cyclic heptapeptide 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 2025-10-22. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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 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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms add to total mass |
| Molecular mass | About 1024 daltons | Calculated for the free base |
| Structural class | Cyclic heptapeptide | Contains D-phenylalanine and norleucine |
| Parent hormone | Alpha-melanocyte-stimulating hormone | Endogenous tridecapeptide of 13 residues |
| Receptor profile | Non-selective melanocortin agonist | Interacts with MC1R, MC3R, MC4R and MC5R |
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.
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.
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.
== Mechanism == Myelofibrosis is a clonal neoplastic disorder of hematopoiesis, the formation of blood cellular components. It is one of the myeloproliferative disorders, diseases of the bone marrow in which excess cells are produced at some stage. Production of cytokines such as fibroblast growth factor by the abnormal hematopoietic cell clone (particularly by megakaryocytes) leads to replacement of the hematopoietic tissue of the bone marrow by connective tissue via collagen fibrosis. The decrease in hematopoietic tissue impairs the patient's ability to generate new blood cells, resulting in progressive pancytopenia, a shortage of all blood cell types. However, the proliferation of fibroblasts and deposition of collagen is a secondary phenomenon, and the fibroblasts themselves are not part of the abnormal cell clone. In primary myelofibrosis, progressive scarring, or fibrosis, of the bone marrow occurs, for the reasons outlined above. The result is extramedullary hematopoiesis, i.e. blood cell formation occurring in sites other than the bone marrow, as the hemopoietic cells are forced to migrate to other areas, particularly the liver and spleen. This causes an enlargement of these organs. In the liver, the abnormal size is called hepatomegaly. Enlargement of the spleen is called splenomegaly, which also contributes to causing pancytopenia, particularly thrombocytopenia and anemia. Another complication of extramedullary hematopoiesis is poikilocytosis, or the presence of abnormally shaped red blood cells.
== Personal life == On 5 July 2008, Emma Griffiths married Busted member Matt Willis at Rushton Hall, Northamptonshire, after three years of dating. The wedding was featured in OK magazine. She gave birth to their first child, a daughter named Isabelle, on 20 June 2009. On 25 November 2011, the couple had a second child, a son named Ace. On 4 May 2016, Willis gave birth to their third child, a second daughter, named Trixie Grace. In an episode of Who Do You Think You Are?, Willis confirmed that she has longstanding roots in Birmingham, with her family tree being traced back to her great-great-great-grandfather, who was named James Gretton and was listed as a Horn and Hair Merchant in the census records. She also found she had Irish ancestors, a fact that came as a surprise to her. The revelations about her ancestry left her extremely uncomfortable with the actions of one, who she discovered was a violent Orangeman, but overall, she was happy to have found a connection to her more broad Irish heritage. Willis is a supporter of Aston Villa. In August 2019, Willis obtained a qualification as a maternity care assistant following her experience on the W series Delivering Babies. During the COVID-19 pandemic in March 2021, Willis and her husband completed training with St John Ambulance to act as vaccination volunteers. In May 2023, Willis was featured in the documentary, Matt Willis: Fighting Addiction. The documentary, which aired on the BBC on 17 May 2023, followed Willis and her husband as they spoke about the latter's addiction issues.
Bromazepam is commonly involved in drug overdoses. A severe bromazepam benzodiazepine overdose may result in an alpha pattern coma type. The toxicity of bromazepam in overdosage increases when combined with other CNS depressant drugs such as alcohol or sedative hypnotic drugs. Similarly to other benzodiazepines however, being a positive modulator of certain neuroreceptors and not an agonist, the product has reduced overdose potential compared to older products of the barbiturate class. Its consumption alone is very seldom fatal in healthy adults. Bromazepam was in 2005 the most common benzodiazepine involved in intentional overdoses in France. Bromazepam has also been responsible for accidental poisonings in companion animals. A review of benzodiazepine poisonings in cats and dogs from 1991 to 1994 found bromazepam to be responsible for significantly more poisonings than any other benzodiazepine.
Sources: en.wikipedia.org
Patients may be advised to limit alcohol consumption, stop smoking, and practice good dental hygiene. It is also advised for individuals who take bisphosphonates to never allow the tablet to dissolve in the mouth as this causes damage to the oral mucosa.
A refrigerator car (or "reefer") is a refrigerated boxcar (US), a piece of railroad rolling stock designed to carry perishable freight at specific temperatures. Refrigerator cars differ from simple insulated boxcars and ventilated boxcars (commonly used for transporting fruit), neither of which are fitted with cooling apparatus. Reefers can be ice-cooled, come equipped with any one of a variety of mechanical refrigeration systems, or use carbon dioxide (as dry ice) or liquid nitrogen as a cooling agent. Milk cars (and other types of "express" reefers) may or may not include a cooling system, but are equipped with high-speed trucks and other modifications that allow them to travel with passenger trains.
