The short version of cyclic heptapeptide fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-07-19. Anything still debated is marked as such rather than presented as settled.
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.
Structurally, Melanotan-2 retains the core recognition motif of alpha-melanocyte-stimulating hormone while adding a lactam bridge that links two side chains and constrains the molecule into a ring. This modification lowers susceptibility to enzymatic degradation. The compound acts as an agonist at melanocortin receptors, particularly subtypes associated with melanin production. Because the same receptor family influences several physiological processes, researchers note that its activity is not confined to pigmentation alone. Receptor selectivity continues to be examined in published studies.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Synthetic cyclic heptapeptide |
| Molecular mass | Approximately 1024 g/mol | Depends on counter-ion content |
| Appearance | White to off-white powder | Commonly supplied as a lyophilised solid |
| Solubility | Freely soluble in water | Also dissolves in common aqueous buffers |
| Typical storage | -20 degrees Celsius, desiccated | Protect from light and repeated freeze-thaw |
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.
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.
Solid peptide material is generally stable when kept cold and dry. Common practice is storage at -20 degrees Celsius or lower, with desiccant and protection from light. Repeated freeze-thaw cycles and exposure to moisture are associated with degradation, aggregation, or loss of material. Once dissolved, stability depends on solvent, concentration, and temperature, and solutions are usually treated as short-lived unless stability data support longer periods. Handling notes typically emphasise minimising time at ambient temperature.
Identity and purity are assessed with chromatographic and mass spectrometric techniques. Reversed-phase high-performance liquid chromatography separates the target peptide from related impurities and degradation products, and the resulting retention time is compared against a reference standard. Mass spectrometry, often coupled to liquid chromatography, confirms molecular mass. Amino acid analysis or peptide mapping can provide additional sequence-level confirmation when required. Results are only as reliable as the reference materials used alongside them.
Benninghoven graduated from the University of Cologne in 1961 where he worked with Fritz Kirchner (1896–1967) and completed his habilitation in surface physics in Cologne two years later. He first worked as professor in Cologne from 1965 to 1973 until he moved to a full professor position in experimental physics at the University of Münster in 1972. He worked on static secondary ion mass spectrometry (SIMS) and its applications, and developed SIMS instruments. In 1989 he co-founded IonTOF, a company that became a world-leader in TOF-SIMS instrumentation. He has written over 300 scientific articles and several books on the topic of SIMS, many of which have become reference works on SIMS. For his work, he has received the Technology Transfer prize (German Ministry of Education and Research) and the 1984 Gaede-Langmuir Prize (American Vacuum Society) for the development of concepts and instrumentation in static secondary ion mass spectrometry and the demonstration of its usefulness in manifold applications. In 1990 he shared the Fritz-Pregl-Medaille of the Austrian Society of Analytical Chemistry with Wilhelm Simon. From 1977 to 1983, he was president of the German Vacuum Society (part of the German Physical Society).
== Nitrogen-13 == Nitrogen-13 (13N) has a half-life of a little under ten minutes. It is produced in the atmosphere when gamma rays (for example from lightning) knock neutrons out of nitrogen-14. 13N decays to 13C, emitting a positron. The positron quickly annihilates with an electron, producing two gamma rays of about 511 keV. After a lightning bolt, this gamma radiation dies down with a half-life of 10 minutes, but these low-energy gamma rays go on average only about 90 metres through the air, so they may only be detected for a minute or so as the "cloud" of 13N and 15O floats by, carried by the wind. Nitrogen-13 plays a significant role in the CNO cycle, which is the dominant source of energy in main sequence stars more massive than 1.5 times the mass of the Sun. Nitrogen-13 is used in positron emission tomography in the form of 13N-labelled ammonia, for example for myocardial perfusion imaging. It can be produced with a medical cyclotron, using a target of pure water with a trace amount of ethanol. The reactants are oxygen-16 (present as H2O) and a proton, and the products are nitrogen-13 and an alpha particle (helium-4):
== Medical use == Methaqualone's sedative-hypnotic properties were first identified in 1955. It gained popularity during the 1960s and 1970s for the treatment of insomnia, and as a general sedative and muscle relaxant. However, due to its abuse potential, it was eventually withdrawn from medical use. The drug was classified as pregnancy category D, meaning there was evidence of risk to the human fetus, and it was not recommended during pregnancy. Like other GABAergic substances, prolonged use of methaqualone can lead to drug tolerance, physical dependence, and withdrawal symptoms upon cessation.
=== Filming === Filming began in March 2019 with Glen Winter directing the pilot. Christopher Manley and Scott Peck were directors of photography on the series. Filming occurred throughout the Atlanta metropolitan area, including: Marietta, Virginia–Highland, Duluth, Lithia Springs, Dallas, Marietta Square, West End, Westlake High School, the Atlanta Center for Medical Research, Campbell Middle School, Paulding County, Smyrna, Arbor Place Mall, Vinings, Mableton, and Douglas County High School. Walter Garcia served as the series' stunt coordinator and second-unit director. He was hired to help Stargirl's staff "have a personality and be alive when she fights with it". The series continued to film in Atlanta for the second season, with filming beginning by October 28, 2020.
