This is a working overview of afamelanotide, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-08-27. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
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.
| 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.
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.
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.
Nevertheless, he added that the repeal will not affect the recognition of "traditional familial and societal norms," including how marriage is defined, leaving the legal status of same-sex marriage unchanged for the time, although the possibility of civil unions was not officially ruled out. Lee described this as a compromise between the conservative (and often religious) and progressive elements of Singaporean society to prevent further political fracturing. The law was officially repealed on 3 January 2023. Pink Dot SG, an event held in support of the LGBT community, has drawn thousands of people annually since 2009 with increasing attendance. According to a survey conducted by the Institute of Policy Studies in 2019, Singaporean society has become more liberal on LGBT rights. In the survey, more than 20% of people said that sexual relations between adults of the same sex were not wrong at all or not wrong most of the time, up from 10% in 2013. The survey found that 27% felt the same way about same-sex marriage (an increase from 15% in 2013) and 30% did so about same-sex couples adopting a child (an increase from 24% in 2013). Pimps often traffic women from neighbouring countries such as China, Malaysia and Vietnam at their brothels as well as rented apartments and hostels for higher profit margins when they get a cut from customers. In response, amendments were made to the Women's Charter by the government in 2019 to legislate more serious punishments for traffickers, including imprisonment of up to seven years and a fine of S$100,000.
== Contraindications == Methylergometrine is contraindicated in patients with hypertension and pre-eclampsia. It is also contraindicated in HIV positive patients taking protease inhibitors, delavirdine, and efavirenz (which is also an agonist at the 5-HT2A–mGlu2 receptor protomer and increases the chances of a patient experiencing hallucinations during methylergometrine therapy).
In July 2024, Lyme Disease Vaccine Reached Completion of the Primary Series In July 2024, Pfizer and Flagship Pioneering announced an "Innovation Supply Chain" partnership to co-develop 10 drug candidates. Each party committed $50 million upfront, leveraging Flagship's ecosystem of over 40 startups to align with Pfizer's priorities. Pfizer will fund the selected programs and has the option to license or acquire assets, with potential success milestones and royalties reaching up to $700 million per commercialized drug. Two programs, focused on obesity and cardiovascular diseases, have already been initiated. In July 2024, Pfizer advanced its obesity treatment research through the development of danuglipron, an oral glucagon-like peptide-1 (GLP-1) receptor agonist: In August 2024, Pfizer introduced PfizerForAll, a digital platform designed to streamline access to healthcare and wellness resources in the United States. In October 2024, Pfizer announced positive results from phase 3 TALAPRO-2 trial of Talzenna in combination with Xtandi in patients with mCRPC. In October 2024, Pfizer announced a partnership with the Ignition AI Accelerator, a collaborative initiative by Nvidia, Tribe, and Digital Industry Singapore (DISG). The collaboration aims using artificial intelligence to expedite drug discovery and development processes, improve operational efficiency, and streamline stakeholder engagement. The initiative also focuses on optimizing manufacturing processes, including improving yields and reducing cycle times.
=== Genotoxicity and mutagenicity === Mutation studies in prokaryotes and eukaryotes show that ractopamine is not mutagenic. However, the results of several in vitro studies, including chromosome aberration tests in human lymphocytes, are positive. The positive genotoxic results are explained with limited evidence to be due to a secondary auto-oxidative mechanism from ractopamine-catechol-producing reactive intermediates.
If the mutation occurs in the region of the gene where transcriptional machinery binds to the protein, the mutation can affect the way in which transcription factors bind to the protein. The mechanisms of transcription bind to a protein through recognition of short nucleotide sequences. A mutation in this region may alter these sequences and, thus, change the way the transcription factors bind to the protein. Mutations in this region can affect the efficiency of gene transcription, which controls both the levels of mRNA and overall protein levels.
Sources: en.wikipedia.org
which is 50 times bigger than the force on the left piston. The difference between force and pressure is important: the additional pressure is exerted against the entire area of the larger piston. Since there is 50 times the area, 50 times as much force is exerted on the larger piston. Thus, the larger piston will support a 50 N load – fifty times the load on the smaller piston. Forces can be multiplied using such a device. One newton input produces 50 newtons output. By further increasing the area of the larger piston (or reducing the area of the smaller piston), forces can be multiplied, in principle, by any amount. Pascal's principle underlies the operation of the hydraulic press. The hydraulic press does not violate energy conservation, because a decrease in distance moved compensates for the increase in force. When the small piston is moved downward 100 centimeters, the large piston will be raised only one-fiftieth of this, or 2 centimeters. The input force multiplied by the distance moved by the smaller piston is equal to the output force multiplied by the distance moved by the larger piston; this is one more example of a simple machine operating on the same principle as a mechanical lever. A typical application of Pascal's principle for gases and liquids is the automobile lift seen in many service stations (the hydraulic jack). Increased air pressure produced by an air compressor is transmitted through the air to the surface of oil in an underground reservoir. The oil, in turn, transmits the pressure to a piston, which lifts the automobile.
== Shelf life == The shelf life of rations depends on the type and purpose, including how long the ration is intended to be used or kept until logistics and steady food supplies can reach the front lines. Per NATO standardization, the shelf life of a field ration from the time of delivery must be at least 24 months at a storage temperature of 25 °C; individual rations are designed to be used for a period of 30 days, after which fresh food should be given and medical screening should be conducted for nutritional deficiencies.
