This is a working overview of afamelanotide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-11-09 and is reviewed periodically as new material appears.
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.
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
Melanotan II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
| 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 |
This type of patients' skeletal maturation should be closely and regularly monitored. Both male and female patients who have the following medical conditions must not start a treatment with HCG Pubergen, Pregnyl: (1) Hypersensitivity to this drug or to any of its main ingredients. (2) Known or possible androgen-dependent tumors for example male breast carcinoma or prostatic carcinoma.
In vivo, chymotrypsin is a proteolytic enzyme (serine protease) acting in the digestive systems of many organisms. It facilitates the cleavage of peptide bonds by a hydrolysis reaction, which despite being thermodynamically favorable, occurs extremely slowly in the absence of a catalyst. The main substrates of chymotrypsin are peptide bonds in which the amino acid N-terminal to the bond is a tryptophan, tyrosine, phenylalanine, or leucine. Like many proteases, chymotrypsin also hydrolyses amide bonds in vitro, a virtue that enabled the use of substrate analogs such as N-acetyl-L-phenylalanine p-nitrophenyl amide for enzyme assays. Chymotrypsin cleaves peptide bonds by attacking the unreactive carbonyl group with a powerful nucleophile, the serine 195 residue located in the active site of the enzyme, which briefly becomes covalently bonded to the substrate, forming an enzyme-substrate intermediate. Along with histidine 57 and aspartic acid 102, this serine residue constitutes the catalytic triad of the active site. These findings rely on inhibition assays and the study of the kinetics of cleavage of the aforementioned substrate, exploiting the fact that the enzyme-substrate intermediate p-nitrophenolate has a yellow colour, enabling measurement of its concentration by measuring light absorbance at 410 nm. Chymotrypsin catalysis of the hydrolysis of a protein substrate (in red) is performed in two steps.
==== Spain ==== The term "Donuts" was already trademarked by one of the largest Spanish bakery firms, Panrico, so the company was born as a joint venture between Dunkin' Donuts' then-parent Allied Domecq and Panrico (only Spanish shareholders, representing 50%) in order to use the brand name "Dunkin' Donuts". In 2007, after Dunkin' Donuts bought out Panrico's 50% share, the stores were rebranded to "Dunkin' Coffee". As of 2017, there are 59 Dunkin' Coffee locations in Spain, the majority of which are in Barcelona, Madrid, and Málaga. Their slogan, "Juntos es mejor", translates to "Together is better".
Copper-catalyzed allylic substitutions are chemical reactions with unique regioselectivity compared to other transition-metal-catalyzed allylic substitutions such as the Tsuji-Trost reaction. They involve copper catalysts and "hard" carbon nucleophiles. The mechanism of copper-catalyzed allylic substitutions involves the coordination of copper to the olefin, oxidative addition and reductive elimination. Enantioselective versions of these reactions have been used in the synthesis of complex molecules, such as (R)-(-)-sporochnol and (S)-(-)-zearalenone.
13 March – Five people are taken to hospital for treatment after a bus crashes into a high rise block of flats in Paisley, Glasgow. 14 March – The Scottish Parliament Corporate Body finds Michael Matheson in breach of the Ministerial Code over his £11,000 iPad bill. Mountaineer Anna Wells becomes the first woman to reach the top of all of Scotland's 282 Munros in one winter season. 15 March – Following trial and conviction at the High Court in Glasgow, double murderer Peter Duffy is sentenced to at least 30 years in prison for the murder of his wife, Emma Baillie, and brother, John-Paul Duffy, in separate incidents in Coatbridge in 2022. 17 March – HMP Kilmarnock becomes the first privately run prison in Scotland to pass into the ownership of the Scottish Prison Service after its contract with Serco comes to an end. 19 March – Scottish Prison Service director Allister Purdie gives evidence to the Scottish COVID-19 Inquiry, and apologises to the family of Callum Inglis, who died at Addiewell Prison during the pandemic, after his family learned of the death through word of mouth before they were told formally by prison authorities. 21 March – The Scottish Parliamentary Corporate Body confirms that members of Scottish Parliament staff will no longer be allowed to wear rainbow lanyards, or any other badge or jewellery associated with social issues, while at Holyrood. The Wildlife Management and Muirburn (Scotland) Bill passes its final vote in the Scottish Parliament.
