melanocortin receptors 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 2025-11-17. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, the naturally occurring peptide involved in pigmentation signalling. Its sequence is conventionally written as Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, with a lactam bridge joining the aspartate side chain to the lysine side chain. The empirical formula is C50H69N15O9 and the monoisotopic mass lies near 1023.5 daltons. N-terminal acetylation and the D-configured phenylalanine both increase resistance to enzymatic breakdown compared with the parent hormone.
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.
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.
Melanotan-2 is handled in the laboratory as a lyophilised powder that dissolves readily in water, dimethyl sulfoxide and dimethylformamide, with limited solubility in ethanol. Stock solutions prepared in an organic solvent often precipitate when diluted into aqueous buffer, so gradual dilution with mixing is standard practice. The peptide carries a tryptophan residue and a histidine residue, both sensitive to oxidation and to alkaline conditions. Working solutions are therefore kept near neutral to slightly acidic pH, protected from light, and consumed within the same working session whenever that is practical.
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.
| 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 |
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.
Melanotan-2 appears on the World Anti-Doping Agency prohibited list within the peptide hormone class, and several national regulators treat it as an unapproved prescription substance. Some countries restrict importation or sale for personal use. Because the compound is widely traded as a research chemical, the practical legal picture differs between jurisdictions and shifts over time. Human safety data covering long periods are limited, and whether repeated pigmentation changes carry any lasting risk to melanocytes remains an open question.
Freeze-dried melanotan-2 is normally kept as a desiccated powder at minus twenty degrees Celsius or lower, shielded from light and moisture. Peptides of this size degrade through hydrolysis, oxidation and deamidation, and each pathway accelerates as temperature and water activity rise. Repeated freeze-thaw cycles promote aggregation and loss of material, so aliquoting a stock solution before freezing is standard laboratory practice. Once dissolved, the solution is markedly less stable than the powder. In laboratory work, solutions are generally refrigerated and used within days rather than kept for months.
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.
Melanotan II holds no marketing authorisation from the Food and Drug Administration, the European Medicines Agency, the UK Medicines and Healthcare products Regulatory Agency or Australia's Therapeutic Goods Administration. Products sold under that name are treated as unapproved new drugs, and their sale or import is prohibited in several jurisdictions. Other countries classify the peptide as a prescription-only medicine or place it among controlled substances, so the legal position changes with the destination market. No pharmacopoeial monograph supplies an official specification, because the material is not a licensed pharmaceutical. Consequently, products offered online are not manufactured to a shared public standard.
The peer-reviewed record is dominated by small early-phase studies, case reports and pharmacovigilance summaries rather than large randomised trials. Papers typically examine tanning response, receptor selectivity or patterns of reported adverse events. Many note that participants obtained the peptide outside a clinical setting, which limits verification of composition and administered amount. Reported events vary widely, and causality is frequently unclear because the identity and purity of self-sourced material are unknown. Open questions include whether repeated melanocortin receptor stimulation produces cumulative effects, and how often label claims match actual content.
=== Liquid chromatography-mass spectrometry === Liquid chromatography-mass spectrometry (LC-MS) has the capability to analyze compounds that are polar and less volatile. Derivatization is not required for these analytes as it would be in GC-MS, which simplifies sample preparation. As an alternative to immunoassay screening which generally requires confirmation with another technique, LC-MS offers greater selectivity and sensitivity. This subsequently reduces the possibility of a false negative result that has been recorded in immunoassay drug screening with synthetic cathinones and cannabinoids. A disadvantage of LC-MS on comparison to other analytical techniques such as GC-MS, is the high instrumentation cost. However, recent advances in LC-MS have led to higher resolution and sensitivity which assists in the evaluation of spectra to identify forensic analytes.
The Sunni Mamluk campaigns led to the destruction of many Christian churches and monasteries and Druze sanctuaries khilwat, and caused mass destruction of Maronite and Druze villages and the killings and mass displacement of its inhabitants. In the 12th century Kisrawan had a tribal and religiously mixed population of Maronite Christians, Twelver Shia Muslims, Alawites and Druze. Information about the Christians of the Kisrawan before the 12th century is scant, though in the 9th century there was evidently an organized Christian, likely Maronite, community governed by village headmen. Under Muslim rule, Christians were mandated to pay the jizya, a form of poll tax, though its actual collection in Mount Lebanon was likely done on an inconsistent basis. The Druze religion, which branched off of Isma'ili Shia Islam in the early 11th century, and separated later from both Isma'ilism and Islam altogether, gained adherents among people in Mount Lebanon and its environs, including much of the Tanukh settlers in the hills east of Beirut. Certain aspects of the faith, such as transmigration of souls between adherents and incarnation, were viewed as heretical or kufr (infidelity) and foreign by Sunni and Shia Muslims, but contributed to solidarity among the Druze, who closed their religion to new converts in 1046 due to the threat of persecution.
