cyclic heptapeptide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2026-03-12. Numbers and descriptions here follow the published literature rather than marketing material.
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, also written Melanotan II, is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, and the lactam bridge between the aspartate and lysine side chains constrains the peptide into a ring. This structural change increases receptor affinity and metabolic stability relative to the native hormone. The compound was created in the 1980s as a research tool for studying pigmentation biology.
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.
Scientific discussion of Melanotan-2 spans pharmacology, dermatology, and public-health literature. Laboratory studies examine its receptor binding and cellular effects, while clinical reports describe outcomes observed after unregulated use. These two bodies of work differ in rigour and intent. Peer-reviewed trials of the compound as a medicine are limited, so much of the available information comes from case reports and surveillance data. Authors frequently note the gap between experimental findings and real-world use.
Reported observations after unregulated use include shifts in skin pigmentation and, in some accounts, unintended changes to moles and other lesions. Whether these outcomes are causally linked to the compound, and how often they occur, remain open questions because controlled data are scarce. The absence of standardised dosing and verified product purity complicates interpretation. Researchers have called for better surveillance and analytical characterisation of samples obtained outside regulated channels. Conclusions drawn from anecdotal evidence should be treated as provisional.
| Property | Value | Notes |
|---|---|---|
| Compound class | Synthetic cyclic heptapeptide | Alpha-MSH analogue containing a D-phenylalanine residue |
| Molecular formula | C50H69N15O9 | Average molecular mass approximately 1024.2 g/mol |
| Appearance | White to off-white lyophilised powder | Normally supplied as a freeze-dried solid in a sealed vial |
| Solubility | Freely soluble in water and polar solvents | Dissolves readily in aqueous buffers and in alcohol-water mixtures |
| Receptor targets | MC1R, MC3R, MC4R, MC5R | Acts as a non-selective melanocortin receptor agonist |
Published human data come mostly from small, short studies rather than large controlled trials. Reported outcomes include increased skin pigmentation and, in some reports, effects on appetite and libido, but sample sizes are small and follow-up is limited. Whether long-term use produces durable pigment changes or adverse effects is not established. Because products sold outside pharmacies are not standardized, the actual content of any given vial is often unknown. Independent testing of such material is uncommon.
Melanotan II is a synthetic cyclic heptapeptide analog derived from the core sequence of alpha-melanocyte-stimulating hormone. Researchers at the University of Arizona synthesized it during the 1980s while studying pigmentation and appetite signaling. The compound is not an approved medicine in any major jurisdiction and appears mainly in laboratory and research-chemical settings. Its structure incorporates a lactam bridge between side chains, which constrains the ring and slows enzymatic breakdown relative to the natural hormone.
Analytical confirmation of identity relies on mass spectrometry, most often coupled to liquid chromatography. Reversed-phase high-performance liquid chromatography separates the peptide from related impurities and provides a purity estimate based on peak area. Electrospray ionization mass spectrometry then confirms the expected molecular mass, while tandem mass spectrometry can map the fragment sequence. For research-grade material, these two techniques together form the standard minimum. Purity figures reported by vendors are frequently not traceable to an independent laboratory.
Independent verification is central to quality control because the compound is not produced under pharmaceutical manufacturing standards. Third-party laboratories can measure purity, identity, residual solvents, and microbial contamination, though the scope of testing varies between services. Reported analyses of vendor samples have shown batch-to-batch variation in peptide content and the presence of truncated or oxidized species. How much of this variation reflects synthesis conditions versus storage and shipping is not well characterized. No harmonized reference standard exists for the material as sold.
== Price fixing investigation == It is known whether this apparent price fixing is actively being investigated, but the United States Department of Justice Antitrust Division Spring Update 2021 notes: "The Division remains committed to rooting out illegal conduct that corrupts critical healthcare markets. That work is more important now than ever before. The Division has uncovered price-fixing, bid-rigging, and customer-allocation schemes in one of the most important markets for the health and wallets of American consumers: the generic drug industry. Indeed, nearly 90% of all prescriptions in the United States are filled with generic drugs."
Fructose: 38% Glucose: 31% Sucrose: 1% Water: 17% Other sugars: 9% (maltose, melezitose) Ash: 0.17% In this example the ash would include all the minerals in honey. Ashing is also performed prior to chemical analysis by inductively coupled plasma emission spectrometry.
