A practical reference on afamelanotide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-04-06. Anything still debated is marked as such rather than presented as settled.
Melanotan-2 is handled in the laboratory as a lyophilised powder that dissolves readily in water, dimethyl sulfoxide and dimethylformamide, with limited solubility in ethanol. Stock solutions prepared in an organic solvent often precipitate when diluted into aqueous buffer, so gradual dilution with mixing is standard practice. The peptide carries a tryptophan residue and a histidine residue, both sensitive to oxidation and to alkaline conditions. Working solutions are therefore kept near neutral to slightly acidic pH, protected from light, and consumed within the same working session whenever that is practical.
Solid peptide kept dry at minus twenty degrees Celsius, shielded from light and moisture, is generally considered stable for extended periods. Solutions are divided into single-use aliquots and held at minus twenty or minus eighty degrees Celsius, because repeated freeze-thaw cycles promote aggregation and loss of material to container surfaces. Hydrolysis of the backbone and oxidation of tryptophan are the principal degradation routes in aqueous solution, and both accelerate at ambient temperature. Hygroscopic uptake after a vial is opened can also shift the actual mass weighed, which affects any concentration calculated from it.
Routine characterisation relies on reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, using a C18 column and a water-acetonitrile gradient containing trifluoroacetic acid. Electrospray ionisation mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidised by-products that co-elute poorly. Sequence and stereochemistry require additional work, such as peptide mapping or amino acid analysis, because a chromatographic purity figure alone does not distinguish a diastereomer from the target peptide. Independent testing of research-grade material frequently shows measured content below the stated label, so a certificate of analysis is best read together with the method that produced it.
Receptor binding at MC1R on melanocytes raises intracellular cyclic AMP and increases expression of tyrosinase and related enzymes. The downstream result is greater synthesis of eumelanin, the dark pigment, without ultraviolet exposure acting as the trigger. The compound is not selective, however, and also engages MC3R, MC4R and MC5R, which are expressed in the central nervous system and elsewhere. That lack of selectivity is the explanation usually offered for effects reported outside pigmentation, including appetite suppression and nausea. Selectivity remains a central theme in comparative studies of related peptides.
Human data remain limited and mostly short-term. Reports describe small trials and observational accounts rather than large controlled studies, so questions about dose-response relationships and long-term effects on melanocytes stay open. Whether repeated exposure alters naevus behaviour is not settled in the published record. Researchers also note that self-administered use outside clinical settings makes actual exposure difficult to quantify. Statements about efficacy and safety should therefore be read as preliminary rather than established.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised material may be hygroscopic |
| Solubility class | Soluble in water, DMSO and DMF | Dilution into aqueous buffer can cause precipitation |
| Storage of solid | Minus 20 degrees C, desiccated, dark | Aliquot to limit repeated opening of the vial |
| Storage of solution | Minus 20 to minus 80 degrees C, aliquoted | Avoid repeated freeze-thaw cycles |
| Identity method | Reversed-phase HPLC with mass spectrometry | Retention time and mass are checked together |
Freeze-dried melanotan-2 is normally kept as a desiccated powder at minus twenty degrees Celsius or lower, shielded from light and moisture. Peptides of this size degrade through hydrolysis, oxidation and deamidation, and each pathway accelerates as temperature and water activity rise. Repeated freeze-thaw cycles promote aggregation and loss of material, so aliquoting a stock solution before freezing is standard laboratory practice. Once dissolved, the solution is markedly less stable than the powder. In laboratory work, solutions are generally refrigerated and used within days rather than kept for months.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, which separates the target peptide from truncated or oxidised impurities. Mass spectrometry, most often coupled to liquid chromatography, confirms molecular mass and detects substitutions that chromatography alone may miss. Amino acid analysis and peptide mapping supply additional structural evidence, while nuclear magnetic resonance is reserved for full structural confirmation. Laboratories that examine samples sold online report wide variation in actual content, with some vials containing little or none of the labelled material.
Melanotan-2 appears on the World Anti-Doping Agency prohibited list within the peptide hormone class, and several national regulators treat it as an unapproved prescription substance. Some countries restrict importation or sale for personal use. Because the compound is widely traded as a research chemical, the practical legal picture differs between jurisdictions and shifts over time. Human safety data covering long periods are limited, and whether repeated pigmentation changes carry any lasting risk to melanocytes remains an open question.
Melanotan-2 is a synthetic linear peptide built from seven amino acids arranged in a short chain. Its sequence is commonly written as Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH2, which includes a modified N-terminus and an amidated C-terminus. The molecule belongs to the melanocortin family and acts as a receptor agonist. Structural features such as the D-phenylalanine residue and the Nle substitution are associated with increased stability against enzymatic degradation relative to the natural parent peptide.
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.
Melanotan II holds no marketing authorisation from the Food and Drug Administration, the European Medicines Agency, the UK Medicines and Healthcare products Regulatory Agency or Australia's Therapeutic Goods Administration. Products sold under that name are treated as unapproved new drugs, and their sale or import is prohibited in several jurisdictions. Other countries classify the peptide as a prescription-only medicine or place it among controlled substances, so the legal position changes with the destination market. No pharmacopoeial monograph supplies an official specification, because the material is not a licensed pharmaceutical. Consequently, products offered online are not manufactured to a shared public standard.
