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 2026-04-12. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Lyophilized peptide powder is generally stored frozen, protected from light and moisture. Tryptophan residues are susceptible to oxidation, and the lactam bridge can hydrolyze under strongly acidic or basic conditions. Solutions prepared for laboratory work degrade faster than dry powder, and repeated freeze-thaw cycles accelerate loss. Common practice is to aliquot solutions before freezing and to avoid alkaline buffers. Reported stability windows vary with concentration, buffer, and temperature, so exact shelf lives are method-specific rather than universal.
Regulatory status differs by country, and in many places supplying the compound for human consumption is unlawful. Vendors frequently label material as intended for research use only, a designation that shifts stated purpose but does not create a legal pathway for personal use. Certificates of analysis accompanying such products vary widely in detail and provenance. Third-party testing exists but is voluntary, and results are rarely linked to a specific lot in a publicly verifiable way.
Identity testing for a synthetic peptide relies on several complementary methods. Reversed-phase high-performance liquid chromatography separates the target from related impurities and reports purity as a percentage of total peak area. Mass spectrometry confirms molecular mass and can reveal deletions or truncations. Amino acid analysis and peptide mapping provide sequence-level confirmation, while counter-ion content and residual solvents are measured separately. A purity figure alone does not establish identity, so a complete dataset combines chromatographic and spectrometric evidence.
| 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 |
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.
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.
Solid peptide kept dry at minus twenty degrees Celsius, shielded from light and moisture, is generally considered stable for extended periods. Solutions are divided into single-use aliquots and held at minus twenty or minus eighty degrees Celsius, because repeated freeze-thaw cycles promote aggregation and loss of material to container surfaces. Hydrolysis of the backbone and oxidation of tryptophan are the principal degradation routes in aqueous solution, and both accelerate at ambient temperature. Hygroscopic uptake after a vial is opened can also shift the actual mass weighed, which affects any concentration calculated from it.
Routine characterisation relies on reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, using a C18 column and a water-acetonitrile gradient containing trifluoroacetic acid. Electrospray ionisation mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidised by-products that co-elute poorly. Sequence and stereochemistry require additional work, such as peptide mapping or amino acid analysis, because a chromatographic purity figure alone does not distinguish a diastereomer from the target peptide. Independent testing of research-grade material frequently shows measured content below the stated label, so a certificate of analysis is best read together with the method that produced it.
Forty-six Israeli civilians, 28 soldiers and one security officer were killed in Hezbollah's attacks on Israel. An additional three soldiers were killed in non-combat incidents; one by malfunctioning ammunition and the other two in a tank accident. Forty-seven soldiers, including a civilian researcher posthumously recognized as a soldier, were killed during combat in southern Lebanon. Hezbollah's attacks resulted in the evacuation of over 90,000 people—60,000 forced and 30,000 voluntary—from northern Israel. As of July 2024, the Israeli government issued orders for the evacuation of 43 settlements located within 3 miles (4.8 km) of the border with Lebanon. At least eight Israeli UAVs were shot down over Lebanon: four Hermes 450 and four Hermes 900 models. According to the Israeli Army Radio, 2,874 buildings have been reported damaged by Hezbollah, including 841 in need of rebuilding. Property damage was estimated to be around ₪1 billion (US$273 million). As of November 2024, over 60% of the buildings in Metula were destroyed by Hezbollah attacks since the start of the conflict. Three-fourths of the buildings in Manara, 382 buildings in Kiryat Shmona, and 55,000 acres of nature in northern Israel and the Golan Heights have been damaged or destroyed by Hezbollah's attacks, while major damage also took place in Nahariya and Shlomi.
==== Rare-earth mining ==== Due to natural occurrence of radioactive elements such as thorium and radium in rare-earth ore, mining operations also result in production of waste and mineral deposits that are slightly radioactive.
The form of government is a democratic federative republic, with a presidential system, as decided in a 1993 referendum. The president is both head of state and head of government of the Union and is elected for a four-year term, with the possibility of re-election for a second successive term. The current president is Luiz Inácio Lula da Silva. The president appoints the Ministers of State, who form the cabinet and assist in government.
Radicalized by recent events, Polish reformers (whether in exile or still resident in the reduced area remaining to the Commonwealth) were soon working on preparations for a national insurrection. Tadeusz Kościuszko, a popular general and a veteran of the American Revolution, was chosen as its leader. He returned from abroad and issued Kościuszko's proclamation in Kraków on March 24, 1794. It called for a national uprising under his supreme command. Kościuszko emancipated many peasants in order to enroll them as kosynierzy in his army, but the hard-fought insurrection, despite widespread national support, proved incapable of generating the foreign assistance necessary for its success. In the end, it was suppressed by the combined forces of Russia and Prussia, with Warsaw captured in November 1794 in the aftermath of the Battle of Praga.
