The short version of melanotan II fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-03-27 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.
Melanotan II binds several melanocortin receptor subtypes rather than a single target. MC1R on melanocytes drives melanin synthesis, while MC3R and MC4R participate in energy balance, appetite, and sexual response pathways. This lack of selectivity explains why reported effects extend beyond skin darkening. Substitutions at positions four and seven, including norleucine and D-phenylalanine, increase potency and resistance to peptidases. Understanding which receptor mediates which effect remains an active area of investigation.
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.
| 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 |
Identity testing for a synthetic peptide relies on several complementary methods. Reversed-phase high-performance liquid chromatography separates the target from related impurities and reports purity as a percentage of total peak area. Mass spectrometry confirms molecular mass and can reveal deletions or truncations. Amino acid analysis and peptide mapping provide sequence-level confirmation, while counter-ion content and residual solvents are measured separately. A purity figure alone does not establish identity, so a complete dataset combines chromatographic and spectrometric evidence.
Lyophilized peptide powder is generally stored frozen, protected from light and moisture. Tryptophan residues are susceptible to oxidation, and the lactam bridge can hydrolyze under strongly acidic or basic conditions. Solutions prepared for laboratory work degrade faster than dry powder, and repeated freeze-thaw cycles accelerate loss. Common practice is to aliquot solutions before freezing and to avoid alkaline buffers. Reported stability windows vary with concentration, buffer, and temperature, so exact shelf lives are method-specific rather than universal.
Regulatory status differs by country, and in many places supplying the compound for human consumption is unlawful. Vendors frequently label material as intended for research use only, a designation that shifts stated purpose but does not create a legal pathway for personal use. Certificates of analysis accompanying such products vary widely in detail and provenance. Third-party testing exists but is voluntary, and results are rarely linked to a specific lot in a publicly verifiable way.
Melanotan-2, also written Melanotan II, is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, and the lactam bridge between the aspartate and lysine side chains constrains the peptide into a ring. This structural change increases receptor affinity and metabolic stability relative to the native hormone. The compound was created in the 1980s as a research tool for studying pigmentation biology.
Melanocytes are the pigment-producing cells of the skin, and they carry melanocortin-1 receptors on their surface. When the receptor is activated, cyclic adenosine monophosphate rises inside the cell and raises the activity of enzymes such as tyrosinase, which increases melanin output. Melanotan-2 binds melanocortin-1 receptors in vitro and in animal models, and this binding is generally described as the basis for the tanning effect. Other receptors account for different effects: melanocortin-4 receptors contribute to appetite and erectile signalling, while melanocortin-3 and melanocortin-5 receptors contribute to energy balance and exocrine function.
Early published reports described melanotan-2 as a tanning agent without sun protection, which means darkening is not the same as protection against ultraviolet radiation. Later studies explored the peptide in erectile dysfunction, hemorrhagic shock, and some skin conditions. No regulator in the United States or Europe has approved it for clinical use. Many products labelled melanotan-2 are sold without approval and their identity and purity are unverified. Its long-term safety in humans remains an open question.
=== Autoimmune diseases === Problems posed by the differences in the human and rodent immune systems have been overcome using a few strategies, so as to enable researchers to study autoimmune disorders using humanized models. As a result, the use of humanized mouse models has extended to various areas of immunology and disease research. For instance, humanized mice have been utilized to study human-tropic pathogens, liver cancer models, and the comparison of mouse models to human diseases NSG mice engrafted with PBMCs and administered with myelin antigens in Freund's adjuvant, and antigen-pulsed autologous dendritic cells have been used to study multiple sclerosis. Similarly, NSG mice engrafted with hematopoietic stem cells and administered with pristane have been used for studying lupus erythematosus. Furthermore, NOG mice engrafted with PBMCs has been used to study mechanisms of allografts rejection in vivo. The development of humanized mouse models has significantly advanced the study of autoimmune disorders and various areas of immunology and disease research. These models have provided a platform for investigating human diseases, immune responses, and therapeutic interventions, bridging the gap between human and rodent immune systems and offering valuable insights into disease pathogenesis and potential therapeutic strategies.