Sources: en.wikipedia.org
NONMEM is a non-linear mixed-effects modeling software package developed by Stuart L. Beal and Lewis B. Sheiner in the late 1970s at University of California, San Francisco, and expanded by Robert Bauer at Icon PLC. Its name is an acronym for nonlinear mixed effects modeling but it is especially powerful in the context of population pharmacokinetics, pharmacometrics, and PK/PD models. NONMEM models are written in NMTRAN, a dedicated model specification language that is translated into FORTRAN, compiled on the fly and executed by a command-line script. Results are presented as text output files including tables. There are multiple interfaces to assist modelers with housekeeping of files, tracking of model development, goodness-of-fit evaluations and graphical output, such as PsN and xpose and Wings for NONMEM. Current version for NONMEM is 7.5.
Pfizer CEO Albert Bourla has said that he declined money from Operation Warp Speed to avoid government intervention, stating later that "when you get money from someone that always comes with strings. They want to see how we are going to progress, what type of moves you are going to do. They want reports. And also, I wanted to keep Pfizer out of politics, by the way." In May 2020, Pfizer began testing four different COVID-19 vaccine variations using lipid nanoparticle technology provided by Canadian biotechnology company Acuitas Therapeutics. Vaccines were injected into the first human participants in the U.S. in early May. In July 2020, Pfizer and BioNTech announced that two of the partners' four mRNA vaccine candidates had won fast track designation from the FDA. The company began Phase II-III testing on 30,000 people in the last week of July 2020 and was slated to be paid $1.95 billion for 100 million doses of the vaccine by the US government. In September 2020, Pfizer and BioNTech announced that they had completed talks with the European Commission to provide an initial 200 million vaccine doses to the EU, with the option to supply another 100 million doses at a later date. On November 9, 2020, Pfizer announced that BioNTech's COVID-19 vaccine, tested on 43,500 people, was found to be 90% effective at preventing symptomatic COVID-19. The efficacy was updated to 95% a week later, described as a "really a spectacular number" and made Pfizer and BioNTech the first companies to develop and test a working vaccine for COVID-19.
== Adverse effects == The adverse effects of fentanyl analogs are also similar to those of fentanyl itself, including itching, nausea, and severe respiratory depression, which may be life-threatening.
==== Tests for pigments ==== In October 1978 a team of scientists affiliated with STURP took 32 samples from the surface of the Shroud, using adhesive tape. Of those samples, 18 were taken from areas of the Shroud that showed a body or blood image, while 14 were taken from non-image areas. The chemical microscopist Walter McCrone, a leading expert in the forensic authentication of historical documents and works of art, examined the tapes using polarized light microscopy and other physical and chemical techniques. McCrone concluded that the Shroud's body image had been painted with a dilute pigment of red ochre (a form of iron oxide) in a collagen tempera (i.e., gelatin) medium, using a technique similar to the grisaille employed in the 14th century by Simone Martini and other European artists. McCrone also found that the "bloodstains" in the image had been highlighted with vermilion (a bright red pigment made from mercury sulfide), also in a collagen tempera medium. McCrone reported that no actual blood was present in the samples taken from the Shroud. Other members of STURP rejected McCrone's conclusions and concluded, based on their own examination of the Shroud and the tape samples, that the image on the Shroud could not be explained by the presence of pigments. Mark Anderson, who was working for McCrone, analyzed the Shroud samples. In his book, chemist Raymond Rogers states that Anderson, who was McCrone's Raman microscopy expert, concluded that the samples acted as organic material when he subjected them to the laser.
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.
No. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.