Sources: en.wikipedia.org
Metabolic. The thyroid hormones increase the basal metabolic rate and have effects on almost all body tissues. Appetite, the absorption of substances, and gut motility are all influenced by thyroid hormones. They increase the absorption in the gut, generation, uptake by cells, and breakdown of glucose. They stimulate the breakdown of fats, and increase the number of free fatty acids. Despite increasing free fatty acids, thyroid hormones decrease cholesterol levels, perhaps by increasing the rate of secretion of cholesterol in bile. Cardiovascular. The hormones increase the rate and strength of the heartbeat. They increase the rate of breathing, intake and consumption of oxygen, and increase the activity of mitochondria. Combined, these factors increase blood flow and the body's temperature. Developmental. Thyroid hormones are important for normal development. They increase the growth rate of young people, and cells of the developing brain are a major target for the thyroid hormones T3 and T4. Thyroid hormones play a particularly crucial role in brain maturation during fetal development and first few years of postnatal life Other. The thyroid hormones also play a role in maintaining normal sexual function, sleep, and thought patterns. Increased levels are associated with increased speed of thought generation but decreased focus. Sexual function, including libido and the maintenance of a normal menstrual cycle, are influenced by thyroid hormones. After secretion, only a very small proportion of the thyroid hormones travel freely in the blood.
Most taste buds on the tongue and other regions of the mouth can detect umami taste, irrespective of their location. (The tongue map in which different tastes are distributed in different regions of the tongue is a common misconception.) Biochemical studies have identified the taste receptors responsible for the sense of umami as modified forms of mGluR4, mGluR1, and taste receptor type 1 (TAS1R1 + TAS1R3), all of which have been found in all regions of the tongue bearing taste buds. These receptors are also found in some regions of the duodenum. A 2009 review corroborated the acceptance of these receptors, stating, "Recent molecular biological studies have now identified strong candidates for umami receptors, including the heterodimer TAS1R1/TAS1R3, and truncated type 1 and 4 metabotropic glutamate receptors missing most of the N-terminal extracellular domain (taste-mGluR4 and truncated-mGluR1) and brain-mGluR4." Receptors mGluR1 and mGluR4 are specific to glutamate whereas TAS1R1 and TAS1R3 are responsible for the synergism already described by Akira Kuninaka in 1957. However, as of this date, the specific role of each type of receptor in taste bud cells remained unclear. All three receptors work together to produce the taste sensation.
Guinness Draught, the standard draught beer sold in kegs (but exist also a texture-like version in widget cans and bottles): 4.1 to 4.3% alcohol by volume (ABV); the Extra Cold is served through a super cooler at 3.5 °C (38.3 °F). Guinness Original/Extra Stout: 4.2 or 4.3% ABV in Ireland and the United Kingdom, 4.1% in Germany, 5.0% in continental Europe and Scandinavia (such as Sweden), 4.8% in Namibia and South Africa, 5.6% in the United States and Canada, and 6% in Australia and Japan. Guinness Foreign Extra Stout: 7.5% ABV version sold in Europe, Africa, the Caribbean, Asia, and the United States. The basis is an unfermented but hopped Guinness wort extract shipped from Dublin, which is added to local ingredients and fermented locally. The strength can vary, for example, it is sold at 5% ABV in China, 6.5% ABV in Jamaica and East Africa, 6.8% in Malaysia, 7.5% in the United States, and 8% ABV in Singapore. In Nigeria a proportion of sorghum is used. Foreign Extra Stout is blended with a small amount of intentionally soured beer. Formerly, it was blended with beer that soured naturally as a result of fermenting in ancient oak tuns with a Brettanomyces population; it is now made with pasteurised beer that has been soured bacterially. It was previously known as West Indies Porter, then Extra Stout and finally Foreign Extra Stout. It was first made available in the UK in 1990. Guinness Special Export Stout, Commissioned by John Martin of Belgium in 1912. The first variety of Guinness to be pasteurised, in 1930. 8% ABV.
