cyclic heptapeptide raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-04-14. Anything still debated is marked as such rather than presented as settled.
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.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, which separates the target peptide from truncated or oxidised impurities. Mass spectrometry, most often coupled to liquid chromatography, confirms molecular mass and detects substitutions that chromatography alone may miss. Amino acid analysis and peptide mapping supply additional structural evidence, while nuclear magnetic resonance is reserved for full structural confirmation. Laboratories that examine samples sold online report wide variation in actual content, with some vials containing little or none of the labelled material.
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controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports.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-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
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.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | -20 °C or below | For the lyophilised powder, desiccated |
| Storage form | Sealed vial, protected from light | Amber glass or foil-wrapped containers |
| Reconstituted stability | Short, refrigerate | Degradation accelerates in solution |
| Typical analytical method | Reversed-phase HPLC with mass spectrometry | Purity assessment plus identity confirmation |
| Common synonyms | Melanotan II, MT-II | Also written melanotan-2 |
Regulatory treatment varies by jurisdiction and has changed over time. In several countries the peptide is handled as an unapproved prescription medicine, and import or sale for human use is restricted, while elsewhere it falls under poisons or controlled-substance schedules. Enforcement activity against online vendors has been reported in Australia, New Zealand, the United Kingdom and the United States. Scholarly writing discusses melanotan-2 chiefly as an experimental tool and as a case study in unregulated peptide supply, and its precise legal position in any given country should be checked against current national schedules.
Lyophilised melanotan-2 is comparatively robust when kept dry, cold and dark, and a desiccated powder stored at minus twenty degrees Celsius or below is generally expected to retain its chemical integrity for extended periods. In solution the peptide is far less stable, with degradation proceeding through oxidation of tryptophan and histidine residues, hydrolysis adjacent to the lactam bridge, and aggregation at higher concentrations. Repeated freeze-thaw cycling accelerates loss of the parent peak. Working aliquots are therefore prepared once, held cold, and used without letting the stock return to ambient temperature.
Quality assessment of research-grade peptide rests mainly on reversed-phase high-performance liquid chromatography for purity and on mass spectrometry for identity confirmation. A single main peak above a stated threshold, commonly ninety-eight percent by peak area, is the usual release criterion applied by suppliers. Independent analyses commissioned by laboratories and consumer organisations have repeatedly reported discrepancies between label claims and measured content, including truncated sequences, residual trifluoroacetate, and lower-than-declared peptide mass. Those findings do not establish that every supplier is unreliable, but they indicate that purity figures printed on a vial are claims requiring verification rather than settled facts.
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.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry. Retention time supports identity, while the mass spectrum confirms the molecular weight of the intact peptide. Purity is frequently reported as a percentage of total peak area, a figure that depends on the wavelength, column and gradient used. Impurity profiling may also look for truncated sequences, oxidised forms and residual counterions. Amino acid analysis and peptide mapping provide orthogonal confirmation when required.
Regulatory status varies by jurisdiction, and the substance is frequently described as unapproved for therapeutic use. Some authorities classify it alongside prescription-only medicines or controlled categories, while others address it through general consumer protection rules. Analytical surveys have reported mismatches between label claims and measured content in products sold online, although the scope of such testing is limited. Whether these discrepancies are widespread remains an open question. Discussion in the literature therefore tends to combine chemistry, supply-chain observation and policy analysis.
The material is commonly handled as a lyophilized powder in sealed vials. The solid dissolves readily in water and in polar organic solvents, producing a clear solution after reconstitution. Light, heat and repeated freeze-thaw cycles are the concerns most often raised in handling guidance, because peptide bonds and the constrained ring can degrade. Working solutions are generally prepared fresh, and material left in solution is treated as less stable than the dry form. These properties shape how laboratories store and aliquot reference material.
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.
== Genetics == AGAT deficiency is caused by deficient activity of arginine:glycine amidinotransferase, which is coded for by GATM, located on the long arm of chromosome 15. AGAT deficiency is inherited in an autosomal recessive manner, which means pathogenic variants must be inherited from each parent. This enzyme catalyzes the first step in creatine biosynthesis, the combination of arginine and glycine to form guanidinoacetate, which also results in the formation or ornithine as a by product. These reactions take place primarily in the kidney and pancreas. The clinical manifestations of AGAT deficiency are caused by the decreased amounts of creatine produced.
The sodium–potassium pump (sodium–potassium adenosine triphosphatase, also known as Na+/K+-ATPase, Na+/K+ pump, or sodium–potassium ATPase) is an enzyme (an electrogenic transmembrane ATPase) found in the cell membrane of all animal cells. It performs several functions in cell physiology. The Na+/K+-ATPase enzyme is an enzyme involved in active transport (i.e. it uses energy from ATP). For every ATP molecule that the pump uses, three sodium ions are exported and two potassium ions are imported. Thus, there is a net export of a single positive charge per pump cycle. The net effect is an extracellular concentration of sodium ions 5 times the intracellular concentration, and an intracellular concentration of potassium ions 30 times the extracellular concentration. The sodium–potassium pump was discovered in 1957 by the Danish scientist Jens Christian Skou, who was awarded a Nobel Prize for his work in 1997. Its discovery marked an important step forward in the understanding of how ions get into and out of cells, and its particular significance for excitable cells such as nerve cells, which depend on this pump to respond to stimuli and transmit impulses. All mammals have four different sodium pump sub-types, or isoforms. Each has unique properties and tissue expression patterns. Sodium–potassium ATPase belongs to the family of P-type ATPases.
