If you have been reading about cyclic heptapeptide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2025-10-26. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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-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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms differ |
| Molecular weight | Approximately 1024 g/mol | Calculated for the free base |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water and polar solvents | Poorly soluble in non-polar solvents |
| Typical storage | -20 degrees Celsius, dry, protected from light | Refers to the solid form |
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.
Hydroxypethidine (Bemidone) is an opioid analgesic that is an analogue of the more commonly used pethidine (meperidine). Hydroxypethidine is slightly more potent than meperidine as an analgesic, 1.5x meperidine in potency, and it also has NMDA antagonist properties like its close relative ketobemidone. Hydroxypethidine has similar effects to other opioids, and produces analgesia, sedation and euphoria. Side effects can include itching, nausea and potentially serious respiratory depression which can be life-threatening. Hydroxypethidine is under international control under the Single Convention on Narcotic Drugs 1961 and therefore controlled like morphine in most countries; in the United States it is a Schedule I Narcotic controlled substance with an ACSCN of 9627 and a 2014 annual aggregate manufacturing quota of 2 grams. The salt in use is the hydrochloride, with a free base conversion ratio of 0.878.
==== Endocrine and metabolic disorders ==== Several endocrine conditions can cause proximal muscle weakness and laboratory abnormalities that mimic inflammatory myopathy. This includes thyroid issues (hypothyroidism or hyperthyroidism), where your thyroid hormones are either too high or too low. Also, it’s important to consider Cushing syndrome and acromegaly.
== See also == Thomas Graham (chemist), the founder of dialysis and father of colloid chemistry Dialysis tubing List of dialysis providers in the United States Vitamin and mineral management for dialysis Nephrology Hepatorenal syndrome
On 27 April 1954, Queen Elizabeth II and her husband Prince Philip, Duke of Edinburgh visited the colony as part of their first Commonwealth tour. They were greeted by Governor of Aden Tom Hickinbotham and travelled to an enclosure to watch a military parade which included the RAF, Aden Protectorate Levies, Armed Police, Government Guards, the Hadhrami Bedouin Legion, and Somaliland Scouts. The visit saw Aden hold its first and only knighthood ceremony in which local leader Sayyid Abubakr bin Shaikh Al-Kaff was knighted whilst kneeling on a chair instead of bowing due to his Muslim faith. The Queen also knighted Claude Pelly, who was Commander-in-Chief of the Royal Air Force in the Middle East. A bronze plaque marks the foundation stone Elizabeth II laid for Al Jumhuriyah hospital during the visit. The hospital which was originally named after her until the end of British rule in 1967 was bombed by the Houthi movement in 2015, but remains open due to a UAE-funded restoration project.
Sources: en.wikipedia.org
This article incorporates text by Laura J. Cobb, Changhan Lee, Jialin Xiao, Kelvin Yen, Richard G. Wong, Hiromi K. Nakamura, Hemal H. Mehta, Qinglei Gao, Carmel Ashur, Derek M. Huffman, Junxiang Wan, Radhika Muzumdar, Nir Barzilai, and Pinchas Cohen2 available under the CC BY 4.0 license.
Cipepofol (INNTooltip International Nonproprietary Name, USANTooltip United States Adopted Name), also known as ciprofol or by its developmental code name HSK3486, sold under the brand name Cypsedo, is a general anesthetic related to propofol which is used for anesthesia and sedation. The drug is used by intravenous infusion. A short-acting and highly selective GABAA positive allosteric modulator, ciprofol is 4 to 6 times more potent than other phenol derivatives such as propofol or fospropofol. In May 2026, cipepofol was approved for medical use in the United States. Manufactured by Haisco Pharmaceutical Group, ciprofol underwent phase I and II trials in Australia and China.
A report by the Public Accounts Committee finds that only 10% of the money promised to reduce inequality under the Levelling Up scheme had actually been spent. The Animal Welfare (Import of Dogs, Cats and Ferrets) Bill, introduced as a private member's bill, passes its first reading in the House of Commons after securing the backing of the UK government. The bill aims to ban the import of puppies, kittens and ferrets under the age of six months into the UK. Apple agrees to pay a £385m settlement on a lawsuit led by Norfolk County Council, which was started over allegations Apple CEO Tim Cook defrauded shareholders in a pension company administered by the Council by covering up lower demand for iPhones in China. 16 March – Vaughan Gething is elected to lead Welsh Labour, and will become First Minister of Wales. He will be Wales's first black leader, and the first black person to lead a country in Europe. With Gething's win it means that three of the four governments in the UK will have non-white leaders. A group calling itself the South Devon Primary, which aims to unseat Conservative MPs in South Devon at the next election, chooses Liberal Democrat Caroline Voaden as a candidate for one of its constituencies. Traditional Unionist Voice leader Jim Allister announces a formal "partnership" with Reform UK at the next general election. 17 March – Transport Secretary Mark Harper tells the BBC that the Conservative Party welcomes members "whatever their race".