In April 2013, Hird, as coach, was accused of being personally injected with supplements in 2011 and 2012 that would be deemed performance enhancing if he were a player. Essendon players from 2011 and 2012 were also accused of ingesting performance enhancing supplements. As head coach, Hird was subsequently implicated. Following months of rumours and investigations, on 13 August 2013, Hird, along with the Essendon Football Club, senior assistant coach Mark Thompson, football manager Danny Corcoran and club doctor Bruce Reid, was charged by the AFL with bringing the game into disrepute in relation to the poor governance of the supplements program at the club in 2011 and 2012. The club was given 14 days to consider the charges and faced an AFL Commission hearing on 26 August 2013. On 27 August 2013, following much negotiation, Hird accepted charges that he had brought the game into disrepute and abandoned possible Supreme Court action against the AFL and its chief executive, Andrew Demetriou. He maintained that he did little wrong, but said he should have known more about the club's supplements program. He was banned from working at any AFL club in any capacity for twelve months commencing from 25 August 2013. Hird was allowed to attend Essendon matches as a spectator during this period. However, despite not being allowed to pay him for working as a coach during 2014, the club paid Hird $1 million in advance for 2014 in December 2013. A media report on 3 October 2013 said that Hird denied pleading guilty for a reduced charge as alleged by Demetriou.
== See also == Controlled Substances Act Controlled Substance Analogue Enforcement of 1986 Controlled Drugs and Substances Act Lizard Labs New chemical entity Online illicit drug vendor Operation Web Tryp Federal Analogue Act Pharmaceutical company Psychoactive Substances Act 2013 – New Zealand Psychoactive Substances Act 2016 – UK ban on all drugs based on psychoactive effect PsychonautWiki Research chemical
Sources: en.wikipedia.org
Two or more of these techniques are often combined. This can improve preservation and reduce unwanted side effects such as the denaturation of nutrients by severe heat treatments. Common combinations are salting/drying, salting/marinating, salting/smoking, drying/smoking, pasteurization/refrigeration and controlled atmosphere/refrigeration. Other process combinations are currently being developed along the multiple hurdle theory.
Metabolism of glucose produces ATP, which increases the ATP to ADP ratio. The KATP channels close when the ATP to ADP ratio rises. The closure of the KATP channels causes the outward potassium ion current to diminish, leading to inward currents of potassium ions dominating. As a result, the potential difference across the membrane becomes more positive (as potassium ions accumulate inside the cell). This change in potential difference opens the voltage-gated calcium channels, which allows calcium ions from outside the cell to move into the cell down their concentration gradient. When the calcium ions enter the cell, they cause vesicles containing insulin to move to, and fuse with, the cell surface membrane, releasing insulin by exocytosis into the pancreatic capillaries. The venous blood then eventually empties into the hepatic portal vein. In addition to the triggering pathway, the amplifying pathway can cause increased insulin secretion without a further increase in intracellular calcium levels. The amplifying pathway is modulated by byproducts of glucose metabolism along with various intracellular signaling pathways; incretin hormone signaling being one important example.
==== NMDA receptor activity ==== NMDA receptor activation is essential to producing the activity-dependent molecular changes involved in the formation of new memories. Following exposure to an enriched environment, BDNF and NR1 phosphorylation levels are upregulated simultaneously, probably because BDNF is capable of phosphorylating NR1 subunits, in addition to its many other effects. One of the primary ways BDNF can modulate NMDA receptor activity is through phosphorylation and activation of the NMDA receptor one subunit, particularly at the PKC Ser-897 site. The mechanism underlying this activity is dependent upon both ERK and PKC signaling pathways, each acting individually, and all NR1 phosphorylation activity is lost if the TrKB receptor is blocked. PI3 kinase and Akt are also essential in BDNF-induced potentiation of NMDA receptor function and inhibition of either molecule eliminated receptor BDNF can also increase NMDA receptor activity through phosphorylation of the NR2B subunit. BDNF signaling leads to the autophosphorylation of the intracellular domain of the TrkB receptor (ICD-TrkB). Upon autophosphorylation, Fyn associates with the pICD-TrkB through its Src homology domain 2 (SH2) and is phosphorylated at its Y416 site. Once activated, Fyn can bind to NR2B through its SH2 domain and mediate phosphorylation of its Tyr-1472 site. Similar studies have suggested Fyn is also capable of activating NR2A although this was not found in the hippocampus. Thus, BDNF can increase NMDA receptor activity through Fyn activation.