=== 2009-2013: Lineup changes, Teške Boje === By the end of 2009, Kilmister, Domaćinović, Tibljaš and Blažević left the band due to personal differences with Bare. This left Bare as the only remaining original member of Majke. He and Čalić assembled a new lineup consisting of bassist Mario Rašić, who previously played with Bare in his backing band Plaćenici; Gatuzo guitarist Damir Trkulja - Šiljo, drummer Damir Šomen and keyboardist Viktor Lipić. This lineup recorded the band's sixth studio album, "Teške Boje", which was released in 2011. On this album, the band displayed a much darker and more aggressive style of blues rock, with psychedelic elements mixed in as well. The title track was a hit, with some critics even calling it the "best Croatian rock song of the last 20 years", and a music video was filmed for it. Other staples from the album included "Pozovi Me U Noć" and "Depresija". In 2012, the album won several Porin awards for song of the year, best rock album, and best music video of the year. Soon afterwards, Šiljo left the band due to personal differences with Bare and was replaced by ex-Pips, Chips i Videoclips guitarist Alen Kraljić, who also played with Bare as a member of Plaćenici. In 2013, the band released the live album "Majke U Tvornici", which was recorded six years ago at the Tvornica Kulture venue. By the end of the year, Zoran Čalić left the band once again. He went on to form a new band called Zoran Čalić Bend.
Nevertheless, the resistance of extracellular matrix proteins to proteolysis renders their advanced glycation end products less conducive to being eliminated. While the AGE free adducts are released directly into the urine, AGE peptides are endocytosed by the epithelial cells of the proximal tubule and then degraded by the endolysosomal system to produce AGE amino acids. It is thought that these acids are then returned to the kidney's inside space, or lumen, for excretion. AGE free adducts are the major form through which AGEs are excreted in urine, with AGE-peptides occurring to a lesser extent but accumulating in the plasma of patients with chronic kidney failure. Larger, extracellularly derived AGE proteins cannot pass through the basement membrane of the renal corpuscle and must first be degraded into AGE peptides and AGE free adducts. Peripheral macrophage as well as liver sinusoidal endothelial cells and Kupffer cells have been implicated in this process, although the real-life involvement of the liver has been disputed.
Sources: en.wikipedia.org
In broad terms, spent nuclear fuel has three main components. The first consists of fission products, the leftover fragments of fuel atoms after they have been split to release energy. Fission products come in dozens of elements and hundreds of isotopes, all of them lighter than uranium. The second main component of spent fuel is transuranics (atoms heavier than uranium), which are generated from uranium or heavier atoms in the fuel when they absorb neutrons but do not undergo fission. The actinide series on the periodic table runs from actinium to lawrencium and includes uranium as well as transuranic elements. The third and largest component is the remaining uranium which is around 98.25% uranium-238, 1.1% uranium-235, and 0.65% uranium-236. The U-236 comes from the non-fission capture reaction where U-235 absorbs a neutron but releases only a high energy gamma ray instead of undergoing fission. The physical behavior of the fission products is markedly different from that of the actinides. In particular, fission products do not undergo fission and therefore cannot be used as nuclear fuel. Indeed, because fission products are often neutron poisons (absorbing neutrons that could be used to sustain a chain reaction), fission products are viewed as nuclear 'ashes' left over from consuming fissile materials. Furthermore, only seven long-lived fission product isotopes have half-lives longer than a hundred years, which makes their geological storage or disposal less problematic than for transuranic materials.
== History == Secukinumab was discovered and developed by Novartis using developmental name AIN457, and the first publication was a Phase I trial published in 2010. In January 2015, secukinumab was approved in the United States and in the European Union to treat adults with moderate-to-severe plaque psoriasis. It is the first IL17A inhibiting drug ever approved. In January 2016, the FDA approved it to treat adults with ankylosing spondylitis, and psoriatic arthritis and in February 2018, a label update was approved to include the treatment for moderate-to-severe scalp psoriasis.
Hospital pharmacists and trained pharmacy technicians compound sterile products for patients including total parenteral nutrition (TPN), and other medications are given intravenously. That is a complex process that requires adequate training of personnel, quality assurance of products, and adequate facilities. Several hospital pharmacies have decided to outsource high-risk preparations and some other compounding functions to companies who specialize in compounding. The high cost of medications and drug-related technology and the potential impact of medications and pharmacy services on patient-care outcomes and patient safety require hospital pharmacies to perform at the highest level possible.
Using cells in culture Pre-treating cells in a hypotonic solution, which swells them and spreads the chromosomes Arresting mitosis in metaphase by a solution of colchicine Squashing the preparation on the slide forcing the chromosomes into a single plane Cutting up a photomicrograph and arranging the result into an indisputable karyogram. It took until 1956 for it to be generally accepted that the karyotype of man included only 46 chromosomes. The great apes have 48 chromosomes. Human chromosome 2 was formed by a merger of ancestral chromosomes, reducing the number.
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.
Dry powder is usually held frozen, shielded from light, and kept away from moisture. Desiccant packaging limits hydrolysis during storage. Solutions are typically aliquoted and frozen once, because repeated thawing shortens useful life.