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.
Last reviewed on 2025-09-15. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
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.
Melanocortin receptors comprise five subtypes with distinct tissue distributions and functions. Melanotan-2 is described in the literature as a non-selective agonist that engages several of these subtypes, including MC1R, MC3R, MC4R, and MC5R. MC1R is the subtype most directly linked to melanin production in skin cells. Because the compound is not subtype-selective, its observed effects in experimental settings are generally attributed to activity across multiple receptor pathways rather than to a single target.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analogue of alpha-melanocyte-stimulating hormone |
| Common synonyms | MT-II; melanotan 2 | No internationally accepted non-proprietary name |
| Typical presentation | Lyophilised powder in a sealed vial | Often supplied alongside a separate diluent |
| Regulatory status | Unapproved therapeutic substance | Customs seizure reported in several jurisdictions |
| Reported route in use | Subcutaneous injection | Self-administered outside clinical settings |
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its sequence incorporates modified residues that increase potency and extend biological activity relative to the native hormone. The compound binds receptors of the melanocortin family and is examined mainly in laboratory research. It does not occur naturally and exists only as a manufactured chemical entity produced by solid-phase synthesis.
The peptide was developed during the 1980s by researchers investigating melanocortin signalling and skin pigmentation pathways. Early work focused on analogues of alpha-melanocyte-stimulating hormone that would resist enzymatic breakdown more effectively than the parent molecule. Melanotan-2 emerged from that programme as a shortened, cyclised variant. Reports describing its synthesis and receptor activity later appeared in the scientific literature. Commercial availability grew through unregulated channels rather than through pharmaceutical approval.
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.
The steps of direct ELISA follows the mechanism below: A buffered solution of the antigen to be tested for is added to each well (usually 96-well plates) of a microtiter plate, where it is given time to adhere to the plastic through charge interactions. A solution of non-reacting protein, such as bovine serum albumin or casein, is added to each well in order to cover any plastic surface in the well which remains uncoated by the antigen. The primary antibody with an attached (conjugated) enzyme is added, which binds specifically to the test antigen coating the well. A substrate for this enzyme is then added. Often, this substrate changes color upon reaction with the enzyme. The higher the concentration of the primary antibody present in the serum, the stronger the color change. Often, a spectrometer is used to give quantitative values for color strength. The enzyme acts as an amplifier; even if only a few enzyme-linked antibodies remain bound, the enzyme molecules will produce many signal molecules. Within common-sense limitations, the enzyme can go on producing color indefinitely, but the more antibody is bound, the faster the color will develop. A major disadvantage of the direct ELISA is that the method of antigen immobilization is not specific; when serum is used as the source of test antigen, all proteins in the sample may stick to the microtiter plate well, so small concentrations of analyte in serum must compete with other serum proteins when binding to the well surface.
Boehringer Ingelheim Austria has validated a method with cGMP (commercial good manufacturing practices) for production of pharmaceutical-grade DNA plasmids. They are able to process 200L of fermentation broth on an 800mL monolith. At BIA Separations, processing time of the tomato mosaic virus decreased considerably from the standard five days of manually intensive work to equivalent purity and better recovery in only two hours with a monolith column. Other viruses have been purified on monoliths as well. Affinity monoliths have also been applied to the isolation of nanoscale particles from human plasma. Tandem monolithic disks functionalized with chondroitin-6-sulfate and anti-apolipoprotein B-100 antibodies enabled the selective isolation of low-density lipoprotein in less than 30 minutes, while a monolith carrying an anti-CD61 antibody isolated platelet-derived extracellular vesicles in 19 minutes. Monolithic disks carrying antibodies against apoB-100, CD9, or CD61 were subsequently coupled online to asymmetric flow field-flow fractionation, allowing automated isolation and size fractionation of lipoproteins and extracellular-vesicle subpopulations. Extracellular-vesicle fractions obtained using these monolith-based systems have also been characterized by Raman spectroscopy and comprehensive two-dimensional gas chromatography, and used in quartz crystal microbalance studies of binding between extracellular-vesicle subpopulations and affinity ligands.
Narrated by John Hedges, produced by Brian Johnson, made by Uden Associates 23 September Trouble on the Line, with Richard Hope and Roger Ford rail journalists, Chris Green, the Head of Network SouthEast; mention of a possible Crossrail and the new Thameslink, which was a redeveloped former freight tunnel; Andrew Higton; Bob Walters the InterCity 225 project engineer; London had the biggest commuter system in world; Borough Market Junction is a bottleneck; Jim Vine head of the new Networker train project; BR carried 700 million people; 134,000 BR employees; at Department of Transport 2300 worked on the roads, and 135 on rail; Dornoch Firth Bridge (A9), shown being built, it saved twenty miles, and could have had a rail bridge too for the Far North Line. Narrated by Anthony Valentine 30 September Fly-by-wire: Technology on Trial 7 October The Light Stuff, about a human-powered aircraft from Santorini to Crete, the MIT Daedalus; the title is from The Right Stuff; the project had taken three years, to fly across the Aegean Sea; the aircraft weighed around 30 kg; to gain the Kremer prize, SUMPAC of the University of Southampton made the first human-powered flight in November 1961, followed by HMPAC Puffin, of de Havilland in Hertfordshire, in May 1962; the Bristol Jupiter flew in 1972; in 1977 Paul MacCready designed his Condor, and his Albatross flew across the English Channel on 12 June 1979, with Bryan Allen; John Langford of MIT developed the Monarch aircraft in 1983, which flew at 21 mph; the Daedalus project began in 1985, to make a 72 mile flight; Steven R.