In the 1970s, Judi Sheppard Missett helped create the market for commercial aerobics with her Jazzercise program, at the same time as Jacki Sorensen was expanding her system of aerobic dancing. In the 1980s, Richard Simmons hosted an aerobic exercise show on television, and followed Jane Fonda's lead by releasing a series of exercise videos. In the 1990s, Billy Blanks's Tae Bo helped popularize cardio-boxing workouts that incorporated martial arts movements. Reebok shoes popularized step aerobics with their Reebok Step device and training program.
== MTRR gene == The Methionine Synthase Reductase (MTRR) gene primarily acts in the reductive regeneration of cob(I)alamin (vitamin B12). Cob(I)alamin is a cofactor that maintains activation of the methionine synthase enzyme (MTR) methionine synthase, linking folate and methionine metabolism. Donation of methyl groups from folate are utilized for cellular and DNA methylation, influencing epigenetic inheritance.
The final push for independence of Poland took place on the ground in October–November 1918. Near the end of the war, Austro-Hungarian and German units were being disarmed, and the Austrian army's collapse freed Cieszyn and Kraków at the end of October. Lviv was then contested in the Polish–Ukrainian War of 1918–1919. Ignacy Daszyński headed the first short-lived independent Polish government in Lublin from 7 November, the leftist Provisional People's Government of the Republic of Poland, proclaimed as a democracy. Germany, now defeated, was forced by the Allies to stand down its large military forces in Poland. Overtaken by the German Revolution of 1918–1919 at home, the Germans released Piłsudski from prison. He arrived in Warsaw on 10 November and was granted extensive authority by the Regency Council; Piłsudski's authority was also recognized by the Lublin government.[b1] On 22 November, he became the temporary head of state. Piłsudski was held by many in high regard, but was resented by the right-wing National Democrats. The emerging Polish state was internally divided, heavily war-damaged and economically dysfunctional.
Sources: en.wikipedia.org
=== Propagation === While they can be successfully propagated in early spring, epimediums are best divided in late summer, with the aim of promoting rapid re-growth of roots and shoots before the onset of winter. Several breeders (in particular Darrell Diano Probst, Tim Branney & Robin White) have also undertaken their own hybridization programmes with the genus. Various new nursery selections are gradually appearing in the horticulture trade, the best of which extend the colour and shape range of the flowers available to the gardener.
Oxaloacetic acid + Glutamate ⇌ α-Ketoglutarate + Aspartate (catalyzed by aspartate aminotransferase) When skeletal muscle is at rest (ADP<ATP), the aspartate is no longer needed for the purine nucleotide cycle and can therefore be used with α-ketoglutarate to produce glutamate and oxaloacetic acid (the above reaction reversed).α-Ketoglutarate + Aspartate ⇌ Oxaloacetic acid + Glutamate (catalyzed by aspartate aminotransferase)
== Broadcast == Matlock premiered with a sneak peek on September 22, 2024, before its timeslot premiere on October 17 on CBS. In Canada, the series airs on Global and is available to stream on StackTV. The second season premiered on October 12, 2025. In Australia, the show premiered on Channel Ten on the November 11, 2024 and has continued to air its second season through January 2026 and also airs on Paramount+. In Croatia, the show premiered on national HRT 1 starting with the first season on the 15th. June 2026.
== Gingival fibers and periodontitis == In theory, gingival fibers are the protectors against periodontitis, as once they are breached, they cannot be regenerated. When destroyed, the gingival sulcus (labelled G in the diagram) increases in depth apically, allowing more debris and bacteria to remain in intimate contact with the delicate sulcular and junctional epithelia for longer times.
Sources: en.wikipedia.org
Cottage cheese is a type of fresh cheese with a mild flavor and a creamy, heterogeneous texture made from skimmed milk – hence the low milkfat content. It is made by adding an acid – like vinegar or lemon juice – to the milk which causes the milk proteins (curds) to separate from the liquid (whey). The curds are then drained and mixed with cream and salt, giving cottage cheese its slightly tangy taste and creamy texture. The addition of a "dressing" to the curd grains is primarily responsible for the taste of the finished food. Cottage cheese is not aged. It was first called 'cottage cheese' in 1831, likely originating from Pennsylvania Dutch immigrants making cheese curds to spread on snacks in their homesteads (cottages). Cottage cheese can be relatively low in milkfat and calories for the high amount of protein it provides, and is a rich source of vitamin B12. Cottage cheese comes in different fat levels, including low–fat and fat–free – but even an original 'full fat' version has fewer calories than a chunk of hard cheese or wedge of soft cheese. Cottage cheese is a versatile nutritious food readily added to fruit, vegetables, bread and breakfast items, pastas, sauces, and desserts.
