participants With Type 2 Diabetes on Multiple Daily Injections (QWINT-4)" at ClinicalTrials.gov
=== Controversy === In 2015, ex-Transportation corps commander Major General Liu Zhanqi, ex-Transportation corps Political commissar Major General Wang Xin and ex-Transportation Corps Chief engineer Major General Miao Guirong were arrested on 16 June, 31 July and 15 September respectively on corruption-related charges as part of the anti-corruption campaign under Xi Jinping. As of 16 September 2015, a total of 43 people were arrested in relation to the case.
Sources: en.wikipedia.org
=== miRNA === MicroRNAs (miRNAs) have complementary sequences in the 3' UTR and 5' UTR of target mRNAs of protein-coding genes, and cause mRNA cleavage or repression of translational machinery. In diseased vascular vessels, miRNAs are dysregulated and highly expressed. miR-33 is found in cardiovascular diseases. It is involved in atherosclerotic initiation and progression including lipid metabolism, insulin signaling and glucose homeostatis, cell type progression and proliferation, and myeloid cell differentiation. They found in rodents that the inhibition of miR-33 raises HDL-C levels, and miR-33 expression is down-regulated in humans with atherosclerotic plaques. miR-33a and miR-33b are located on intron 16 of human sterol regulatory element-binding protein 2 (SREBP2) gene on chromosome 22 and intron 17 of SREBP1 gene on chromosome 17. miR-33a/b regulates cholesterol/lipid homeostasis by binding in the 3'UTRs of genes involved in cholesterol transport, such as ATP binding cassette (ABC) transporters, and enhances or represses their expression. Studies have shown that ABCA1 mediates cholesterol transport from peripheral tissues to Apolipoprotein-1. It is also important in the reverse cholesterol transport pathway, where cholesterol is delivered from peripheral tissue to the liver, where it can be excreted into bile or converted to bile acids before excretion. Therefore, ABCA1 prevents cholesterol accumulation in macrophages. By enhancing miR-33 function, ABCA1 levels decrease, leading to decreased cellular cholesterol efflux to apoA-1.
Nanocomposites are desirable for their mechanical properties. When fillers in a composite are at the nanometer length scale, the surface to volume ratio of the filler material is high, which influences the bulk properties of the composite more compared to traditional composites. The properties of these nanosized elements is markedly different from that of its bulk constituent. In regards to natural fibers, some of the best example of nanocomposites appear in biology. Bone, abalone shell, nacre, and tooth enamel are all nanocomposites. As of 2010, most synthetic polymer nanocomposites exhibit inferior toughness and mechanical properties compared to biological nanocomposites. Completely synthetic nanocomposites do exist, however nanosized biopolymers are also being tested in synthetic matrices. Several types of protein based, nanosized fibers are being used in nanocomposites. These include collagen, cellulose, chitin and tunican. These structural proteins must be processed before use in composites. To use cellulose as an example, semicrystalline microfibrils are sheared in the amorphous region, resulting in microcrystalline cellulose (MCC). These small, crystalline cellulose fibrils are at this points reclassified as a whisker and can be 2 to 20 nm in diameter with shapes ranging from spherical to cylindrical. Whiskers of collagen, chitin, and cellulose have all been used to make biological nanocomposites. The matrix of these composites are commonly hydrophobic synthetic polymers such as polyethylene, and polyvinyl chloride and copolymers of polystyrene and polyacrylate.
