Everything below concerns melanocortin receptor. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-10-22. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Compound class | Synthetic cyclic heptapeptide | Alpha-MSH analogue containing a D-phenylalanine residue |
| Molecular formula | C50H69N15O9 | Average molecular mass approximately 1024.2 g/mol |
| Appearance | White to off-white lyophilised powder | Normally supplied as a freeze-dried solid in a sealed vial |
| Solubility | Freely soluble in water and polar solvents | Dissolves readily in aqueous buffers and in alcohol-water mixtures |
| Receptor targets | MC1R, MC3R, MC4R, MC5R | Acts as a non-selective melanocortin receptor agonist |
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.
Two structural changes distinguish the synthetic peptide from the natural hormone. A norleucine residue replaces methionine at one position, and a D-configured phenylalanine replaces the natural L-form at another. Both substitutions slow enzymatic breakdown, which extends the molecule's persistence relative to the parent hormone. The lactam bridge further constrains the backbone into a stable conformation. These features are standard design strategies in peptide chemistry and are not unique to this compound; they appear across many research peptides built for improved stability.
The compound was developed in the late 1980s and early 1990s by academic researchers investigating melanocortin signaling and pigmentation. Early work explored whether synthetic analogs could reproduce effects of the natural hormone under controlled conditions. The molecule never advanced through the full regulatory pathway required for approval as a medicine. From the mid-2000s onward it appeared in unregulated consumer markets, often distributed through informal channels. That gap between research origins and commercial availability shapes how the compound is discussed today.
Melanotan II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
Receptor-binding studies classify melanotan II as a non-selective melanocortin agonist. It interacts with MC1R, MC3R, MC4R and MC5R, with reported affinities in the low nanomolar range and no strong subtype preference. Activation of MC1R on dermal melanocytes shifts pigment synthesis toward eumelanin, the dark polymer deposited in melanosomes and transferred to keratinocytes. Because the same peptide engages MC4R in the hypothalamus, it also appears in animal work on food intake and erectile response, which is why it is discussed in both pigment and metabolic research. Which receptor populations dominate after systemic exposure in humans is not fully established.
=== Surgery === A minimally invasive surgical therapy called serial ultrasound-guided aspiration can be performed to treat breast mastitis in an outpatient setting, achieving a better cosmetic postoperative recovery. On the other side, nipple pain caused by tongue-tie can seek a surgical therapy called frenotomy on infants. In this surgery, the frenulum under the tongue will be clipped to improve latch and remove the restriction of tongue movement. Hence, breastfeeding efficiency can be improved. However, it may not instantly relieve nipple pain since infants probably have developed uncommon tongue movements.
Vital Brazil thus began a series of experimental investigations, and in 1901 he was able to prove that monovalent sera against the Asiatic species were ineffective against South American snakes, and proceeded to develop his first monovalent sera against the most common envenomations in Brazil, those produced by the Bothrops, Crotalus and Elapidae genera (represented respectively by the jararaca snake, the rattlesnake, and the coral snake). He found several clinical and biochemical similarities between bothropic and crotalic envenomations and so he was the first to achieve a polyvalent serum, i.e., simultaneously effective against both species, which represented a triumph over the stark mortality caused by these species in North, Central and South America. In a few decades, this mortality, which was higher than 25% to 20% of bitten people, fell to less than 2%. Applying the same techniques (which involved gradual immunization of horses and sheep by administering small doses of venoms, and then extracting, purifying and freeze-drying the antibody portion from the blood of injected animals), Vital Brazil and his coworkers were able to discover the first sera against two species of scorpions' (1908) and spiders' (1925) venoms. In the USA, Vital Brazil's name made the headlines when he used his serum to save the life of a worker in the Bronx Zoo in New York City who was bitten by a rattlesnake.
8 October Police patrols in London are increased after videos emerge of what appears to be people celebrating a series of attacks launched by Hamas against Israel. Nathanel Young, a 20-year-old British man serving in the Israeli army, is killed in an attack by Hamas militants. The Israeli Embassy in London confirms that British-born Jake Marlowe, who was working in Israel as a security guard, is missing following the previous day's attacks. The final Wilko stores close in the UK. 9 October Sunak chairs an emergency COBRA meeting to discuss the escalating situation in Israel, and pledges further support for the country. The number of dead or missing Britons caught up in the Israel-Gaza attacks rises to more than 10; Nathanel Young and Bernard Cowan are the only two confirmed to have been killed. Addressing the congregation of a London synagogue, Sunak says that Britain stands with Israel, and that he will "stop at nothing" to keep Britain's Jewish community safe. Humza Yousaf, the First Minister of Scotland, condemns the attacks and expresses concern for his in-laws, who are "trapped" in Gaza after travelling there to visit relatives. 10 October In his speech to the Labour Party Conference, Sir Keir Starmer promises NHS reform, more police officers on streets, and 1.5 million new homes. The beginning of the speech is disrupted by a heckler on stage who throws black glitter over Starmer. After making contact with his parents-in-law in Gaza, Humza Yousaf calls for a humanitarian corridor to be established. The UK and Ireland are confirmed as joint hosts of Euro 2028.