Removing the algae underwater without disrupting native flora is accomplished by humans diving underwater and manually removing the reproductive parts of the wakame to reduce its spread. Proper and regular cleaning of underwater apparatus reduces the potential vectors for wakame spores, reducing the spread of the seaweed.
Sources: en.wikipedia.org
Southern Rhodesia had long been distinctive among British dependencies in that it had financed and developed its own security forces and command structure. After UDI, this posed a particular dilemma for the British government, which considered and rejected various proposals aimed at ending Rhodesia's state of rebellion by force. Harold Wilson once remarked that bringing an end to Rhodesian independence "would not be a case of arresting a subversive individual. It would mean a bloody war, and probably a bloody war turning into a bloody civil war." The formidable nature of the Rhodesian security forces, as well as British fears of a direct South African intervention on behalf of the rogue colony, preempted the further consideration of military options. For much of its existence, Rhodesia maintained a small professional standing army of 3,400 troops, about a third of whom were black volunteers. In the tradition of many colonial armies, it was primarily organised into light infantry battalions trained and equipped for counter-insurgency warfare or internal security actions, and possessed little artillery or armour. The Royal Rhodesian Air Force (RRAF) had 1,000 personnel and six squadrons of aircraft, including forty to fifty Hawker Hunter and de Havilland Vampire strike aircraft and English Electric Canberra light bombers. It also possessed a helicopter squadron, a transport squadron, and a light reconnaissance squadron.
==== MeSH D12.776.467.374.200 – chemokines ==== MeSH D12.776.467.374.200.070 – beta-thromboglobulin MeSH D12.776.467.374.200.100 – chemokines, c MeSH D12.776.467.374.200.110 – chemokines, cc MeSH D12.776.467.374.200.120 – chemokines, cxc MeSH D12.776.467.374.200.130 – chemokines, cx3c MeSH D12.776.467.374.200.508 – interleukin-8 MeSH D12.776.467.374.200.600 – macrophage inflammatory proteins MeSH D12.776.467.374.200.600.500 – macrophage inflammatory protein-1 MeSH D12.776.467.374.200.610 – monocyte chemoattractant proteins MeSH D12.776.467.374.200.610.600 – monocyte chemoattractant protein-1 MeSH D12.776.467.374.200.700 – platelet factor 4 MeSH D12.776.467.374.200.750 – rantes
=== tRNA === Ψ is ubiquitous in this class of RNAs and facilitates common tRNA structural motifs. One such structural motif is the TΨC stem loop which incorporates Ψ55. Ψ is commonly found in the D stem and anticodon stem and loop of tRNAs from each domain. In each structural motif, the unique physicochemical properties of Ψ stabilize structures that would not be possible with the standard U. During translation, Ψ modulates interactions of tRNA molecules with rRNAs and mRNAs. Ψ and other modified nucleotides affect the local structure of the tRNA domains they are found in, without impacting the overall fold of the RNA. In the anticodon stem-loop (ASL), Ψ seems critical for proper binding of tRNAs to the ribosome. Ψ stabilizes the dynamic structure of the ASL and promotes stronger binding to the 30S ribosome. The stabilized conformation of the ASL helps maintain correct anticodon-codon pairings during translation. This stability may increase translational accuracy by decreasing the rate of peptide bond formation and allowing for more time for incorrect codon-anticodon pairs to be rejected. Despite Ψ's role in local structure stabilization, pseudouridylation of tRNA is not essential for cell viability and is not usually required for aminoacylation.
Sources: en.wikipedia.org
No regulatory agency has authorised melanotan-2 as a medicine for any indication. It circulates mainly as a research chemical or through unregulated channels. As a result, identity, purity and content are not independently guaranteed.
Melanotan-1, also called afamelanotide, is a linear analogue with greater selectivity for MC1R and has received approval in some jurisdictions for a specific photosensitivity disorder. Melanotan-2 is cyclic, less selective, and reaches central receptors more readily. The two are often confused in online discussion despite different pharmacology and regulatory status.
Alpha-MSH is an endogenous tridecapeptide derived from pro-opiomelanocortin. Melanotan-2 reproduces its core receptor-binding sequence inside a shortened, stabilised ring. The result is a molecule with a longer effective half-life and higher potency than the parent hormone.
No. No major regulatory agency has granted a marketing authorisation for melanotan II as a medicine. Products sold under this name are generally presented as laboratory reagents and are not subject to the batch-release testing applied to approved drugs.