The short version of MC1R fits in a sentence. The long version — which is the one that helps — is below.
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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.
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 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.
| 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 |
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.
The peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
Melanotan-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
Melanotan II is a synthetic peptide analog modeled on alpha-melanocyte-stimulating hormone, a naturally occurring signaling peptide involved in pigmentation. Its structure is a cyclic heptapeptide containing two non-natural substitutions, norleucine at position four and D-phenylalanine at position seven. These modifications resist enzymatic breakdown and extend the molecule's activity relative to the native hormone. The compound binds melanocortin receptors and is studied mainly as a pharmacological tool rather than a therapeutic product. It has never received approval as a medicine in any major jurisdiction.
The compound was developed in the late 1980s and 1990s by academic researchers investigating photoprotection. The rationale held that stimulating melanin production might reduce ultraviolet damage to skin and lower skin cancer risk. Early work examined receptor binding, pigment response, and short-term tolerability in small studies. That program did not produce an approved drug, and formal development stalled after early-phase trials. Whether induced pigmentation confers meaningful photoprotection remains an open question.
Heseltine resigned as managing director of Haymarket on his promotion to principal opposition spokesman on transport in 1969, although he continued as chairman of the board until he became a minister in 1970, at which point he resigned from the board altogether, whilst remaining a major shareholder.
=== Behavior === The primary non-cellular functions of tau is to negatively regulate long-term memory and to facilitate habituation (a form of non-associative learning), two higher and more integrated physiological functions. Since regulation of tau is critical for memory, this could explain the linkage between tauopathies and cognitive impairment. In mice, while the reported tau knockout strains present without overt phenotype when young, when aged, they show some muscle weakness, hyperactivity, and impaired fear conditioning. However, neither spatial learning in mice, nor short-term memory (learning) in Drosophila seems to be affected by the absence of tau. In addition, tau knockout mice have abnormal sleep-wake cycle, with increased wakefulness periods and decreased non-rapid eye movements (NREM) sleep time.
Presidential elections were held in the United States on November 5, 2024. The Republican ticket of former president Donald Trump and Ohio junior senator JD Vance defeated the Democratic ticket of incumbent vice president Kamala Harris and Minnesota governor Tim Walz. The incumbent president, Joe Biden of the Democratic Party, initially ran for re-election, easily sweeping aside a challenge from Democratic representative Dean Phillips of Minnesota in the Democratic primaries to become the party's presumptive nominee. However, what was broadly considered a poor debate performance in June 2024 intensified concerns about his age and health, and led to calls within his party for him to leave the race. After initially declining to do so, Biden ultimately withdrew from the race on July 21, 2024, becoming the first eligible incumbent president to run but subsequently withdraw since Lyndon B. Johnson in 1968. Biden immediately endorsed Harris, who officially became the party's presidential nominee on August 5 and the first presidential nominee who did not participate in the primaries since Vice President Hubert Humphrey in 1968. Harris selected Walz as her running mate. Trump, who lost the 2020 presidential election to Biden, ran for reelection to a nonconsecutive second term. Trump became the presumptive Republican Party's presidential nominee on March 12, 2024, easily defeating challengers such as former South Carolina governor Nikki Haley and Florida governor Ron DeSantis in the Republican primaries. He was shot in the ear in an assassination attempt on July 13, 2024.
=== EC 1.2.2 With a cytochrome as acceptor === EC 1.2.2.1: formate dehydrogenase (cytochrome) EC 1.2.2.2: Now covered by EC 1.2.5.1, pyruvate dehydrogenase (quinone) EC 1.2.2.3: Now EC 1.17.2.3, formate dehydrogenase (cytochrome-c-553) EC 1.2.2.4: Now classified as EC 1.2.5.3, aerobic carbon monoxide dehydrogenase
Sources: en.wikipedia.org
=== Antibacterial and potential immunosuppressive properties === Studies suggest that creatinine can be effective in killing bacteria of many species, both Gram positive and Gram negative, as well as diverse antibiotic-resistant bacterial strains. Creatinine appears not to affect the growth of fungi and yeasts; this can be used to isolate slower growing fungi free from the normal bacterial populations found in most environmental samples. The mechanism by which creatinine kills bacteria is not currently known. Some reports also suggest that creatinine may have immunosuppressive properties.
In the event of Palestine coming within the spheres of influence of Great Britain or France at the close of the war, the governments of those powers will not fail to take account of the historic interest that country possesses for the Jewish community. The Jewish population will be secured in the enjoyment of civil and religious liberty, equal political rights with the rest of the population, reasonable facilities for immigration and colonisation, and such municipal privileges in the towns and colonies inhabited by them as may be shown to be necessary. On 11 March, telegrams were sent in Grey's name to Britain's Russian and French ambassadors for transmission to Russian and French authorities, including the formula, as well as:
Although WHO recommends artemisinin-based remedies for treating uncomplicated malaria, resistance to the drug can no longer be ignored. Also in the 1970s Chinese researcher Zhang TingDong and colleagues investigated the potential use of the traditionally used substance arsenic trioxide to treat acute promyelocytic leukemia (APL). Building on his work, research both in China and the West eventually led to the development of the drug Trisenox, which was approved for leukemia treatment by the FDA in 2000. Huperzine A, an extract from the herb, Huperzia serrata, is under preliminary research as a possible therapeutic for Alzheimer's disease, but poor methodological quality of the research restricts conclusions about its effectiveness. Ephedrine in its natural form, known as má huáng (麻黄) in TCM, has been documented in China since the Han dynasty (206 BCE – 220 CE) as an antiasthmatic and stimulant. In 1885, the chemical synthesis of ephedrine was first accomplished by Japanese organic chemist Nagai Nagayoshi based on his research on Japanese and Chinese traditional herbal medicines Pien tze huang was first documented in the Ming dynasty.
The downregulation of ALAS1 lowers the levels of neurotoxic intermediates that cause AHP symptoms. Years of research have led to a greater understanding of siRNA therapies beyond those affecting the liver. As of 2019, Alnylam Pharmaceuticals was involved in therapies that may treat amyloidosis and CNS disorders like Huntington's disease and Alzheimer's disease. They have also partnered with Regeneron Pharmaceuticals to develop therapies for CNS, eye, and liver diseases. As of 2020, Onpattro and Givlaari were available for commercial application, and two siRNAs, lumasiran (ALN-GO1) and inclisiran, have been submitted for new drug application to the FDA. Several siRNAs are undergoing phase 3 clinical studies, and more candidates are in the early developmental stage. In 2020, Alnylam and Vir Pharmaceuticals announced a partnership and have started working on an RNAi therapy that would treat severe cases of COVID-19. Other companies that have had success in developing a pipeline of siRNA therapies include Dicerna Pharmaceuticals, partnered with Eli Lilly and Company, and Arrowhead Pharmaceuticals, partnered with Johnson and Johnson. Several other large pharmaceutical companies, such as Amgen and AstraZeneca, have also invested heavily in siRNA therapies, seeing potential success in this area of biological drugs.
His work has emphasized the use of gene expression profiling and genomic analysis to improve diagnostic accuracy and distinguish between histologically similar tumors, including synovial sarcoma and other spindle cell neoplasms. Nielsen's studies have also examined the role of characteristic fusion oncogenes, such as SS18–SSX in synovial sarcoma, and their effects on gene regulation and tumor development. This research has helped clarify the biological mechanisms underlying sarcoma progression and supported the development of molecularly defined disease categories.
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.
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.