Everything below concerns LC-MS/MS. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-01-09. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Regulatory treatment of this peptide varies by country. It holds no marketing authorization as a medicine in the United States, the European Union, or most other jurisdictions. Some countries classify products containing it as prescription-only or unlicensed medicines, which restricts lawful supply. Authorities have issued public notices warning that unregulated products may contain undeclared or incorrect ingredients. The molecule also appears on prohibited lists for competitive sport. These measures address supply oversight rather than any approved therapeutic role.
Published research on the compound remains limited. Much of the human data comes from small, early-stage studies rather than large controlled trials, and several questions about effects and variability between individuals remain open. Investigators have examined receptor activity, pigment pathways, and related physiological responses in laboratory and animal models. Findings from those models do not automatically translate to human outcomes. Reviews frequently note the scarcity of rigorous clinical evidence and call for better-characterized study material.
Because the substance circulates mainly through informal markets, verification is a recurring theme in technical discussion. Independent analyses have found that labeled content and actual content can diverge, and that purity varies between samples. Analytical laboratories use reversed-phase chromatography to separate components and mass spectrometry to confirm identity. Isotope-labeled internal standards improve quantification in complex matrices. Such methods describe what a sample contains but say nothing about its sterility, lawful status, or suitability for any use. Open questions remain about how consistently testing is applied across the supply chain.
| 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-2 is a synthetic peptide designed as an analog of alpha-melanocyte-stimulating hormone, a signaling molecule produced in the pituitary and skin. Its structure is a linear chain of seven amino acids that folds into a ring through an internal lactam bridge joining two side chains. The compound is sometimes written as MT-II or MEL-2 in informal and commercial contexts. It belongs to the melanocortin peptide family, a group of short signaling molecules that share a conserved core sequence recognized by melanocortin receptors.
Two structural changes distinguish the synthetic peptide from the natural hormone. A norleucine residue replaces methionine at one position, and a D-configured phenylalanine replaces the natural L-form at another. Both substitutions slow enzymatic breakdown, which extends the molecule's persistence relative to the parent hormone. The lactam bridge further constrains the backbone into a stable conformation. These features are standard design strategies in peptide chemistry and are not unique to this compound; they appear across many research peptides built for improved stability.
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.
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.
Lyophilised peptide powder is comparatively stable when kept dry, cold and protected from light. Once dissolved, the molecule is exposed to hydrolysis, oxidation and microbial growth, and degradation accelerates at higher temperatures and in alkaline solution. Repeated freeze-thaw cycles concentrate solutes and promote aggregation. Handling guidance for research peptides commonly clusters around freezer temperatures for powder and short refrigerated use for reconstituted solutions, with pH control and sterile technique applied throughout.
Verification of a purchased sample requires documentation linking a batch to a certificate of analysis, and that document should be read for the methods used rather than the headline purity figure. A single chromatographic percentage does not establish identity. Independent laboratories can perform identity and content assays, but no such test establishes that a product is suitable for human use. Claims about efficacy rest largely on small, early studies rather than on replicated controlled trials, and that gap remains open.
== Principle == Cholecystokinin (CKK) is a peptide hormone secreted by I-cells in the intestinal mucosa. It stimulates the secretion of pancreatic fluid into the duodenum through the sphincter of oddi. This fluid is rich in pancreatic enzymes amylase, trypsin, and lipase. It also promotes contraction and relaxation of the gallbladder. Secretin is a peptide hormone that stimulates the secretion of both pancreatic fluid and bicarbonate. The Secretin-cholecystokinin test is considered the gold standard test of pancreatic exocrine function. It is now rarely used in adults in favour of non-invasive tests, though it is still used in some cases in infants with pancreatic insufficiency to distinguish between cystic fibrosis and Schwachman-Diamond syndrome.
British soldiers were fed freshly cooked meals when in camp or barracks and troops on deployment could eat meals from field kitchens whenever possible, but soldiers were also reliant on rations. The British Army issued 24-hour rations intended to sustain troops until composite rations and fresh food could be supplied by field kitchens. An example of such a 24 hour ration pack issued to British and Commonwealth soldiers contained the following: 10 biscuits, two oatmeal blocks, milk, sugar, and tea blocks, four tablets of sugar, one block of meat, two pieces of raisin chocolate and one piece of plain chocolate, boiled sweets, one packet of salt, meat extract tablets, two packets of chewing gum, and four pieces of latrine paper. Composite rations, known as "compo" rations or 14-man rations, were designed to sustain 14 men for one day and came in wooden crates. A composite ration crate would include meats such as bully beef, sausage, spam, steak and kidney pudding, fruit pudding, treacle pudding, soup, beans, cheese, biscuits, jam, margarine, tea, powdered milk, and sugar. The composite ration was introduced at the end of the North African campaign to alleviate nutritional problems caused by Commonwealth rations in North African being largely bully beef and biscuits. Prior to its introduction tinned fruit had been introduced to improve nutrition. On the home front in Britain, mobile canteens were operated to provide Home Guard and civil defence authorities with hot food and fresh tea. A similar system applied to Canadian soldiers.
