This is a working overview of alpha-MSH, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-02-07 and is reviewed periodically as new material appears.
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.
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.
== Literature == Emanuel Gil-Av, Present status of enantiomeric analysis by gas chromatography, J. Mol. Evol. 6 (1975) 131–144. Nelu Grinberg: Emanuel Gil-Av (1916–1996): A man with a legacy, In: Chirality, 1998;10(5):372. Volker Schurig: In Memoriam – Emanuel Gil-Av. In: Journal of High Resolution Chromatography 19 (1996) 462. Volker Schurig: On the Centenary of Emanuel Gil-Av, Former Professor of the Weizmann Institute of Science and Pioneer of Enantioselective Chromatography, Isr. J. Chem. 56 (2016) 890–906.
Urocanase (also known as imidazolonepropionate hydrolase or urocanate hydratase) is the enzyme (EC 4.2.1.49) that catalyzes the second step in the degradation of histidine, the hydration of urocanic acid to imidazol-4-one-5-propionic acid. Urocanase is coded for by the UROC1 gene, located on the third chromosome in humans. The protein itself is composed of 676 amino acids which then fold, producing the final product which has two identical subunits, making the enzyme a homodimer. To catalyze the hydrolysis of urocanate in the catabolic pathway of L-histidine the enzyme utilizes its two nicotinamide adenine dinucleotide (NAD+) groups. These act as electrophiles, attaching to the top carbon of the urocanate which leads to sigmatropic rearrangement of the urocanate molecule. This rearrangement allows for the addition of a water molecule, converting the urocanic acid into imidazol-4-one-5-propionic acid.
This can be applied to find the best substrates for proteolytic enzymes. The substrate is displayed on the bacterial cell surface between an affinity ligand and the scaffold, and the kinetics of substrate proteolysis is measured using FACS. Bacterial display can be used to find peptides which bind to specific cells e.g. breast cancer cells or stem cells. Displayed proteins are fluorescently tagged with GFP, so binding interactions between peptides and target cells can be seen by flow cytometry. Control samples are required in order to measure fluorescence levels in the absence of displayed peptides. Samples are also required which don’t contain displayed peptides, but contain mammalian cells and bacterial cells (including the scaffold). Vaccine delivery is a very common application of bacterial surface display. There are two types of live bacterial vaccines that can be made:
== In the environment == The long half-life of technetium-99 and its ability to form an anionic species make it (along with 129I) a major concern when considering long-term disposal of high-level radioactive waste. Many of the processes designed to remove fission products from medium-active process streams in reprocessing plants are designed to remove cationic species like caesium (e.g., 137Cs, 134Cs) and strontium (e.g., 90Sr). Hence the pertechnetate escapes through these treatment processes. Disposal options favor burial in geologically stable rock. The primary danger with such a course is that the waste is likely to come into contact with water, which could leach radioactive contamination into the environment. The natural cation-exchange capacity of soils tends to immobilize plutonium, uranium, and caesium cations. However, the anion-exchange capacity is usually much smaller, so minerals are less likely to adsorb the pertechnetate and iodide anions, leaving them mobile in the soil. For this reason, the environmental chemistry of technetium is an active area of research.
Sources: en.wikipedia.org
The heightened vigilance of the German garrison as the war entered its final phase made these operations especially hazardous, particularly as they were often attempted at extremely close quarters. On several occasions Rhodesian patrols only narrowly escaped discovery. During one action, two Rhodesian patrols catered for the possibility that Germans might be listening to their transmissions by communicating in Shona, an African language. The LRDG's last actions of the war, in April and May 1945, were to help Tito's partisans capture German-held islands off Dalmatia.
