Everything below concerns cyclic heptapeptide. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-07-27. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Outside regulated medicine, melanotan II circulates through online vendors as a research chemical, often marketed for tanning. Products sold this way vary widely in purity, concentration, and labeling accuracy, and independent testing has documented discrepancies. Published reports describe both pigment effects and adverse reactions, including nausea, flushing, and darkening of existing moles. Long-term safety data are sparse, and no large controlled trial has established a risk profile. Questions about cumulative effects on melanocytes remain unresolved in the literature.
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.
Melanotan-2 is a synthetic linear peptide built from seven amino acids arranged in a short chain. Its sequence is commonly written as Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH2, which includes a modified N-terminus and an amidated C-terminus. The molecule belongs to the melanocortin family and acts as a receptor agonist. Structural features such as the D-phenylalanine residue and the Nle substitution are associated with increased stability against enzymatic degradation relative to the natural parent peptide.
The compound emerged from research programs in the 1980s that examined analogues of alpha-melanocyte-stimulating hormone for pigmentation and photoprotection. Investigators modified the native sequence to extend activity duration and potency. A related analogue, afamelanotide, was developed within the same broad line of inquiry and eventually gained approval in certain jurisdictions for a rare light-sensitivity condition. Melanotan-2 itself did not progress through the same regulatory route and has no approved therapeutic indication.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Belongs to the melanocortin agonist family |
| Key substitutions | Nle4 and D-Phe7 | Improve resistance to enzymatic degradation |
| Molecular formula | C50H69N15O9 | Approximately 1024 g/mol |
| Regulatory status | Not approved as a medicine | Distributed as a research chemical |
| Common synonyms | Melanotan II, MT-II, MT-2 | Spelling varies across sources |
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.
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
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.
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.
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-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.
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.
Narrated by Robin Ellis, produced by Rachel Allen, directed by Sarah Marris, made by TVF Media 24 May Storm in a D Cup, about breast implants; Sally Kirkland was a main protagonist against implants; Sybil Niden Goldrich of the Command Trust Network; Marcia Angell of The New England Journal of Medicine; the British 1990s glamour model Teresa May; Roger Sturrock of the University of Glasgow; Dennis Deapen of the University of Southern California; Sai Ramastry of the University of Illinois Chicago; British 1990s glamour model Hannah Callow sat nonchalantly on a London underground train, with surreptitious nearby male attention. Directed by Martin Durkin (often chose quite controversial topics), made by his company Kugelblitz 7 June Curse of the Phantom Limbs, about sensations of phantom limbs; Jackie Naylor lost her hand in an accident on the A57 in 1989; neuroscientist Peter Halligan, since 2018 the Chief Scientific Adviser for Wales; photographer Alexa Wright makes superfiction images of phantom limbs; the Douglas Bader Centre at the Queen Mary's Hospital, Roehampton; Canadian psychologist Ronald Melzack of McGill University; Conrad Weiskrantz, son of neuroscientist Lawrence Weiskrantz had a motorbike accident on a country road, where he hit a vehicle towing a trailer turning right; the Silver Spring monkeys; neuroscientist V. S. Ramachandran of University of California, San Diego; Canadian neurosurgeon Wilder Penfield conducted cortical stimulation mapping research in the 1950s, resulting in the cortical homunculus and cortical maps; neurosurgeon Tipu Aziz.
=== Human clinical studies === In human clinical studies, epitalon and epithalamin both significantly increased telomere lengths in the blood cells of patients of ages 60-65 and 75-80, and their efficacy was comparable to one another. Epitalon and epithalamin appear to restore melatonin secretion by the pineal gland in both aged monkeys and humans. A human clinical trial conducted on a sample of retinitis pigmentosa patients found that epitalon produced a positive clinical effect in 90% of cases in the treated group. In another human clinical trial conducted on a sample of pulmonary tuberculosis patients, epitalon did not appear to correct pre-existing structural aberrations of chromosomes associated with telomere degradation, but did appear to exert a protective effect against the future development of additional chromosomal aberrations. A human prospective cohort study conducted on a sample of 266 people over age 60 demonstrated that treatment with epithalamin, the pineal gland extract upon which epitalon is based, produced a 1.6–1.8-fold reduction in mortality during the following 6 years, a 2.5-fold reduction in mortality when combined with thymalin, and a 4.1-fold reduction in mortality when combined with thymalin and administered annually instead of only once at study onset.