Hyaluronan degradation products then accumulate in the skin after UV exposure. While it is abundant in extracellular matrices, hyaluronan also contributes to tissue hydrodynamics, movement, and proliferation of cells and participates in a number of cell surface receptor interactions, notably those including its primary receptors, CD44 and RHAMM. Upregulation of CD44 itself is widely accepted as a marker of cell activation in lymphocytes. Hyaluronan's contribution to tumor growth may be due to its interaction with CD44. Receptor CD44 participates in cell adhesion interactions required by tumor cells. Although hyaluronan binds to receptor CD44, there is evidence hyaluronan degradation products transduce their inflammatory signal through toll-like receptor 2 (TLR2), TLR4, or both TLR2 and TLR4 in macrophages and dendritic cells. TLR and hyaluronan play a role in innate immunity. There are limitations including the in vivo loss of this compound limiting the duration of effect.
Erythromycin, ketoconazole and cyclosporine are CYP3A4 inhibitors and therefore inhibit the metabolic pathway of docetaxel. When used with anticonvulsants, which induce CYP3A4, an increased dose of docetaxel may be required. Pre-treatment with corticosteroids has been used to decrease hypersensitivity reactions and oedema in response to docetaxel and has shown no effect on the pharmacokinetics of docetaxel. The efficacy of docetaxel was improved by treatment with oral capecitabine, and after more than 27 months follow-up the survival benefit has been confirmed. Doxorubicin was combined with docetaxel in one study of 24 patients and resulted in an increased AUC of docetaxel by 50 to 70%, indicating doxorubicin may affect the disposition of docetaxel. Etoposide has also been shown to decrease docetaxel clearance, though patient numbers for this observation have been low. Prednisone given with docetaxel led to improved survival, quality of life and pain management in patients with hormone-refractory prostate cancer.
== Businesspeople == Henry Rutgers (1766), Revolutionary War hero, businessman, philanthropist, and namesake of Rutgers University Leffert Lefferts (1794), first president of Long Island Bank William Bard (1798), son of physician Samuel Bard, founder and first president of New York Life Insurance Company Stephen Price (1799), theatrical manager who managed Park Theatre in Manhattan and Theatre Royal, Drury Lane in London William Backhouse Astor Sr.* (1811), son of John Jacob Astor Cornelius Roosevelt* (attended, year unknown), member of the Roosevelt family, one of the founders of the Chemical Bank; great-grandfather of Theodore Roosevelt James H. Roosevelt (1819), founder of Roosevelt Hospital Robert Goelet Sr. (1828), banker and real estate developer who was associated with the founding of the Chemical Bank Bradish Johnson (1831), industrialist involved in the Swill milk scandal Robert L. Cutting (1830), co-founder of the Continental Bank of New York and president of the New York Stock Exchange Henry T. Anthony (1832), photographer, vice-president of the E. & H. T. Anthony & Company Adrian G Iselin* (1837), financier, banker Edward Anthony (1838), photographer and founder of E. & H. T. Anthony & Company, largest manufacturer and distributor of photographic supplies in the U.S. during the 19th century John Jacob Astor III (1839), son of William Backhouse Astor Sr.
Sources: en.wikipedia.org
Federal Government systems for the electronic exchange of clinical health information. In 1999, it was identified by the HL7 Standards Development Organization as a preferred code set for laboratory test names in transactions between health care facilities, laboratories, laboratory testing devices, and public health authorities.
(1936), Recollections and Reflections, London: G. Bell & Sons, Ltd. Republished as digital edition, Cambridge: University Press, 2011 (Cambridge Library Collection series). Thomson, George Paget. (1964) J.J. Thomson: Discoverer of the Electron. Great Britain: Thomas Nelson & Sons, Ltd. Davis, Eward Arthur & Falconer, Isobel (1997), J.J. Thomson and the Discovery of the Electron. ISBN 978-0-7484-0696-8 Falconer, Isobel (1988) "J.J. Thomson's Work on Positive Rays, 1906–1914" Historical Studies in the Physical and Biological Sciences 18(2) 265–310 Falconer, Isobel (2001) "Corpuscles to Electrons" in J Buchwald and A Warwick (eds) Histories of the Electron, Cambridge, Mass: MIT Press, pp. 77–100. Navarro, Jaume (2005). "J. J. Thomson on the Nature of Matter: Corpuscles and the Continuum". Centaurus. 47 (4): 259–282. Bibcode:2005Cent...47..259N. doi:10.1111/j.1600-0498.2005.00028.x. Downard, Kevin M. (2009). "J. J. Thomson goes to America". Journal of the American Society for Mass Spectrometry. 20 (11): 1964–1973. Bibcode:2009JASMS..20.1964D. doi:10.1016/j.jasms.2009.07.008. PMID 19734055. S2CID 34371775.