=== Adaptation === Obesity is characterized by the expansion of fat mass, through adipocyte size increase (hypertrophy) and, to a lesser extent, cell proliferation (hyperplasia). In the fatty tissue of obese individuals, there is increased production of metabolism modulators, such as glycerol, hormones, macrophage-stimulating chemokines, and pro-inflammatory cytokines, leading to the development of insulin resistance. Production of these modulators and the resulting pathogenesis of insulin resistance are probably caused by adipocytes as well as immune system macrophages that infiltrate the tissue. Fat production in adipocytes is strongly stimulated by insulin. By controlling the activity of the pyruvate dehydrogenase and the acetyl-CoA carboxylase enzymes, insulin promotes unsaturated fatty acid synthesis. It also promotes glucose uptake and induces SREBF1, which activates the transcription of genes that stimulate lipogenesis. SREBF1 (sterol regulatory element-binding transcription factor 1) is a transcription factor synthesized as an inactive precursor protein inserted into the endoplasmic reticulum (ER) membrane by two membrane-spanning helices. Also anchored in the ER membrane is SCAP (SREBF-cleavage activating protein), which binds SREBF1. The SREBF1-SCAP complex is retained in the ER membrane by INSIG1 (insulin-induced gene 1 protein). When sterol levels are depleted, INSIG1 releases SCAP and the SREBF1-SCAP complex can be sorted into transport vesicles coated by the coatomer COPII that are exported to the Golgi apparatus.
The buffer liquid between the two tubes is at a gradually rising concentration, always a bit over the incoming fluid, in this example reaching 1200 mg/L. This is regulated by the pumping action on the returning tube as will be explained immediately. The tip of the loop has the highest concentration of salt (NaCl) in the incoming tube—in the example 1199 mg/L, and in the buffer 1200 mg/L. The returning tube has active transport pumps, pumping salt out to the buffer liquid at a low difference of concentrations of up to 200 mg/L more than in the tube. Thus when opposite the 1000 mg/L in the buffer liquid, the concentration in the tube is 800 and only 200 mg/L are needed to be pumped out. But the same is true anywhere along the line, so that at exit of the loop also only 200 mg/L need to be pumped. In effect, this can be seen as a gradually multiplying effect—hence the name of the phenomena: a 'countercurrent multiplier' or the mechanism: Countercurrent multiplication, but in current engineering terms, countercurrent multiplication is any process where only slight pumping is needed, due to the constant small difference of concentration or heat along the process, gradually raising to its maximum. There is no need for a buffer liquid, if the desired effect is receiving a high concentration at the output pipe.
Sources: en.wikipedia.org
The Constitution of Canada is the supreme law of the country and consists of written text and unwritten conventions. The Constitution Act, 1867 (known as the British North America Act, 1867 prior to 1982), affirmed governance based on parliamentary precedent and divided powers between the federal and provincial governments. The Statute of Westminster, 1931, granted full autonomy, and the Constitution Act, 1982, ended all legislative ties to Britain, as well as adding a constitutional amending formula and the Canadian Charter of Rights and Freedoms. The Charter guarantees basic rights and freedoms that usually cannot be overridden by any government; a notwithstanding clause allows Parliament and the provincial legislatures to override certain sections of the Charter for a period of five years.
== Function == The WNT gene family consists of structurally related genes that encode secreted signaling proteins. These proteins have been implicated in oncogenesis and in several developmental processes, including regulation of cell fate and patterning during embryogenesis. This gene is a member of the WNT gene family. It encodes a protein showing 99% amino acid identity to the mouse Wnt7A protein. This gene not only guides the development of the anterior-posterior axis in the female reproductive tract but also plays a critical role in uterine smooth muscle pattering and maintenance of adult uterine function. It is also responsive to changes in the levels of sex steroid hormone in the female reproductive tract. Decreased expression of this gene in human uterine leiomyoma is found to be inversely associated with the expression of estrogen receptor alpha.
Jungermann K, Thauer RK, Leimenstoll G, Decker K (1973). "Function of reduced pyridine nucleotide-ferredoxin oxidoreductases in saccharolytic Clostridia". Biochim. Biophys. Acta. 305 (2): 268–80. doi:10.1016/0005-2728(73)90175-8. PMID 4147457.
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.