This is a working overview of cyclic heptapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-08-21 and is reviewed periodically as new material appears.
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.
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.
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.
| 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 |
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 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.
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.
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.
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.
The compound was developed in the late 1980s and early 1990s by academic researchers investigating melanocortin signaling and pigmentation. Early work explored whether synthetic analogs could reproduce effects of the natural hormone under controlled conditions. The molecule never advanced through the full regulatory pathway required for approval as a medicine. From the mid-2000s onward it appeared in unregulated consumer markets, often distributed through informal channels. That gap between research origins and commercial availability shapes how the compound is discussed today.
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.
== Energy metabolism == Some obligate anaerobes use fermentation, while others use anaerobic respiration. Aerotolerant organisms are strictly fermentative. In the presence of oxygen, facultative anaerobes use aerobic respiration. In the absence of oxygen, some facultative anaerobes use fermentation, while others may use anaerobic respiration.
The defense along the Vistula took place from August 1944 until the renewed Soviet offensive in January 1945. By January 1945, the 4th Panzer Army was holding static defensive positions on Hitler's direct orders and during the lull in the fighting it had created a defensive zone in southern Poland. On 1 January 1945, the 4th Panzer Army, then under Army Group A, had a total strength of 133,474 men spread across seven infantry divisions (68th, 72nd, 88th, 168th, 291st, 304th, 342nd), two Panzergrenadier divisions (10th, 20th), two panzer divisions (16th, 17th), two autonomous brigades, an autonomous regiment and several autonomous artillery detachments. With its manpower, it was the largest single contributor to Army Group A's overall manpower of 400,556. Unknown to the Wehrmacht, the Soviet command planned to saturate the entire defensive zone with artillery bombardment. The Red Army began their Vistula–Oder Offensive on January 17, quickly encircling the LVI Panzer Corps and destroying half of all armoured forces concentrated with the 4th Panzer Army. The commander of the LVI Corps, General Johannes Block, was killed in action on 26 January. The remnants of the army retreated along the entire front before re-grouping on the western bank of the Oder River in February 1945. The Red Army halted its offensive in February 1945. The 3rd Panzer Army was tasked to halt the Soviets in the north, while the 9th Army was guarding against the Soviets in the centre.
==== Celanese synthesis ==== An alternative industrial synthesis developed at Celanese involves firstly direct acylation of phenol with acetic anhydride in the presence of hydrogen fluoride to give a methyl ketone, then the conversion of the ketone with hydroxylamine to a ketoxime, and finally the acid-catalysed Beckmann rearrangement of the oxime to the amide in the para-acetylaminophenol product.
Hundreds of thousands of tons of toxic debris containing more than 2,500 contaminants and known carcinogens were spread across Lower Manhattan when the towers collapsed. Exposure to the toxins in the debris is alleged to have contributed to fatal or debilitating illnesses among people who were at Ground Zero. The Bush administration ordered the Environmental Protection Agency (EPA) to issue reassuring statements regarding air quality in the aftermath of the attacks, citing national security, but the EPA did not determine that air quality had returned to pre–September 11 levels until June 2002. Health effects extended to residents, students, and office workers in Lower Manhattan and nearby Chinatown. Several deaths have been linked to the toxic dust, and victims' names were included in the World Trade Center memorial. An estimated 18,000 people have developed illnesses as a result of the toxic dust. There is also scientific speculation that exposure to toxic products in the air may have negative effects on fetal development. A study of rescue workers released in April 2010 found that all those studied had impaired lung function. Years after the attacks, legal disputes over the costs of related illnesses were still in the court system. In 2006, a federal judge rejected New York City's refusal to pay for health costs for rescue workers, allowing for the possibility of suits against the city. Government officials have been faulted for urging the public to return to lower Manhattan in the weeks shortly after the attacks.
More recently, expression and immunogenicity have been further increased in model systems by the use of the cytomegalovirus (CMV) immediate early promoter, and a retroviral cis-acting transcriptional element. Additional modifications to improve expression rates include the insertion of enhancer sequences, synthetic introns, adenovirus tripartite leader (TPL) sequences and modifications to the polyadenylation and transcriptional termination sequences. An example of DNA vaccine plasmid is pVAC, which uses SV40 promoter. Structural instability phenomena are of particular concern for plasmid manufacture, DNA vaccination and gene therapy. Accessory regions pertaining to the plasmid backbone may engage in a wide range of structural instability phenomena. Well-known catalysts of genetic instability include direct, inverted and tandem repeats, which are conspicuous in many commercially available cloning and expression vectors. Therefore, the reduction or complete elimination of extraneous noncoding backbone sequences would pointedly reduce the propensity for such events to take place and consequently the overall plasmid's recombinogenic potential.
