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 2026-02-15. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Melanotan-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
The peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Melanotan II; MT-II; N-acetyl-norleucyl-cyclo[Asp-His-D-Phe-Arg-Trp-Lys] amide | Naming follows peptide convention; the numeral distinguishes it from melanotan-1 |
| Molecular formula | C50H69N15O9 | Includes the lactam bridge; no counter-ion assumed |
| Monoisotopic mass | 1023.53 Da | Free base; salts and counter-ions shift the observed value |
| Appearance | White to off-white lyophilised powder | Batch-to-batch colour variation is not itself proof of impurity |
| Typical analytical method | RP-HPLC purity determination with ESI-MS identity confirmation | Retention time alone does not establish sequence identity |
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.
Melanotan II is a synthetic peptide analog modeled on alpha-melanocyte-stimulating hormone, a naturally occurring signaling peptide involved in pigmentation. Its structure is a cyclic heptapeptide containing two non-natural substitutions, norleucine at position four and D-phenylalanine at position seven. These modifications resist enzymatic breakdown and extend the molecule's activity relative to the native hormone. The compound binds melanocortin receptors and is studied mainly as a pharmacological tool rather than a therapeutic product. It has never received approval as a medicine in any major jurisdiction.
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.
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.
Tea is mainly grown in Asia and Africa, with smaller areas in South America and around the Black and Caspian Seas. The four biggest tea-producing countries are China, India, Kenya and Sri Lanka, together representing 81% of world tea production. Smaller hubs of production include such places as São Miguel Island, Azores, in Portugal, and Guria, in Georgia. In 2022, global production of tea was 29.8 million tonnes, led by China with 49% and India with 20% of the world total. Kenya, Sri Lanka, and Turkey were secondary producers.
3 Ca(OH)2 + 6 S → 2 CaS2 + CaS2O3 + 3 H2O where the S2−2 species corresponds to the disulfide anion −S−S− (with a covalent bond between the two sulfur atoms), also present in pyrite (FeS2), a Fe(II) disulfide mineral. They also successfully controlled this reaction to achieve the conversion of elemental sulfur into a quasi-pure solution of calcium thiosulfate.
These findings were in contrast to those with the related compound 2C-B, which was potentiated by rasagiline but not by clorgiline. Circulating peak and area-under-the-curve concentrations of mescaline and TMPAA are similar with oral administration of mescaline. Conversely, levels of N-acetylmescaline (NAM) are far lower than those of mescaline or TMPAA and are thought not to be of clinical relevance. Intravenous injection of mescaline may result in less hepatic deamination than with oral administration. It has been theorized that active metabolites of mescaline might contribute to its psychoactive effects. Relatedly, TMPA and TMPE were reported in early research to show pharmacological effects in rats and rabbits with greater potency than mescaline. In addition, co-administration of mescaline with the aldehyde dehydrogenase inhibitor (ALDHI) calcium carbimide, which elevates TMPA and/or TMPE levels, has been reported to produce extreme reactions in rabbits at doses at which mescaline alone was inactive. Similarly, co-administration of TMPE with calcium carbimide markedly potentiated the effects of TMPE. However, subsequent research found that TMPA, TMPE, and NAM all failed to produce mescaline-like effects in rodent drug discrimination tests, and this was the case even when they were co-administered with calcium carbimide. Likewise, another subsequent study found that TMPE and TMPAA were both inactive in producing behavioral effects in rodents, while TMPA was much less potent than mescaline. A further study found TMPAA to be inactive in animals as well.
Yale University entered into its own licensing agreement with a private company, leading Fenn to file a lawsuit against the school in 1996. Yale countersued, requesting damages and reassignment of the patent. The two parties did not reach an out of court settlement, despite repeated attempts at mediation. In 2005, U.S. District Judge Christopher Droney ruled against Fenn, awarding Yale $545,000 in royalties and $500,000 in legal fees. Judge Droney was critical of Fenn, saying "Dr. Fenn only obtained the patent through fraud, civil theft, and breach of fiduciary duty." Evidence presented in the case indicated that Fenn had served on panels at Yale University that reviewed the institution's policy on intellectual property. A spokesperson for Yale said, "We are pleased by the result in this case and, in particular, by the court's vindication of the Yale patent policy." The ruling, and Yale's response produced a mixed reaction from some of Fenn's colleagues and former students, who wrote a letter to the Yale Daily News stating, "'Vindicating the Yale patent policy' is a poor excuse for treating a Nobel Laureate with a 68-year association with and dedicated service to the University, in such a contemptible manner."