Repatriating the survivors of the 16 October strike on a semi-submersible to their home countries for prosecution avoids a civilian court challenge to continued detention without evidence, and a military court challenge to the legal justification for treating prisoners as unlawful combatants if they were not engaged in armed conflict.
=== Reduction of metal salts and oxides === Many metal carbonyls are prepared by reductive carbonylation. This method entails the reduction of metal halides in the presence of carbon monoxide, often at high pressures. A variety of reducing agents are employed, including copper, aluminum, hydrogen, as well as metal alkyls such as triethylaluminium. Illustrative is the formation of chromium hexacarbonyl from anhydrous chromium(III) chloride in benzene with aluminum as a reducing agent, and aluminum chloride as the catalyst:
Sources: en.wikipedia.org
Household goods (HHG) include furniture, art and similar items. Express: Very small business or personal items like envelopes are considered overnight express or express letter shipments. These shipments are rarely over a few kilograms or pounds and almost always travel in the carrier's own packaging. Express shipments almost always travel some distance by air. An envelope may go coast to coast in the United States overnight or it may take several days, depending on the service options and prices chosen by the shipper. Parcel: Larger items like small boxes are considered parcels or ground shipments. These shipments are rarely over 50 kg (110 lb), with no single piece of the shipment weighing more than about 70 kg (154 lb). Parcel shipments are always boxed, sometimes in the shipper's packaging and sometimes in carrier-provided packaging. Service levels are again variable but most ground shipments will move about 800 to 1,100 km (497 to 684 mi) per day. Depending on the package's origin, it can travel from coast to coast in the United States in about four days. Parcel shipments rarely travel by air and typically move via road and rail. Parcels represent the majority of business-to-consumer (B2C) shipments. Freight: Beyond HHG, express, and parcel shipments, movements are termed freight shipments.
=== July === July 2, 2010: Canada Twenty thousand new jobs were added to Canada's economy. The unemployment rate is expected to have stayed at 8.1%. Economists expect initiated home building was at an annual rate of 192,000 last month, up from 189,100 in May.
Reference Model of Open Distributed Processing (RM-ODP) is a reference model in computer science, which provides a co-ordinating framework for the standardization of open distributed processing (ODP). It supports distribution, interworking, platform and technology independence, and portability, together with an enterprise architecture framework for the specification of ODP systems. RM-ODP, also named ITU-T Rec. X.901-X.904 and ISO/IEC 10746, is a joint effort by the International Organization for Standardization (ISO), the International Electrotechnical Commission (IEC) and the Telecommunication Standardization Sector (ITU-T).
== Genetics == Contrary to bacteria and fungi, most plant metabolic pathways are not grouped into biosynthetic gene clusters, but instead are scattered as individual genes. Some exceptions have been discovered: steroidal glycoalkaloids in Solanum, polyketides in Pooideae, benzoxazinoids in Zea mays, triterpenes in Avena sativa, Cucurbitaceae, Arabidopsis, and momilactone diterpenes in Oryza sativa.
Sources: en.wikipedia.org
No. It is a laboratory-made peptide, while the natural hormone is alpha-melanocyte-stimulating hormone, a longer peptide produced by the pituitary gland and by skin cells. Melanotan-2 mimics only a short active region of that hormone and contains non-natural residues such as D-phenylalanine.
No approved regulatory indication exists in major markets. An approval exists for a different peptide, afamelanotide, which is used for a rare photosensitivity disorder called erythropoietic protoporphyria. Melanotan-2 itself remains a research compound with no cleared clinical role.
Melanocortin-1 receptors on melanocytes are the receptor most closely linked to pigment production. The peptide is not selective, however, and also activates melanocortin-3, melanocortin-4, and melanocortin-5 receptors. That lack of selectivity is the usual explanation offered for both its range of observed effects and its off-target effects.
Major regulatory agencies have not approved it for any indication. Some countries permit it only under prescription frameworks, while others classify it as a controlled substance.