Sources: en.wikipedia.org
==== Elimination ==== Gabapentin, pregabalin, Baclofen and phenibut are all eliminated renally in the urine. They all have relatively short elimination half-lives, with reported values of 5.0 to 7.0 hours, 6.3 hours, 2.0 to 5.0 hours and 5.3 hours, respectively. Similarly, the terminal half-life of gabapentin enacarbil IR (as active gabapentin) is short at approximately 4.5 to 6.5 hours. Because of its short elimination half-life, gabapentin must be administered 3 to 4 times per day to maintain therapeutic levels. Similarly, pregabalin has been given 2 to 3 times per day in clinical studies. Phenibut, also, is taken 3 times per day. Conversely, gabapentin enacarbil is taken twice a day and gabapentin XR (brand name Gralise) is taken once a day.
Beverages (B) Freeze dried drink mixes (coffee or tea) or flavored drinks (lemonade or orange drink) are provided in vacuum-sealed beverage pouches. Coffee and tea may have powdered cream and/or sugar added depending on personal taste preferences. Empty beverage retort pouches are provided for drinking water.
== Release == Library of Ruina was initially released for Windows via Steam's early access program on May 15, 2020, before being fully released for Windows and Xbox One on August 10, 2021. Versions for Nintendo Switch and PlayStation 4 were made available by publisher Arc System Works on April 25, 2024.
=== Clinical social work === Social workers provide a variety of services, generally concerned with social problems, their causes, and their solutions. With specific training, clinical social workers may also provide psychological counseling (in the US and Canada), in addition to more traditional social work.
Sources: en.wikipedia.org
Structural proteins confer stiffness and rigidity to otherwise-fluid biological components. Most structural proteins are fibrous proteins; for example, collagen and elastin are critical components of connective tissue such as cartilage, and keratin is found in hard or filamentous structures such as hair, nails, feathers, hooves, and some animal shells. Some globular proteins can play structural functions, for example, actin and tubulin are globular and soluble as monomers, but polymerize to form long, stiff fibers that make up the cytoskeleton, which allows the cell to maintain its shape and size. Other proteins that serve structural functions are motor proteins such as myosin, kinesin, and dynein, which are capable of generating mechanical forces. These proteins are crucial for cellular motility of single celled organisms and the sperm of many multicellular organisms which reproduce sexually. They generate the forces exerted by contracting muscles and play essential roles in intracellular transport.
In recent years, the clinical understanding of the FDA's "black box" warning has evolved to focus on the balance between medication risks and the risks of untreated depression. While the 2004 and 2006 warnings regarding increased suicidal ideation in children and young adults (under 25) remain, long-term data published through 2024 suggests that these warnings may have led to an unintended decline in depression treatment, which some studies correlate with an increase in suicide deaths among adolescents. Statistical meta-analyses updated in 2022 confirm that while the risk of suicidal thoughts in youth on antidepressants like fluoxetine is approximately twice that of a placebo (4% vs 2%), there remains no statistically significant increase in completed suicides across dozens of pediatric trials. Furthermore, recent data continues to show a protective effect in older populations; for adults aged 65 and older, antidepressant use is associated with a statistically significant decrease in suicidality. Regarding specific treatments, research published between 2021 and 2023 reinforces that fluoxetine is most effective and carries the lowest risk of adverse behavioral events when paired with psychotherapy. A 2022 meta-analysis found that combination therapy (medication plus CBT) resulted in a lower incidence of suicidal events compared to fluoxetine alone.
=== Saddiction and hiatus (2024–present) === At the beginning of February 2024, Hangman's Chair returned to perform at Le Mondial du Tatouage – Tattoo Planetarium, which brought together 500 tattoo artists from around the world, at Paris' Grande halle de la Villette. In October 2024, the band released the single "2 am Thoughts" and its music video, taken from the upcoming seventh album, Saddiction. "2 am Thoughts" features a guest appearance from Raven van Dorst of Dool. The music video follows Nackphouminh, the original singer of Hangman's Chair, through a day in his life, three years after he adopted a healthier lifestyle combining sport and spiritual exploration. He is the author of the video's closing line. The band went on a European tour with Dool in October 2024. They released the single "Kowloon Lights" in November. Saddiction was released on 14 February 2025 through Nuclear Blast Records, with the group's lineup remaining unchanged: Chanut, Thépegnier, Hanvic, and Toufouti. A Loner and Saddiction would be part of a new trilogy. The album entered at number 13 on the French SNEP–SCPP Rock and Metal Chart compiled by the OCC. Mathieu David of Rolling Stone France wrote that Hangman's Chair "continues to weave their simultaneously heavy and hovering ambiences amidst mysterious urban landscapes". He added that while A Loner "hovered at 10,000 feet in an ethereal cloud, Saddiction brings back the riffs, not without reminding the harshest ambiences of Banlieue Triste". Other singles followed: "In Disguise", "Healed?", and "The Worst is Yet to Come".
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.
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.