Despite never having attended college – or any formal schooling beyond high school – Rathbun had authored more than 80 scientific publications, described over 674 new species of crustacean, and developed a system for crustacean-related records at the Smithsonian Museum. 1917: Dutch biologist and phytopathologist Johanna Westerdijk became the first female university professor in the Netherlands. She was appointed an extraordinary professor of phytopathology at the University of Utrecht. 1918: German physicist and mathematician Emmy Noether created Noether's theorem explaining the connection between symmetry and conservation laws. 1919: Dutch biologist and geneticist Jantina Tammes became the university professor in the Netherlands. She was appointed an extraordinary professor of variability and heredity at the University of Groningen. She became the first person in the Netherlands to occupy a chair in genetic. Moreover, she became the second female professor in the country, and the first one at the University of Groningen. She held this position until 1937, when she resigned at the age of sixty-six. 1919: Chilean engineer Justicia Espada Acuña graduates from Universidad de Chile, becoming the first woman with degree in civil engineering in South America 1919: Kathleen Maisey Curtis became the first New Zealand woman to earn a Doctorate of Science degree (DSc), completing her thesis on Synchytrium endobioticum (potato wart disease) at the Imperial College of Science and Technology.
Sources: en.wikipedia.org
There are three types of muscles—cardiac, skeletal, and smooth. Smooth muscles are used to control the flow of substances within the lumens of hollow organs, and are not consciously controlled. Skeletal and cardiac muscles have striations that are visible under a microscope due to the components within their cells. Only skeletal and smooth muscles are part of the musculoskeletal system and only the muscles can move the body. Cardiac muscles are found in the heart and are used only to circulate blood; like the smooth muscles, these muscles are not under conscious control. Skeletal muscles are attached to bones and arranged in opposing groups around joints. Muscles are innervated, whereby nervous signals are communicated by nerves, which conduct electrical currents from the central nervous system and cause the muscles to contract.
== Signs and symptoms == Generally, the majority of individuals with creatine transporter defect express the following symptoms with varying levels of severity: developmental delay and regression, intellectual disability, and abnormalities in expressive and cognitive speech. However, several studies have shown a wider variety of symptoms including, but not limited to attention deficit and hyperactivity with impulsivity, myopathy, hypotonia, semantic-pragmatic language disorder, oral dyspraxia, extrapyramidal movement disorder, constipation, absent speech development, seizures, and epilepsy. Furthermore, symptoms can significantly vary between hemizygous males and heterozygous females, although, symptoms are generally more severe in hemizygous males. Hemizygous males more commonly express seizures, growth deficiency, severe intellectual disability, and severe expressive language impairment. Heterozygous females more commonly express mild intellectual disability, impairments to confrontational naming and verbal memory, and learning and behavior problems.
the Secretary mentioned that he was being pressed by the Foreign Office to bring forward the question of Zionism, an early settlement of which was regarded as of great importance." 31 October 1917: "[Balfour] stated that he gathered that everyone was now agreed that, from a purely diplomatic and political point of view, it was desirable that some declaration favourable to the aspirations of the Jewish nationalists should now be made. The vast majority of Jews in Russia and America, as, indeed, all over the world, now appeared to be favourable to Zionism. If we could make a declaration favourable to such an ideal, we should be able to carry on extremely useful propaganda both in Russia and America."
Like most alchemical terms, the word "Sulfur" came to mean a lot of different things in alchemical works beyond its standard definition, representing concepts such as the active, masculine or fixing principle, combustion, or the soul. There were multiple "sulfurs", as the word was used as a Deckname, a secret codename for other substances.