== External links == Cartilage.org, International Cartilage Regeneration & Joint Preservation Society KUMC.edu Archived 2011-04-08 at the Wayback Machine, Cartilage tutorial, University of Kansas Medical Center Bartleby.com, text from Gray's anatomy MadSci.org, I've heard 'Ears and nose do not ever stop growing.' Is this false? CartilageHealth.com, Information on Articular Cartilage Injury Prevention, Repair and Rehabilitation About.com Archived 2011-07-07 at the Wayback Machine, Osteoarthritis Cartilage types[link removed] Different cartilages on TheFreeDictionary Cartilage photomicrographs
Sources: en.wikipedia.org
Thrombotic thrombocytopenic purpura - uncommon and potentially fatal thrombotic microangiopathy characterized by severe thrombocytopenia, organ ischemia connected to diffuse microvascular platelet rich-thrombi, and microangiopathic hemolytic anemia. Relapsing polychondritis - uncommon multisystem autoimmune disease with an unclear etiology that is marked by progressive cartilaginous tissue loss and recurring episodes of inflammation. Mixed connective tissue disease - systemic autoimmune disease that shares characteristics with two or more other systemic autoimmune diseases, such as rheumatoid arthritis, polymyositis/dermatomyositis, systemic lupus erythematosus, and systemic sclerosis. It is an example of overlap syndrome. Undifferentiated connective tissue disease - unclassifiable systemic autoimmune disorders that do not meet any of the current classification requirements for connective tissue diseases, yet have clinical and serological signs similar to connective tissue diseases. Psoriatic arthritis - inflammatory musculoskeletal condition linked to psoriasis. Cryoglobulinemia - condition sometimes associated with systemic lupus erythematosus or rheumatoid arthritis in which there are abnormal proteins in the blood. IgG4-related disease - chronic inflammatory condition in which there is deposition of connective tissue (fibrosis) in different organs. Potentially life-threatening. Periaortitis - a group of rare vascular inflammatory diseases in which fibrous inflammatory tissue develops around the aorta or other structures such as the ureters.
Americium is used in the most common type of household smoke detector, which uses 241Am in the form of americium dioxide as its source of ionizing radiation. This isotope is preferred over 226Ra because it emits 5 times more alpha particles and relatively little harmful gamma radiation. The amount of americium in a typical new smoke detector is 1 microcurie (37 kBq) or 0.29 microgram. This amount declines slowly as the americium decays into neptunium-237, a different transuranic element with a much longer half-life (about 2.14 million years). With its half-life of 432.2 years, the americium in a smoke detector includes about 3% neptunium after 19 years, and about 5% after 32 years. The radiation passes through an ionization chamber, an air-filled space between two electrodes, and permits a small, constant current between the electrodes. Any smoke that enters the chamber absorbs the alpha particles, which reduces the ionization and affects this current, triggering the alarm. Compared to the alternative optical smoke detector, the ionization smoke detector is cheaper and can detect particles which are too small to produce significant light scattering; however, it is more prone to false alarms.
Psychiatric diagnoses take place in a wide variety of settings and are performed by many different health professionals. Therefore, the diagnostic procedure may vary greatly based upon these factors. Typically, though, a psychiatric diagnosis utilizes a differential diagnosis procedure where a mental status examination and physical examination is conducted, with pathological, psychopathological or psychosocial histories obtained, and sometimes neuroimages or other neurophysiological measurements are taken, or personality tests or cognitive tests administered. In some cases, a brain scan might be used to rule out other medical illnesses, but at this time relying on brain scans alone cannot accurately diagnose a mental illness or tell the risk of getting a mental illness in the future. Some clinicians are beginning to utilize genetics and automated speech assessment during the diagnostic process but on the whole these remain research topics.
Charles Richard Drew (June 3, 1904 – April 1, 1950) was an American surgeon and medical researcher. He researched in the field of blood transfusions, developing improved techniques for blood storage, and applied his expert knowledge to developing large-scale blood banks early in World War II. This allowed medics to save thousands of Allied forces' lives during the war. As the most prominent African American in the field, Drew protested against the practice of racial segregation in the donation of blood, as it lacked scientific foundation, and resigned his position with the American Red Cross, which maintained the policy until 1950.
Sources: en.wikipedia.org
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.
Activation of MC1R increases pigment synthesis independently of ultraviolet exposure, which is the mechanism usually cited for darkening without sun exposure. Ultraviolet light still influences skin response through separate biological pathways.
Because the peptide binds several melanocortin receptor subtypes, its effects are not confined to pigmentation. This complicates interpretation of both intended and unintended outcomes reported in studies.
No. It is a laboratory-made peptide, while the natural hormone is alpha-melanocyte-stimulating hormone, a longer peptide produced by the pituitary gland and by skin cells. Melanotan-2 mimics only a short active region of that hormone and contains non-natural residues such as D-phenylalanine.