=== Supercritical fluid deposition === Supercritical fluids can be used to deposit functional nanostructured films and nanometer-size particles of metals onto surfaces. The high diffusivities and concentrations of precursor in the fluid as compared to the vacuum systems used in chemical vapour deposition allow deposition to occur in a surface reaction rate limited regime, providing stable and uniform interfacial growth. This is crucial in developing more powerful electronic components, and metal particles deposited in this way are also powerful catalysts for chemical synthesis and electrochemical reactions. Additionally, due to the high rates of precursor transport in solution, it is possible to coat high surface area particles which under chemical vapour deposition would exhibit depletion near the outlet of the system and also be likely to result in unstable interfacial growth features such as dendrites. The result is very thin and uniform films deposited at rates much faster than atomic layer deposition, the best other tool for particle coating at this size scale.
Sources: en.wikipedia.org
Insulin induced gene 1, also known as INSIG1, is a protein which in humans is encoded by the INSIG1 gene. INSIG1 is short for insulin-induced gene 1; it is located on chromosome 7 (7q36). This human gene encodes for a transmembrane protein of 277 amino acids with probably 6 transmembrane domains. It is localized in the endoplasmic reticulum (ER) and seems to be expressed in all tissues, especially in liver. This gene is called an insulin-induced gene because the molecule insulin can regulate it. Importantly, the protein encoded by this gene plays a critical role in regulating cholesterol concentrations in cells.
On May 23, 1871, at the instigation of anarchist Jean-Louis Pindy, Communards set fire to many public buildings, including Paris’ City Hall. The civil records, stored in an annex at 4 Avenue Victoria, were the first to burn. Within hours, the originals of civil and parish registers were destroyed, along with the collection of the Historical Library of Paris, which had been transferred to City Hall. Just days earlier, on May 17, 1871, Louise Michel had declared at the "Club de la Trinité": "Paris will be ours or will no longer exist!" On May 24, 1871, the day after City Hall’s destruction, Communards burned the Palais de Justice on orders from Blanquist Théophile Ferré. The second copies of civil and parish registers for Paris and all communes in the Seine were lost as well. Besides civil registry offices, much of the Palais was destroyed: the offices of the Court of First Instance; the General Prosecutor’s Office; the Public Prosecutor’s Office; judges’ chambers; two criminal courts (completed just two years earlier); much of the Court of Cassation; the Court of Appeal; the Great Hall and Grand Chamber; the Correctional Police; and the archives.
=== Mutation === A locus at 14q has been suggested, but no gene has been identified. A second locus has been identified on chromosome 8 and a third has been reported on chromosome 2. This suggests there may be some genetic heterogeneity in this disease. A mutation in the gene encoding the type III sodium dependent phosphate transporter 2 (SLC20A2) located on chromosome 8 has been reported. Biochemical evidence suggests that phosphate transport may be involved in this disease. Two other genes have been associated with this condition: PDGFB on chromosome 22 and PDGFRB on chromosome 5. These genes are biochemically linked: PDGFRB encodes the platelet-derived growth factor receptor β and PDGFB encodes the ligand of PDGF-Rβ. These genes are active during angiogenesis to recruit pericytes which suggests that alterations in the blood brain barrier may be involved in the pathogenesis of this condition. A fourth gene associated with this condition is XPR1. This gene is the long arm of located on chromosome 1 (1q25.3). Another gene that has been associated with this condition is MYORG. This gene is located on the long arm of chromosome 9 (9p13.3). This gene is associated with an autosomal recessive inheritance pattern in this condition. Another gene junctional adhesion molecule 2 (JAM2) has been associated with an autosomal recessive form of this condition. The most recently found gene to be associated with PFBC is Nα-acetyltransferase 60 (NAA60).
Sources: en.wikipedia.org
Favor was a "plastic, smoke-free product shaped and colored like a conventional cigarette that contained a filter paper soaked with liquid nicotine so users could draw a small dose by inhaling. There was no electricity, combustion, or smoke; it delivered only nicotine." Favor cigarettes were sold in California and several Southwestern states, marketed as "an alternative to smokers, and only to smokers, to use where smoking is unacceptable or prohibited." In 1987, the FDA exercised jurisdiction over products analogous to E-Cigarettes. Advanced Tobacco Products never challenged the Warning Letter and ceased all distribution of Favor. Ray's wife Brenda Coffee coined the term vaping. Philip Morris' division NuMark, launched in 2013 the MarkTen e-cigarette that Philip Morris had been working on since 1990.
In the absence of other glucogenic sources, the 2-carbon acetyl-CoA derived from the oxidation of fatty acids cannot produce a net yield of glucose via the citric acid cycle, since an equivalent two carbon atoms are released as carbon dioxide during the cycle. During ketosis, however, acetyl-CoA from fatty acids yields ketone bodies, including acetone, and up to ~60% of acetone may be oxidized in the liver to the pyruvate precursors acetol and methylglyoxal. Thus ketone bodies derived from fatty acids could account for up to 11% of gluconeogenesis during starvation. Catabolism of fatty acids also produces energy in the form of ATP that is necessary for the gluconeogenesis pathway.
An unexpected medical problem that happens during treatment with a drug or other therapy. Adverse events do not have to be caused by the drug or therapy, and they may be mild, moderate, or severe. (NCI) An AE is any untoward medical occurrence in a patient or clinical investigation subject administered a pharmaceutical product and that does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medicinal (investigational) product, whether or not related to the medicinal (investigational) product (see the ICH guidance for Clinical Safety Data Management: Definitions and Standards for Expedited Reporting). (ICH E6) Adverse reaction
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.
Only a small number of early-stage human studies have been reported, and most were limited in size and duration. No large late-stage program has established a general efficacy or safety profile. The evidence base is therefore thin compared with approved medicines.