Sources: en.wikipedia.org
=== Migration of can components === In canning toxicology, migration is the movement of substances from the can itself into the contents. One toxic substance that can migrate is lead, which causes lead poisoning, but has been phased out of usage in cans since the 20th century. A newer concern is bisphenol A (BPA), a potential endocrine disruptor that is an ingredient in the epoxy commonly used to coat the inner surface of cans. Some cans are manufactured with a BPA-free enamel lining produced from plant oils and resins. In February 2018, the Can Manufacturers Institute, a trade association in the United States, surveyed the industry and reported that at least 90% of food cans no longer contained BPA.
Where several alkaloids are extracted from one plant their names are often distinguished by variations in the suffix: "idine", "anine", "aline", "inine" etc. There are also at least 86 alkaloids whose names contain the root "vin" because they are extracted from vinca plants such as Vinca rosea (Catharanthus roseus); these are called vinca alkaloids.
Since then, the species name Naja/Hoplocephalus bungaroides, originally coined for the king cobra and improperly assigned to the broad-headed snake, became conflated with the broad-headed snake and used as the type species of Hoplocephalus, while the species name Naja bungarus was treated as a junior synonym of the king cobra (until its revival as the species name for the Sunda king cobra in 2024). This longstanding discrepancy, which breaks the principle of priority, was overlooked for nearly two centuries and only discovered in 2024. Due to the long presence of the names Ophiophagus hannah and Hoplocephalus bungaroides in the literature, which would be upended if these two species were reclassified based on this issue, it was decided to maintain the longstanding scientific names for both taxa and designate a new, accurate type specimen for the broad-headed snake.
Sources: en.wikipedia.org
where λz is the slope of the terminal phase of the time–concentration curve for the substance on a semilogarithmic scale. Half-life is determined by clearance (CL) and volume of distribution (VD) and the relationship is described by the following equation:
Several scientists, such as William Prout and Norman Lockyer, had suggested that atoms were built up from a more fundamental unit, but they envisioned this unit to be the size of the smallest atom, hydrogen. Thomson in 1897 was the first to suggest that one of the fundamental units of the atom was more than 1,000 times smaller than an atom, suggesting the subatomic particle now known as the electron. Thomson discovered this through his explorations on the properties of cathode rays. Thomson made his suggestion on 30 April 1897 following his discovery that cathode rays (at the time known as Lenard rays) could travel much further through air than expected for an atom-sized particle. He estimated the mass of cathode rays by measuring the heat generated when the rays hit a thermal junction and comparing this with the magnetic deflection of the rays. His experiments suggested not only that cathode rays were over 1,000 times lighter than the hydrogen atom, but also that their mass was the same in whichever type of atom they came from. He concluded that the rays were composed of very light, negatively charged particles which were a universal building block of atoms. He called the particles "corpuscles", but later scientists preferred the name electron, which had been suggested by George Johnstone Stoney in 1891, prior to Thomson's discovery. In April 1897, Thomson had only early indications that the cathode rays could be deflected electrically (previous investigators such as Heinrich Hertz had thought they could not be).
==== Metabolism ==== More than 95% of a dose of tizanidine is metabolized. The primary cytochrome P450 enzyme involved in the metabolism of tizanidine is CYP1A2. Strong CYP3A4 inhibitors such as fluvoxamine and ciprofloxacin can increase tizanidine exposure by 10- to 33-fold, indicating the key involvement of CYP1A2 in the metabolism of the drug. The metabolites of tizanidine are thought to be inactive.
== History == Students Michael Schrader, Livio Valenti, Kathryn Kosuda, and Patrick Ho started Vaxess in December 2011, based on a technology created by David Kaplan and Fiorenzo Omenetto. Schrader graduated with an MBA from Harvard Business School in 2012. Valenti attended the John F. Kennedy School of Government. Kosuda had been a Harvard postdoctoral fellow in chemistry, and Patrick Ho had earned a J.D in 2012. In 2012, Vaxess was awarded $25,000 from Harvard Business School for Harvard's Business Plan Contest in the Business Ventures Track. Vaxess Technologies was a semi-finalist for MIT's $100K Entrepreneurship Competition in the Life Sciences section. In 2012, it won the Harvard President's Challenge in the Global Health section and was awarded $70,000. The company was selected as a finalist for two 2013 MassTLC Awards, Start-Up to Watch and Innovative Technology of the Year: Healthcare/Life Sciences. In May 2013, Vaxess received $3.75M in funding from Norwich Ventures and an undisclosed amount of money from angel investor Jeffrey Walker. In August 2013, the company announced that it would be moving out of Harvard's Innovation Lab to a new location at LabCentral in Cambridge. In December 2013, the Massachusetts Life Sciences Center awarded $1.5M to local startups. Vaxess received $1M of that amount which is the most that the MLSC's Accelerator Loan Program will lend to one organization.
Sources: en.wikipedia.org
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.
It was developed in the 1980s by researchers investigating analogues of alpha-melanocyte-stimulating hormone for pigmentation and related endpoints. Early work included small human studies during the 1990s. Development did not progress to licensing, and the compound remained a research and grey-market item.
Peptides are prone to truncation, oxidation and aggregation during synthesis and handling. Without independent testing, a buyer cannot confirm the identity or the content of a vial. Analytical surveys of unapproved peptide products have repeatedly found discrepancies between label claims and measured composition.
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.