The EP features Cantrell on lead vocals on the opening track, "Brother", and guest vocals by Ann Wilson from the band Heart, who joined Staley and Cantrell for the choruses of "Brother" and "Am I Inside". The EP also features Mark Arm of Mudhoney and Chris Cornell of Soundgarden, who shared vocals with Staley and Cantrell on the song "Right Turn", credited to "Alice Mudgarden" in the liner notes. In 1992, Alice in Chains appeared in the Cameron Crowe film Singles, performing their song "It Ain't Like That" while portraying an unnamed bar band. The band also contributed the song "Would?" to the film's soundtrack, whose video received an award for Best Video from a Film at the 1993 MTV Video Music Awards.
Sources: en.wikipedia.org
Before leaving for the Philippines, the men received further instructions and physical examinations in Camp Stoneman in Pittsburg, California, in March 1945. The men left for the Philippines on the troop ship S.S. Fairisle on March 27, 1945. The squadron arrived in Manila on April 30, 1945, and was assigned to the Fifth Air Force's 58th Fighter Group, based at Porac, Pampanga, in the Clark Field complex on the island of Luzon. Thus, the 201st Squadron of the Mexican Expeditionary Air Force, composed of about 300 men, 30 pilots and 25 U.S.-made P-47D Thunderbolt aircraft, fought against Imperial Japanese Army forces during the Battle of Luzon in pursuit of the liberation of the Philippines. The P-47D aircraft carried USAAF insignia but with Mexican colors on the tail rudder.
By the early 1990s, Roche Biomedical became one of the largest clinical laboratory networks in the United States, with 20 major laboratories and US$600 million in sales. Roche has also produced various HIV tests and antiretroviral drugs. It bought the patents for the polymerase chain reaction (PCR) technique in 1992. In 1995, the era of highly active anti-retroviral therapy (HAART) was initiated by the United States FDA's approval of Hoffman LaRoche's HIV protease inhibitor, saquinavir. Within 2 years of its approval (and that of ritonavir 4 months later) annual deaths from AIDS in the United States fell from over 50,000 to approximately 18,000. On 28 April 1995, Hoffmann-La Roche sold Roche Biomedical Laboratories, Inc. to National Health Laboratories Holdings Inc. (which then changed its name to Laboratory Corporation of America Holdings). Roche acquired Syntex in 1994, and Chugai Pharmaceuticals in 2002. In 1998, Roche acquired Corange Ltd, the parent company of Boehringer Mannheim and DePuy Manufacturing for $11 billion. Boehringer Mannheim would be rebranded as Roche Diagnostics and DePuy was sold to Johnson & Johnson. Oseltamivir an antiviral drug used to combat influenza. Roche is the only drug company authorized to manufacture the drug, which was discovered by Gilead Sciences. Roche purchased the rights to the drug in 1996, and in 2005, settled a royalty dispute, agreeing to pay Gilead tiered royalties of 14–22% of annual net sales without adjusting the payments for manufacturing costs, as had been allowed in the original licensing agreement.
== Symptoms == Soon after its discovery, scientists injected phalloidin into mice and discovered its LD50 is 2 mg/kg via IP injection. When exposed to the minimum lethal dose, it took several days for these mice to die. The only apparent side effect of phalloidin poisoning is extreme hunger. This is because phalloidin is only taken up by the liver via bile salt membrane transport proteins. Once inside the liver, phalloidin binds F-actin, preventing its depolymerization. It takes time for this process to destroy the liver cells. The kidneys can also take up phalloidin, but not as effectively as the liver. Here, phalloidin causes nephrosis.
These electrostatic forces can be large enough for material transfer between two surfaces. Most of these protocols have only been published recently and their respective advantages and disadvantages have not yet been tested against each other. It is therefore not yet clear how reliable these methods are and what level of preservation of the samples is required for them to work. ZooMS protocols can be valuable when working with cultural heritage objects as they support derivation of biological (and therefore location) data with minimal harm to the object.