=== Timber === Blue gum timber is yellow-brown, fairly heavy, with an interlocked grain, and is difficult to season. It has poor timber quality due to growth stress problems, but can be used in construction, fence posts and poles.
Sources: en.wikipedia.org
The extreme lateral part of the ventromedial nucleus of the hypothalamus is responsible for the control of food intake. Stimulation of this area causes increased food intake. Bilateral lesion of this area causes complete cessation of food intake. Medial parts of the nucleus have a controlling effect on the lateral part. Bilateral lesion of the medial part of the ventromedial nucleus causes hyperphagia and obesity of the animal. Further lesion of the lateral part of the ventromedial nucleus in the same animal produces complete cessation of food intake. There are different hypotheses related to this regulation:
== Music == A musicologist, disciple and collaborator of Dom Prosper Guéranger, Dom Pothier contributed to the reconstitution, the restoration and the renewal of the Gregorian chant, a form of monophonic, unaccompanied sacred song of the Roman Catholic Church. Besides being the composer of many Gregorian songs (Officium Defunctorum, 1887) and the writer of a huge number of articles, Dom Pothier was also the head and editor of the Revue du Chant Grégorien (1892–1914) - supervising the publication of several works (Hymnes, Christmas office, Antifonario, Cantus mariales) -, the founder of the Paléographie Musicale publication for the dissemination of medieval liturgical manuscripts, and the author of a new edition of the choir books based on manuscripts of the Gregorian chant and of several studies on the plainchant, including Les mélodies grégoriennes d'après la tradition (Gregorian Melodies According to the Tradition), 1880, his chief work which became the standard work on the subject. Dom Pothier was appointed president of the newly created Pontifical Commission on the Vatican Edition of the Gregorian Liturgical Books by Pope Pius X in 1904. As chairman of this commission for the reconstitution of the music of the Roman Catholic Mass, Dom Pothier lived in Rome from 1904 till 1913. His Liber Gradualis, 1883, marked the beginning of a reform in liturgical chant and was used as a basis for the Gradual Vatican which was published, under his responsibility, in 1908.
=== Natural neurostimulation === In 2024, the theory of Natural Neurostimulation was introduced, opening the way to neurostimulation techniques which emulate, in neurological treatment, natural processes that appear during pregnancy. This notion was established by Prof Igor Val Danilov and his colleagues from Latvian universities. Latvian scientists claim that natural neurostimulation provides positive neuroplasticity, balancing the patient's nervous system in a case of systematic use of this sort of neurostimulation, emulating the natural process that causes mitochondrial and cognitive stress under similar environment. They provided evidence of the therapeutic effect of the complex impact of electromagnetic fields and acoustic waves, along with cognitive load, scaled based on the parameters of the physical interaction between mother and fetus.
As the proliferation of aristocratic families throughout the French kingdom limited the prospects of most heirs, young knights were encouraged to seek land and riches beyond their homeland, with Normandy becoming a major source of such adventurers. Many Normans of Italy, France and England eventually served as avid Crusaders soldiers under the Italo-Norman prince Bohemund I of Antioch and the Angevin-Norman king Richard the Lion-Heart, one of the more famous and illustrious Kings of England.
Sources: en.wikipedia.org
They bind to the tubulin molecules in S-phase and prevent proper microtubule formation required for M-phase. Taxanes are natural and semi-synthetic drugs. The first drug of their class, paclitaxel, was originally extracted from Taxus brevifolia, the Pacific yew. Now this drug and another in this class, docetaxel, are produced semi-synthetically from a chemical found in the bark of another yew tree, Taxus baccata. Podophyllotoxin is an antineoplastic lignan obtained primarily from the American mayapple (Podophyllum peltatum) and Himalayan mayapple (Sinopodophyllum hexandrum). It has anti-microtubule activity, and its mechanism is similar to that of vinca alkaloids in that they bind to tubulin, inhibiting microtubule formation. Podophyllotoxin is used to produce two other drugs with different mechanisms of action: etoposide and teniposide.
=== Effect of altering the peptide structure on anti-phalloidin activity === It has been shown that altering any of the proline residues reduces the inhibitory activity to zero. In addition, altering the phenylalanine residues to tyrosine or L-cyclohexylalanine also reduces the activity to zero.
The "Gatekeeper" and "Sphinkeeper" are related procedures. They are self-expandable prostheses which are implanted into the inter-sphincteric space of the anal canal using an applicator gun. Gatekeeper is a solid polyacrylonitrile (hyexpan) cylinder which expands to approximately 720% original size within 24 hours after the implantation.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide and an analogue of alpha-melanocyte-stimulating hormone. The molecule is produced by chemical synthesis rather than extracted from a biological source.
It is shorter than the native hormone and carries a cyclic constraint that improves stability. These changes raise receptor potency and slow breakdown relative to the naturally occurring peptide.
Published accounts date its development to the 1980s, when researchers were generating analogues of melanocyte-stimulating hormone. That work aimed to produce more stable compounds for studying pigmentation biology.
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.