The M Series (e.g., 2GO Maligaya, 2GO Masagana), named after Filipino words beginning with "Ma" that represent positive traits and attitudes of the Filipino people.) The S Series (e.g., St. Michael the Archangel, St. Francis Xavier), named after Roman Catholic saints.)
September 21, 2009: Republic of Macedonia The Republic of Macedonia officially enters the recession after experiencing a drop in GDP of 0.9% in the first quarter, followed by 1.4% in the second quarter.
A band cell (also called band neutrophil, band form or stab cell) is a cell undergoing granulopoiesis, derived from a metamyelocyte, and leading to a mature granulocyte. It is characterized by having a curved but not lobular nucleus. The term "band cell" implies a granulocytic lineage (e.g., neutrophils).
Sources: en.wikipedia.org
==== The possibility of using two mixtures in the synthesis ==== In principle, the use of two mixtures in the S&P synthesis can lead to the same combinatorial library that forms in the usual S&P method. The differences in the reactivity of BBs however, bring about large differences in the concentrations of components, and the differences are expected to increase after each step. Although a considerable amount of labor could be saved by using the two mixtures approach when a high number of BBs are coupled in each position, it is advisable to stick to the normally used S&P procedure.
=== Glycoprotein VI (GPVI) === Glycoprotein VI is one of the immunoglobulin superfamily type I transmembrane glycoproteins. It is an important collagen receptor involved in collagen-induced platelet activation and adhesion. It plays a key role in their procoagulant activity and subsequent thrombin and fibrin formation. Its procoagulant function may contribute to arterial or venous thrombosis. The FCR pathway of GPVI activation involves γ chain (GPVI transmembrane domain associates with γ chain FCR), Src kinase FYN / LYN, and LAT adaptor protein, all participating in phospholipase C activation.
Plasma concentrations of methadone in recovering addicts can reach 4 μM during therapy, so the actions of methadone at both the hERG potassium channel and the Nav1.5 sodium channel are possibly clinically relevant in producing cardiac side effects. This also suggests that levomethadone is not completely free of cardiac toxicity.
The use of fetal tissue in vaccine development is the practice of researching, developing, and producing vaccines through growing viruses in cultured (laboratory-grown) cells that were originally derived from human fetal tissue. Since the cell strains in use originate from abortions, there has been some opposition to the practice and the resulting vaccines on religious and moral grounds. The Roman Catholic Church is opposed to abortion. Nevertheless, the Pontifical Academy for Life stated in 2017 that "clinically recommended vaccinations can be used with a clear conscience and that the use of such vaccines does not signify some sort of cooperation with voluntary abortion". On 21 December 2020, the Vatican's doctrinal office, the Congregation for the Doctrine of the Faith, further clarified that it is "morally licit" for Catholics to receive vaccines derived from fetal cell lines or in which such lines were used in testing or development, because "passive material cooperation in the procured abortion from which these cell lines originate is, on the part of those making use of the resulting vaccines, remote" and "does not and should not in any way imply that there is a moral endorsement of the use of cell lines proceeding from aborted fetuses".
At the beginning of the North African campaign, Brigadier General Lyman L. Lemnitzer accompanied Major General Mark Wayne Clark by submarine to North Africa. Upon arrival, about 60 officers were awarded the Legion of Merit and were among the first awarded the medal. By some misunderstanding as to the rules governing the awards, these 60 American officers were awarded the degree of Officer. According to Lemnitzer, President Roosevelt was quite annoyed but did not rescind the awards. These were the only U.S. officers (or service personnel of any rank) awarded the Legion of Merit with a degree. In 1943 Willem Jan Kruys received the Legion of Merit (Officer) in Australia as captain of the Dutch destroyer HMNS Tjerk Hiddes for the three rescue trips to Timor in December 1942 during which 1100 people were saved from the beaches of Timor under Japanese occupation. The certificate was signed by President Roosevelt personally. In 1960 Kruys received the Legion of Merit again when retired as vice-admiral of the Royal Dutch Navy, this time with gold star and combat V. In March 1945, Colonel Hsieh Mang, of the Chinese Army was awarded the Legion of Merit for his work with the First American Volunteer Group "Flying Tigers". In 1945, Lieutenant Colonel William E. Fairbairn, a former British General Service Corps who transferred to United States as "officer in rent" to train SOE agents and later the Office of Strategic Services (OSS), for his achievements in training OSS personnel. Fairbairn eventually rose to the rank of lieutenant-colonel by the end of the war, and received the U.S.
Sources: en.wikipedia.org
The lyophilised solid is best kept cold, dry and dark, typically at minus twenty degrees Celsius. Moisture and repeated warming cycles are the main causes of degradation. Solutions prepared from the powder are less stable and are normally used quickly.
Reversed-phase liquid chromatography assesses purity, while mass spectrometry confirms molecular mass and detects sequence errors. Amino acid analysis and peptide mapping add structural detail. These techniques are complementary rather than interchangeable.
It is listed as a prohibited peptide hormone by the World Anti-Doping Agency. No medicines regulator has approved it for human use. Import and sale rules vary by country.
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.