The peer-reviewed record is dominated by small early-phase studies, case reports and pharmacovigilance summaries rather than large randomised trials. Papers typically examine tanning response, receptor selectivity or patterns of reported adverse events. Many note that participants obtained the peptide outside a clinical setting, which limits verification of composition and administered amount. Reported events vary widely, and causality is frequently unclear because the identity and purity of self-sourced material are unknown. Open questions include whether repeated melanocortin receptor stimulation produces cumulative effects, and how often label claims match actual content.
Species Calotropis acia Buch.-Ham. - India Calotropis gigantea (L.) Dryand. - China, Indian Subcontinent, Southeast Asia Calotropis procera (Aiton) Dryand. - China, Indian Subcontinent, Southeast Asia, Middle East, North Africa formerly included Calotropis sussuela, synonym of Hoya imperialis
Microscope slides: Specimens can be mounted on microscope slides for short-term storage, however, there is a greater risk of rapid deterioration from contracting, darkening, or crystallizing specimens. Slides should be checked on an annual basis to check the condition of preserved specimens. Desiccants and freeze-drying: Silica gel or freeze-drying methods can be applied to specimens that require preservation of the shape of a delicate organ such as a flower. Disadvantages of this technique are that the specimen is especially fragile and lacks support. Acid-free tissue is often used for storage.
==== Image analysis ==== Both art-historical digital image processing and analog techniques have been applied to the shroud images. In 1976 scientists used imaging equipment from the American National Aeronautics and Space Administration (NASA) to analyze a photograph of the Shroud image and decoded the shroud image into a three-dimensional image. The optical physicist and former STURP member John Dee German has noted that it is not difficult to make a photograph which has 3D qualities. If the object being photographed is lit from the front, and a non-reflective "fog" of some sort exists between the camera and the object, then less light will reach and reflect back from the portions of the object that are farther from the lens, thus creating a contrast which is dependent on distance. The front image on the shroud is 1.95 metres (6 ft 5 in) long, and is not exactly the same size as the rear image, which is 2.02 metres (6 ft 8 in) long. Analysis of the images found them to be compatible with the shroud having been used to wrap a body 1.75 metres (5 ft 9 in) long. The image could be compared to oshiguma, the making of face-prints as an artform, in Japan. Furthermore, the subject's physical appearance corresponds to Byzantine iconography. The Shroud cloth is composed of threads of a nominal diameter of 0.15 mm, woven with fibers of linen with a diameter of about 10-20 μm. The Shroud image is a faint and superficial image caused by a translucent and discontinuous yellow discoloration of the fibers.
Pizza Hut also offers a chicken wing menu. The menu was launched in 2003 under the WingStreet branding in existing Pizza Hut franchises, with the plan to turn WingStreet into a standalone chain. Yum! Brands predicted aggressive growth, adding more than 4,000 locations by 2010. In 2012, the company opened a standalone pilot store in Denton, Texas. The store was unsuccessful and closed the following year.
Sources: en.wikipedia.org
Specifically, carboxamides and oximes can be converted to nitriles by dehydration (elimination of water). Numerous reagents and methodologies are available for this transformation. Methods for nitrile synthesis via dehydration of nitroalkanes have also been described. Phosphorus pentoxide, known since the mid-19th century, is a classical reagent for amide dehydration. Amides can also be dehydrated using trivalent phosphorus reagents such as phosphorus trichloride or triphenyl phosphite; as well as diethyl chlorophosphate, thionyl chloride, or phosgene. In the presence of specific palladium complexes or other suitable catalysts, acetonitrile can function as a dehydrating agent, converting an amide into a nitrile while being transformed into acetamide. Similarly, dichloroacetonitrile may be employed. Related systems utilize iron(II) chloride tetrahydrate, zinc trifluoromethanesulfonate, or uranyl nitrate as catalysts in combination with N-methyl-N-trimethylsilyltrifluoroacetamide as the dehydrating reagent. Carboxylic acid amides can also be dehydrated using a system comprising triphenylphosphane, iodine, and 4-methylmorpholine. Another approach involves high-temperature dehydration (220–240 °C) in hexamethylphosphoramide (HMPA). Dehydration of primary amides with zinc chloride under microwaves is reversible. In aqueous acetonitrile, an amide can be converted to a nitrile; however, in a water–tetrahydrofuran system with added acetamide, the reverse conversion of nitrile to amide occurs.