== Treatment == The most important measure is prevention – avoidance of the drugs and foods that cause hemolysis. Vaccination against some common pathogens (e.g. hepatitis A and hepatitis B) may prevent infection-induced attacks. In the acute phase of hemolysis, blood transfusions might be necessary, or even dialysis in acute kidney failure. Blood transfusion is an important symptomatic measure, as the transfused red cells are generally not G6PD deficient and will live a normal lifespan in the recipient's circulation. Those affected should avoid drugs such as aspirin. Some patients may benefit from the removal of the spleen (splenectomy), as this is an important site of red cell destruction. Folic acid should be used in any disorder featuring a high red cell turnover. Although vitamin E and selenium have antioxidant properties, their use does not decrease the severity of G6PD deficiency. AG1, a recently discovered small molecule, has been shown to increase the activity of the G6PD enzyme in the three common variants of the deficiency. Due to the absence of medications to treat G6PD, AG1 is a promising precursor in developing a pharmacological treatment effective for multiple G6PD enzymopathies.
Isoaspartic acid (isoaspartate, isoaspartyl, β-aspartate) is an aspartic acid residue isomeric to the typical α peptide linkage. It is a β-amino acid, with the side chain carboxyl moved to the backbone. Such a change is caused by a chemical reaction in which the nitrogen atom on the N+1 following peptide bond (in black at top right of Figure 1) nucleophilically attacks the γ-carbon of the side chain of an asparagine or aspartic acid residue, forming a succinimide intermediate (in red). Hydrolysis of the intermediate results in two products, either aspartic acid (in black at left) or isoaspartic acid, which is a β-amino acid (in green at bottom right). The reaction also results in the deamidation of the asparagine residue. Racemization may occur leading to the formation of D-aminoacids.
=== 21st century === Heather C. Allen, American chemist whose research focuses air-liquid interfaces Rommie Amaro, American chemist focusing on development of computational methods in biophysics for applications to drug discovery. Emily Balskus, American organic and biological chemist, and microbiologist. Recipient of the 2020 Alan T. Waterman Award for her work on understanding the chemistry of metabolic processes. Professor at Harvard University. Natalie Banerji, Swiss chemist and Professor of Chemistry at the University of Bern who studies organic and hybrid materials using ultrafast spectroscopies. Margaret Brimble, New Zealand chemist whose research has included investigations of shellfish toxins and means to treat brain injuries. Jane P. Chang, chemical engineer, materials scientist and professor at UCLA known for her research developing advanced atomic layer deposition (ALD) and etching techniques with applications in microelectronics and energy storage devices. Sherry Chemler, American Organic Chemist. Professor University at Buffalo. ACS Cope Scholar Award recipient (2017). Paulette Clancy, British chemist focusing on computational and machine learning methods, particularly chemistry-informed Bayesian optimization, to model the behavior of semiconductor materials. Sheila Hobbs DeWitt, American chemist. Chair, President, CEO, Cofounder of DeuteRx which has developed PXL065 a Deuterated drug. ACS Kathryn C. Hach Award for Entrepreneurial Success (2025). She is a pioneer of Combinatorial Chemistry.
1. "Unichem, Optimus enter into strategic tie-up”. The Hindu Business Line.com. Published on 5 November 2018. 2. “Unichem to acquire 20% stake in Optimus group for Rs 120 cr”. Business-standard.com. Published on 5 November 2018. 3. “Unichem Labs gets USFDA nod for asthma drug”. Economictimes.com. Published on 4-July-2018. 4. “Unichem Labs' Ghaziabad unit gets EIR from USFDA” Thebusinessline.com. Published on 5 June 2018. 2018. 5. “Unichem Laboratories Gets ANDA Approval from U.S. FDA for Valsartan Tablets, USP.” Reuters.com. Published on 7 May 2018. 6. “How Torrent Pharma is integrating Unichem to boost its domestic business.” Business-standard.com. Published on 13 February 2018. 7. “Torrent Pharma completes acquisition of Unichem Laboratories Ltd.” Economictimes.com. Published on 14 December 2017. 8. “This conventional businessman is set for second innings”. Economictimes.indiatimes.com. Published on 4 November 2017. 9. “Unichem Labs gets EIR from USFDA for Goa facility” Economics times.com. Published on 30 June 2017. 10. "Unichem Lab appoints Mr. Bhagwat S. Dhingra as Chief Executive-Domestic Pharma". Moneycontrol.com. 13 August 2012. 11. "Contact Pharmaceutical Company India - Unichem Laboratories". Unichemlabs.com. Retrieved 3 October 2010. 12. "Interview of Dr P A Mody, CEO, Unichem Laboratories Ltd". Indiainfoline.com. Retrieved 3 October 2010. 13. "BSE Plus". Bseindia.com. Retrieved 3 October 2010. 14. "Pharmaceutical Business, Pharma Business Development - Unichem Laboratories". Unichemlabs.com. Retrieved 3 October 2010. 15.
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.
Purity is normally stated as an area percentage from high-performance liquid chromatography, for example ninety-five or ninety-eight percent. That figure describes the proportion of ultraviolet-absorbing material eluting as the main peak. It says nothing about water content, counterions, residual solvents or mass fraction of the peptide itself.