Sources: en.wikipedia.org
On the other hand, those who feel he is vulgar (bastos) tend to be less satisfied. Despite keeping a low profile during his post-presidency, Duterte retained his popularity, topping four consecutive surveys conducted separately in March, June, September, and December 2023 by PUBLiCUS Asia on the voting disposition for 2025 Philippine Senate election.
=== Pharmacological treatment === Since the early 2020s, glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have become an increasingly important component of obesity treatment in Brazil. The Brazilian Health Regulatory Agency approved liraglutide for weight management in adolescents in August 2020, followed by the approval of semaglutide for expanded use in September 2023. These approvals introduced the first GLP-1 receptor agonists specifically indicated for obesity treatment in Brazil. Subsequent years saw rapid growth in the use of semaglutide and other GLP-1-based therapies, concentrated predominantly in higher-income regions. The expansion was accompanied by increasing regulatory attention regarding off-label use and counterfeit products. Brazilian clinical guidelines recommend GLP-1 receptor agonists as part of evidence-based obesity management in selected patients. A 2025 position statement issued jointly by five Brazilian medical societies reinforced the role of GLP-1 receptor agonists — including liraglutide, semaglutide, and tirzepatide - in the pharmacological management of obesity and prevention of cardiovascular complications. Internationally, semaglutide has been recognised as a significant development in obesity pharmacotherapy, with clinical trials demonstrating weight reductions of approximately 15–17% of baseline body weight in adults without type 2 diabetes.
== List of cruciferous vegetables == Extensive selective breeding has produced a large variety of cultivars, especially within the genus Brassica. One description of genetic factors involved in the breeding of Brassica species is the Triangle of U.
== International reactions == Canada: Canada's ambassador to the United Nations compared U.S. president Donald Trump's Golden Dome to a protection racket after Trump said America's northern neighbor must either pay $61 billion to join the program or could agree to annexation (in which case inclusion would be free). Ambassador Bob Rae also noted that "threats to sovereign integrity are prohibited" under the Charter of the United Nations. Earlier, Canadian minister of national defence Bill Blair had expressed a willingness for participation in the Golden Dome project. China: On 21 May 2025, Foreign Ministry spokesperson Mao Ning criticized the Golden Dome plan, claiming it "violates the principle of peaceful use of space in the Outer Space Treaty". She called on the US to "give up developing and deploying [a] global anti-missile system", which risked "turning space into a war zone". In a white paper published by the State Council Information Office in November 2025, China criticized the move towards "absolute security" and that it would "pose a serious threat to outer space security". New Zealand: New Zealand defence minister Judith Collins expressed support for the Golden Dome missile system, saying "I don't see it as an attack mechanism. It's a defence mechanism. And if people did not feel they needed to defend themselves, they wouldn't waste the money on it." Trump had earlier noted the space-based system would be "a very big part of our defense and, obviously, of our offense" and capable of striking foreign assets even before they launch.
== Conservation == Parmotrema perlatum has been identified as a species of concern in some regions due to its rarity and declining populations. In Hungary, it has been proposed for 'endangered' status in the Hungarian lichen red list, reflecting its limited distribution and the pressures it faces in its natural habitats there. Similarly, in Ukraine, the species is listed in the Red Data Book of Ukraine with the status of "Rare". Additionally, Parmotrema perlatum is red-listed in Sweden In northern North America, its NatureServe conservation status is designated as "G4", meaning "apparently secure" at the global level. In the United States, it has been assessed as secure in Kentucky and presumed extirpated in Wisconsin, while in Canada, it is considered as vulnerable in British Columbia and Ontario, and critically imperiled in New Brunswick.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, containing seven amino acids with a lactam ring and a D-configured phenylalanine residue. It is supplied as a lyophilised powder for laboratory research.
The natural hormone is a linear tridecapeptide that is rapidly degraded in circulation. Melanotan-2 is shortened, cyclised, N-terminally acetylated, and carries a D-amino acid substitution, all of which slow enzymatic breakdown.
No national medicines regulator has approved melanotan-2 for therapeutic or cosmetic use. In several jurisdictions it is treated as an unapproved prescription medicine, and its legal classification differs from country to country.
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.