== Importance in winemaking == Assimilable nitrogen is an essential nutrient needed by wine yeast in order to fully complete fermentation with a minimum amount of undesirable by-products (such as compounds like hydrogen sulfide that can create off odors) created. Over the course of a fermentation, yeast may use up to a 1000 mg/L of amino acids though often far less than amount is needed. Yeast can store amino acids in intracellular vacuoles and then later either use them directly, incorporating them into proteins, or break them down and use their carbon and nitrogen components separately. In the absence of nitrogen, yeast will begin to shut down and die off. Some strains will begin breaking down sulfur containing amino acids like cysteine and methionine releasing a sulfur atom that can combine with hydrogen to produce hydrogen sulfide (H2S) which can impart rotten egg odors to the wine. However, there is not a direct correlation between YAN levels and hydrogen sulfide production since H2S can be produced by yeast even in the presence of abundant nitrogen but with instead other vital nutrients (such as the vitamin pantothenic acid) lacking. There are even some strains of S. cerevisiae that produce H2S as a response to having too much available nitrogen (particularly too much glutamic acid and alanine). This is why a prophylactic approach of indiscriminately adding nitrogen supplementation to every fermentation may not have the desired results of preventing H2S.
The bergamot essential oil is particularly subject to adulteration being an essential oil produced in relatively small quantities. Generally adulteration is to "cut" the oil, i.e. adding distilled essences of poor quality and low cost, for example of bitter orange and bergamot mint and/or mixtures of terpenes, natural or synthetic, or "reconstruct" the essence from synthetic chemicals, coloring it with chlorophyll. Worldwide, each year, around three thousand tonnes of declared essence of bergamot are marketed, while the genuine essence of bergamot produced annually amounts to no more than one hundred tons. Natural source analysis based on the Carbon-14 method can identify adulterated essences by detecting synthetic chemicals manufactured from petroleum that are used to mimic the chemical profile of bergamot oil and other essential oils. Gas chromatography with columns having a chiral stationary phase allows analyzing mixtures of enantiomers. The analysis of the enantiomeric distribution of various compounds, such as linalyl acetate and linalool, allows the characterization of the bergamot oil according to the manufacturing process and allows for the detection of possible adulteration. The combined use of isotope ratio mass spectrometry and SNIF-NMR (Site-Specific Natural Isotope Fractionation-Nuclear Magnetic Resonance) allows discovering adulteration otherwise undetectable even allowing for the identification of the geographical origin of the essential oil.
Sources: en.wikipedia.org
== Bioinformatics resources and tools == Databases and computational tools for mimotopes have been an important part of phage display study. Databases, programs and web servers have been widely used to exclude target-unrelated peptides, characterize small molecules-protein interactions and map protein-protein interactions. Users can use three dimensional structure of a protein and the peptides selected from phage display experiment to map conformational epitopes. Some of the fast and efficient computational methods are available online.
Mixed by producer Paul Northfield and engineered by Terry Brown, it is a three-disc live album featuring recorded performances from the band's Counterparts, Test For Echo, and A Farewell to Kings tours, dedicated to the memory of Selena and Jacqueline. After a time of grief and recovery, and while visiting longtime Rush photographer Andrew MacNaughton in Los Angeles, Peart was introduced to his future wife, photographer Carrie Nuttall, and they married on September 9, 2000. In 2001, Peart decided to return to Rush.
Durham County Council is the local authority for the unitary authority area of County Durham in North East England. The unitary authority area is smaller than the ceremonial county of Durham, which additionally includes Darlington, Hartlepool, and part of Stockton-on-Tees. The council has its headquarters at County Hall in the city of Durham, and consists of 98 councillors. It is a member of the North East Combined Authority. Since the 2025 Durham County Council election the council has been under the majority control of Reform UK. The chair of the council is Robbie Rodis, and the leader is Andrew Husband. The council had a Labour Party majority from 1925 until 2021, when it fell into no overall control. Between 1889 and 1974 Durham consisted of an administrative county governed by a county council, and several county boroughs with their own councils. In 1974, as part of reforms to local government in England, Durham was reconstituted as a two-tier non-metropolitan county governed by a county council and eight district councils. In 1997, the Borough of Darlington was reconstituted as a unitary authority, making it independent of the county council. Durham County Council was itself reconstituted as a unitary authority in 2009, when the seven remaining district councils were abolished and the county council took on their responsibilities.
Sources: en.wikipedia.org
Purity is normally stated as an area percentage from high-performance liquid chromatography, for example ninety-five or ninety-eight percent. That figure describes the proportion of ultraviolet-absorbing material eluting as the main peak. It says nothing about water content, counterions, residual solvents or mass fraction of the peptide itself.
Peptides are commonly isolated as acetate or trifluoroacetate salts, and the counterion contributes to total mass. Two vials with identical peptide content can therefore differ in weight and in measured response. Residual trifluoroacetate is also relevant in cell-based work because it can influence membrane behaviour.
Degradation products are often closely related to the parent molecule, making them hard to resolve with a single method. Counterion variability adds a further source of scatter between laboratories. Because no pharmacopoeial monograph exists for melanotan-2, groups rely on method-specific validation rather than a shared reference standard.
It is a synthetic cyclic heptapeptide and a non-selective melanocortin receptor agonist. Structurally it is modelled on alpha-melanocyte-stimulating hormone, a peptide that occurs naturally in the body.