The two substrates of this enzyme are 3-hydroxypropionic acid and oxidised nicotinamide adenine dinucleotide (NAD+). Its products are 3-oxopropanoic acid, reduced NADH, and a proton. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 3-hydroxypropanoate:NAD+ oxidoreductase. This enzyme participates in beta-alanine metabolism and propanoate metabolism.
On 1 December 1978, the Health and Safety Executive announced their intention to prosecute the university for breach of safety legislation. The case was heard in October 1979 at Birmingham Magistrates' Court. Although the source of infection was traced, the mode and cause of transmission was not. Evidence presented by several internationally recognised experts, including Kevin McCarthy, Allan Watt Downie and Keith R. Dumbell, showed that airborne transmission from the laboratory to the telephone room where Parker was supposedly infected was highly improbable. The experts calculated that it would require 53,700 litres (11,812 imp gal) of virus fluid to have been aspirated (meaning, in this context, removed by suction of fluid and cells through a needle) and it would take 20,000 years for one particle to travel to the telephone room at the rate the fluid was aspirated. It was additionally found that although the Shooter Inquiry noted the poor state of the duct sealing in the laboratory, this was caused after the outbreak by engineers fumigating the laboratory and ducts. The university was found not guilty of causing Parker's death.
Sources: en.wikipedia.org
Any protein that can be split into two parts and reconstituted non-covalently to form a functional protein may be used in a PCA. The two fragments however have low affinity for each other and must be brought together by other interacting proteins fused to them (often called "bait" and "prey" since the bait protein can be used to identify a prey protein, see figure). The protein that produces a detectable readout is called "reporter". Usually enzymes which confer resistance to nutrient deprivation or antibiotics, such as dihydrofolate reductase or beta-lactamase respectively, or proteins that give colorimetric or fluorescent signals are used as reporters. When fluorescent proteins are reconstituted the PCA is called Bimolecular fluorescence complementation assay. The following proteins have been used in split protein PCAs:
== Distribution == The labeled [18F]FDG compound has a relatively short shelf life which is determined largely by the physical decay of fluorine-18 with a half-life of 109.8 minutes, or slightly less than two hours. Still, this half-life is sufficiently long to allow shipping the compound to remote PET scanning facilities, in contrast to other medical radioisotopes like carbon-11 with a half-life of ~20 minutes. Due to transport regulations for radioactive compounds, delivery is normally done by specially licensed road transport, but means of transport may also include dedicated small commercial jet services. Transport by air allows expanding the distribution area around a [18F]FDG production site to deliver the compound to PET scanning centres within a 1–3-hour flight time. Recently, on-site cyclotrons with integral shielding and portable chemistry stations for making [18F]FDG have accompanied PET scanners to remote hospitals. This technology holds some promise in the future, for replacing some of the scramble to transport [18F]FDG from site of manufacture to site of use.
This local processing is especially important in image processing, where the early CNN layers typically identify simple local patterns such as edges and curves, with subsequent layers detecting more complex patterns like textures, and eventually whole objects.
=== Background === Mogo is a sentient and living planet. When it is desired, its affiliation with the Corps is shown with foliage arranged into a green band, marked with the standard Green Lantern Corps lantern symbol, circling Mogo's equator. In its early appearances, Mogo is not a social Green Lantern and its interactions with the rest of the DC universe are not well documented. It avoids announcing its presence, preferring to represent itself using pseudonymous holograms. In Mogo's first appearance, it is explained that the planet-sized Mogo's gravitational field would wreak havoc on any other planet it would try to "visit", hence Mogo "doesn't socialize". At the same time, Mogo has allowed alien races to live on its surface and has been willing to change its conditions to suit them. When Parallax, possessing Hal Jordan, destroys the power battery on Oa and kills the Guardians, Mogo loses contact with the Green Lantern energy that helped sustain him. Without energy, Mogo loses consciousness and drifts through Sector 1014 until he is discovered by a nomadic alien race, who strip Mogo of his natural resources and pollute his environment. Mogo's body reacts instinctively, creating constructs to hinder the aliens' efforts to exploit his resources. Mogo is finally rescued by Kyle Rayner, who uses his power ring to reawaken him. With the restoration of the Green Lantern Corps, Mogo has taken on the role of a training and recreation planet for his fellow Green Lanterns. Soranik Natu, Kyle Rayner, and other Lanterns have traveled to his sector to ask for his counsel.
Sources: en.wikipedia.org
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.
Both are synthetic analogues derived from the same parent hormone. Reference descriptions usually characterise afamelanotide as more selective for the MC1R subtype, whereas melanotan-2 is reported to interact with a wider range of melanocortin receptors.
Early studies explored melanocortin signalling and pigmentation, which later led to informal use of the label tanning peptide. That label is not a regulatory category and does not imply approved status for any purpose.
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.