Research on vitamin C in the common cold has been divided into effects on prevention, duration, and severity. Oral intakes of more than 200 mg/day taken on a regular basis was not effective in prevention of the common cold. Restricting analysis to trials that used at least 1000 mg/day also saw no prevention benefit. However, taking a vitamin C supplement on a regular basis did reduce the average duration of the illness by 8% in adults and 14% in children, and also reduced the severity of colds. Vitamin C taken on a regular basis reduced the duration of severe symptoms but had no effect on the duration of mild symptoms. Therapeutic use, meaning that the vitamin was not started unless people started to feel the beginnings of a cold, had no effect on the duration or severity of the illness. Vitamin C distributes readily in high concentrations into immune cells, promotes natural killer cell activities, promotes lymphocyte proliferation, and is depleted quickly during infections, effects suggesting a prominent role in immune system function. The European Food Safety Authority concluded there is a cause and effect relationship between the dietary intake of vitamin C and functioning of a normal immune system in adults and in children under three years of age.
Sources: en.wikipedia.org
In rearranging Italy's political geography, Octavian Augustus merged Calabria and Basilicata into Regio III Lucania et Bruttii, with the capital and seat of the corrector in Reggio, the region's largest city.
On 18 January, ambassadors from all 27 member states of the EU held an emergency meeting on Trump's threats. After Trump reversed his decision on implementing tariffs, EU officials were sceptical, but announced on 22 January that approval of the trade agreement would resume.
=== Role in muscle regeneration === The first step to understanding the importance of macrophages in muscle repair, growth, and regeneration is that there are two "waves" of macrophages with the onset of damageable muscle use– subpopulations that do and do not directly have an influence on repairing muscle. The initial wave is a phagocytic population that comes along during periods of increased muscle use that are sufficient to cause muscle membrane lysis and membrane inflammation, which can enter and degrade the contents of injured muscle fibers. These early-invading, phagocytic macrophages reach their highest concentration about 24 hours following the onset of some form of muscle cell injury or reloading. Their concentration rapidly declines after 48 hours. The second group is the non-phagocytic types that are distributed near regenerative fibers. These peak between two and four days and remain elevated for several days while muscle tissue is rebuilding. The first subpopulation has no direct benefit to repairing muscle, while the second non-phagocytic group does. It is thought that macrophages release soluble substances that influence the proliferation, differentiation, growth, repair, and regeneration of muscle, but at this time the factor that is produced to mediate these effects is unknown. It is known that macrophages' involvement in promoting tissue repair is not muscle specific; they accumulate in numerous tissues during the healing process phase following injury.
Sources: en.wikipedia.org
An antibody elution is a clinical laboratory diagnostic procedure which removes sensitized antibodies from red blood cells, in order to determine the blood group system antigen the antibody targets. An antibody elution is deemed necessary when antibodies of the immunoglobulin class G (IgG) are found sensitized (bound) to peripheral red cells collected from a blood product transfusion recipient. IgG antibodies are detected using an assay known as the direct antiglobulin test. Antibody elutions are specialized tests used in clinical blood banks. Examples of routine tests include ABO/Rh, antibody screen, antibody identification, and antiglobulin testing. Examples of other specialized tests used in blood banking include: treatment with thiol reagent, monocyte monolayer assay, enzyme treatment, and adsorptions. This procedure aids in the investigation of antibodies that are difficult to identify, distinguishing transfusion reactions, hemolytic disease of the fetus and newborn, and warm autoantibody workups.
Cyclohexane is converted at 70 °C with nitrogen dioxide/air into a mixture of nitrocyclohexane (70%), cyclohexyl nitrate (7%) and cyclohexanol (5%). N-hydroxyphthalimide serves as an oxidizing agent in photographic developers and as charge control agents in toners have been described in the patent literature.
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Sources: en.wikipedia.org
It is a synthetic cyclic peptide designed as an analog of alpha-melanocyte-stimulating hormone. It acts on melanocortin receptors and is best known from research into pigmentation. It is not an approved pharmaceutical product.
No regulatory agency has approved it for any indication. It is encountered as a research chemical sold outside pharmaceutical supply chains. Products marketed this way are not subject to the manufacturing and labeling requirements that apply to approved drugs.
Reports describe increased skin pigmentation as well as side effects such as nausea, flushing, and changes to existing moles. Much of the evidence comes from small studies and case reports rather than large trials. The long-term safety profile is therefore uncertain.
No. Melanotan-2 is manufactured synthetically. The naturally occurring peptide in the same family is alpha-melanocyte-stimulating hormone, which the body produces as part of normal endocrine and neural signalling.