In a clinical trial, the group that does not receive the new treatment being studied. This group is compared to the group that receives the new treatment, to see if the new treatment works. (NCI) The standard by which experimental observations are evaluated. In many clinical trials, one group of patients will be given an experimental drug or treatment, while the control group is given either a standard treatment for the illness or a placebo (NLM) Controlled clinical trial
===== PI 88788 ===== The vast majority of cultivars in the US have soybean cyst nematode resistance (SCN resistance), but rely on only one breeding line (PI 88788) as their sole source of resistance. (The resistance genes provided by PI 88788, Peking, and PI 90763 were characterized in 1997.) As a result, for example, in 2012 only 18 cultivars out of 807 recommended by the Iowa State University Extension had any ancestry outside of PI 88788. By 2020 the situation was still about the same: Of 849 there were 810 with some ancestry from PI 88788, 35 from Peking, and only 2 from PI 89772. (On the question of exclusively PI 88788 ancestry, that number was not available for 2020.) That was speculated to be in 2012—and was clearly by 2020—producing SCN populations that are virulent on PI 88788.
Sources: en.wikipedia.org
The division mobilized to the Clermont area in Argonne, just west of Verdun, starting on 24 September, stationed there to act as a reserve for the US First Army. On 3 October, Major General George B. Duncan, commander of the 77th Division, relieved William Burnham of his duties and took over as commander of the 82nd. On the night of 6 October 1918, the 164th Brigade relieved troops of the 28th Division, which were holding the front line from south of Fléville to La Forge, along the eastern bank of the Aire River. On 7 October, the 82nd Division, minus the 163rd Brigade, which remained in reserve, attacked the northeastern edge of the Argonne Forest, taking "Hill 223" in the process. The division's right flank entered the commune of Cornay but later withdrew southeast. The division's left flank took the high ground northwest of Châtel-Chéhéry. On 9 October, the division's left flank advanced to form a line along the French pylons on the road to the Belgian city of la Louvière. Throughout October, the division advanced north-east along the Aire (Aisne) river. On 10 October, it relieved troops of the 1st Division in Ardennes at Fléville and Sommerance. The 82nd Division then relaunched an attack on Cornay and the Belgian city of Enghien, successfully re-establishing the front there. On 11 October, the right flank of the division took the high ground north of the Rance river while the left flank continued to advance along the Aire. The next day, the 42nd Division relieved the 82nd's troops in Sommerance.
Legal proceedings involving UCC, the United States and Indian governments, local Bhopal authorities, and the disaster victims started immediately after the catastrophe. The Indian Government passed the Bhopal Gas Leak Act in March 1985, allowing the Government of India to act as the legal representative for victims of the disaster, leading to the beginning of legal proceedings. Initial lawsuits were generated in the United States federal court system. On 17 April 1985, Federal District court judge John F. Keenan (overseeing one lawsuit) suggested that "'fundamental human decency' required Union Carbide to provide between $5 million and $10 million to immediately help the injured" and suggested the money could be quickly distributed through the International Red Cross. UCC, on the notion that doing so did not constitute an admission of liability and the figure could be credited toward any future settlement or judgement, offered a $5 million relief fund two days later. The Indian government turned down the offer. In March 1986, UCC proposed a settlement figure, endorsed by plaintiffs' U.S. attorneys, of $350 million that would, according to the company, "generate a fund for Bhopal victims of between $500–600 million over 20 years". In May, litigation was transferred from the United States to Indian courts by a U.S. District Court ruling. Following an appeal of this decision, the U.S. Court of Appeals affirmed the transfer in November 1986, judging that UCIL was a "a separate and independent legal entity, managed and operated exclusively by Indian citizens in India".
=== Matrix === The matrix system has a drug layer of a semisolid matrix containing a drug solution or suspension. The adhesive layer in this patch surrounds the drug layer, partially overlaying it. The release rate is determined by the physical properties of the matrix. Also known as a monolithic device. Limited research indicates that it may be possible to cut some matrix patches to provide lower doses, provided the cut part not immediately used is stored at cool temperatures.
== Disadvantages == Limited to protein immunogens (not useful for non-protein based antigens such as bacterial polysaccharides) Potential for atypical processing of bacterial and parasite proteins Potential when using nasal spray administration of plasmid DNA nanoparticles to transfect non-target cells, such as brain cells Cross-contamination when manufacturing different types of live vaccines in same facility
The AAA pathway involves the condensation of α-ketoglutarate and acetyl-CoA via the intermediate AAA for the synthesis of L-lysine. This pathway has been shown to be present in several yeast species, as well as protists and higher fungi. It has also been reported that an alternative variant of the AAA route has been found in Thermus thermophilus and Pyrococcus horikoshii, which could indicate that this pathway is more widely spread in prokaryotes than originally proposed. The first and rate-limiting step in the AAA pathway is the condensation reaction between acetyl-CoA and α‑ketoglutarate catalysed by homocitrate-synthase (HCS) (E.C 2.3.3.14) to give the intermediate homocitryl‑CoA, which is hydrolysed by the same enzyme to produce homocitrate. Homocitrate is enzymatically dehydrated by homoaconitase (HAc) (E.C 4.2.1.36) to yield cis-homoaconitate. HAc then catalyses a second reaction in which cis-homoaconitate undergoes rehydration to produce homoisocitrate. The resulting product undergoes an oxidative decarboxylation by homoisocitrate dehydrogenase (HIDH) (E.C 1.1.1.87) to yield α‑ketoadipate. AAA is then formed via a pyridoxal 5′-phosphate (PLP)-dependent aminotransferase (PLP-AT) (E.C 2.6.1.39), using glutamate as the amino donor. From this point on, the AAA pathway varies with [something is missing here ? -> at the very least, section header! ] on the kingdom.
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 seven-amino-acid peptide modeled on alpha-melanocyte-stimulating hormone. It carries two non-natural substitutions and a cyclic bridge that increase its stability relative to the natural hormone. It circulates as a research chemical and is not an approved medicine.