He also stated that "Nations should not be punished in place of terrorists." According to Radio Farda's website, when the news of the attacks was released, some Iranian citizens gathered in front of the Embassy of Switzerland in Tehran, which serves as the protecting power of the United States in Iran, to express their sympathy, and some of them lit candles as a symbol of mourning. Radio Farda's website also states that in 2011, on the anniversary of the attacks, the United States Department of State published a post on its blog, in which the Department thanked the Iranian people for their sympathy and stated that it would never forget Iranian people's kindness. After the attacks, both the President and the Supreme Leader of Iran condemned the attacks. The BBC and Time magazine published reports on holding candlelit vigils for the victims by Iranian citizens on their websites. According to Politico Magazine, following the attacks, Ali Khamenei, the Supreme Leader of Iran, "suspended the usual 'Death to America' chants at Friday prayers" temporarily.
Sources: en.wikipedia.org
== External links == Examination of Leonardo da Vinci's Madonna of the Yarnwinder using PIXE[link removed] Application of PIXE to the study of Renaissance style enameled gold jewelry (PDF) PDI-PIXE-MS: Particle Desorption Ionization Particle-Induced X-Ray Emission Mass Spectrometry (PDF) PIXEMS PNNL031209 – Pacific Northwest National Laboratory Presentation – "Particle Desorption Ionization Particle-Induced X-Ray Emission Mass Spectrometry" – PDI-PIXE-MS. (PDF) Sproch, N., Ashbaugh, M.D., Morse, D., Grant, P., McIntyre Jr., L.C., Antolak, A., Fernando, Q., "PD/PIXE-MS: Particle Desorption Particle Induced X-ray Emission Mass Spectrometry", Proceedings of the 49th ASMS Conference on Mass Spectrometry and Allied Topics; Chicago, Il, May 27 – May 31, 2001.
United Parcel Service, Inc. (UPS) is an American multinational shipping-and-receiving and supply chain management company founded in 1907. Originally known as the American Messenger Company specializing in telegraphs, UPS has expanded to become a Fortune 500 company and one of the world's largest shipping couriers. UPS today is primarily known for its ground shipping services as well as the UPS Store, a retail chain which assists UPS shipments and provides tools for small businesses. UPS offers air shipping on an overnight or two-day basis and delivers to post office boxes through UPS Mail Innovations and UPS Ground Saver. UPS is the largest courier company in the world by revenue, with annual revenues around US$85 billion in 2020, ahead of competitors DHL and FedEx. UPS's main international hub, UPS Worldport in Louisville, Kentucky, is the fifth busiest airport in the world by cargo traffic based on preliminary statistics from ACI, and the third busiest in the U.S. The company is one of the largest private employers in the United States. As of 2023, UPS is third in U.S. parcel volumes shipped since 2015, trailing the United States Postal Service and Amazon.
Before leaving for the Philippines, the men received further instructions and physical examinations in Camp Stoneman in Pittsburg, California, in March 1945. The men left for the Philippines on the troop ship S.S. Fairisle on March 27, 1945. The squadron arrived in Manila on April 30, 1945, and was assigned to the Fifth Air Force's 58th Fighter Group, based at Porac, Pampanga, in the Clark Field complex on the island of Luzon. Thus, the 201st Squadron of the Mexican Expeditionary Air Force, composed of about 300 men, 30 pilots and 25 U.S.-made P-47D Thunderbolt aircraft, fought against Imperial Japanese Army forces during the Battle of Luzon in pursuit of the liberation of the Philippines. The P-47D aircraft carried USAAF insignia but with Mexican colors on the tail rudder.
extensive wounding or trauma burns areas of extensive skin loss due to infection such as necrotizing fasciitis or purpura fulminans specific surgeries that may require skin grafts for healing to occur – most commonly removal of skin cancers Skin grafting often takes place after serious injuries when some of the body's skin is damaged. Surgical removal (excision or debridement) of the damaged skin is followed by skin grafting. The grafting serves two purposes: reducing the course of treatment needed (and time in the hospital), and improving the function and appearance of the area of the body which receives the skin graft. There are two types of skin grafts:
Sources: en.wikipedia.org
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.
No approved regulatory indication exists in major markets. An approval exists for a different peptide, afamelanotide, which is used for a rare photosensitivity disorder called erythropoietic protoporphyria. Melanotan-2 itself remains a research compound with no cleared clinical role.
Melanocortin-1 receptors on melanocytes are the receptor most closely linked to pigment production. The peptide is not selective, however, and also activates melanocortin-3, melanocortin-4, and melanocortin-5 receptors. That lack of selectivity is the usual explanation offered for both its range of observed effects and its off-target effects.
No regulator in a major market has approved it for human use. It appears in research settings and in products marketed outside pharmacy channels. Legal status for personal possession varies by country.