=== Resistance === Development of bacterial resistance under therapy is a frequent occurrence and makes fosfomycin unsuitable for sustained therapy of severe infections. Mutations that inactivate the nonessential glycerophosphate transporter render bacteria resistant to fosfomycin. Still, fosfomycin can be used to treat MRSA bacteremia. Prescribing fosfomycin together with at least another active drug reduces the risk of developing bacterial resistance. Fosfomycin acts synergistically with many other antibiotics, including aminoglycosides, carbapenems, cephalosporins, daptomycin and oritavancin. Enzymes conferring resistance to fosfomycin have also been identified and are encoded both chromosomally and on plasmids. Three related fosfomycin resistance enzymes (named FosA, FosB, and FosX) are members of the glyoxalase superfamily. These enzymes function by nucleophilic attack on carbon 1 of fosfomycin, which opens the epoxide ring and renders the drug ineffective. The enzymes differ by the identity of the nucleophile used in the reaction: glutathione for FosA, bacillithiol for FosB, and water for FosX. In general, FosA and FosX enzymes are produced by Gram-negative bacteria, whereas FosB is produced by Gram-positive bacteria. FosC uses ATP and adds a phosphate group to fosfomycin, thus altering its properties and making the drug ineffective.
A β-helix is formed from repeating structural units consisting of two or three short β-strands linked by short loops. These units "stack" atop one another in a helical fashion so that successive repetitions of the same strand hydrogen-bond with each other in a parallel orientation. See the β-helix article for further information. In lefthanded β-helices, the strands themselves are quite straight and untwisted; the resulting helical surfaces are nearly flat, forming a regular triangular prism shape, as shown for the 1QRE archaeal carbonic anhydrase at right. Other examples are the lipid A synthesis enzyme LpxA and insect antifreeze proteins with a regular array of Thr sidechains on one face that mimic the structure of ice.
Once the relative volume occupied by PMN cells at the junctional epithelium reaches 60%, the junctional epithelium is unable to adhere to the root surface of the tooth and separates from it while the apical portion of the junctional epithelium migrates apically. This process, known as apical migration, results in the increase of the sulcular epithelium lining of this ‘false pocket’ (pseudopocket).
Sources: en.wikipedia.org
=== Tumor detection === In cancer research, colloidal gold can be used to target tumors and provide detection using SERS (surface enhanced Raman spectroscopy) in vivo. These gold nanoparticles are surrounded with Raman reporters, which provide light emission that is over 200 times brighter than quantum dots. It was found that the Raman reporters were stabilized when the nanoparticles were encapsulated with a thiol-modified polyethylene glycol coat. This allows for compatibility and circulation in vivo. To specifically target tumor cells, the polyethylenegylated gold particles are conjugated with an antibody (or an antibody fragment such as scFv), against, e.g. epidermal growth factor receptor, which is sometimes overexpressed in cells of certain cancer types. Using SERS, these pegylated gold nanoparticles can then detect the location of the tumor. Gold nanoparticles accumulate in tumors, due to the leakiness of tumor vasculature, and can be used as contrast agents for enhanced imaging in a time-resolved optical tomography system using short-pulse lasers for skin cancer detection in mouse model. It is found that intravenously administered spherical gold nanoparticles broadened the temporal profile of reflected optical signals and enhanced the contrast between surrounding normal tissue and tumors.
On 26 September 1937, the acting British district commissioner of Galilee, Lewis Yelland Andrews, was assassinated in Nazareth. Four days later Britain outlawed the Arab Higher Committee, and began to arrest its members. On 1 October 1937, the National Bloc, the Reform Party and the Istiqlal Party were dissolved. Yaqub al-Ghusayn, Al-Khalidi and Ahmed Hilmi Pasha were arrested and then deported. Jamal al-Husayni escaped to Syria, as did Abd al-Qadir al-Husayni. Amin al-Husayni managed to escape arrest, but was removed from the presidency of the Supreme Muslim Council. The committee was banned by the Mandate administration and three members (and two other Palestinian leaders) were deported to the Seychelles and the others moved into voluntary exile in neighbouring countries. Awni Abd al-Hadi, who was out of the country at the time, was not allowed to return. The National Defence Party, which had withdrawn from the AHC soon after its formation, was not outlawed, and Raghib al-Nashashibi was not pursued by the British.
=== Diagnostics === There is interest in its use in wearable technology. Sweat can be sampled and sensed non-invasively and continuously using electronic tattoos, bands, or patches. However, sweat as a diagnostic fluid presents numerous challenges as well, such as very small sample volumes and filtration (dilution) of larger-sized hydrophilic analytes. Currently the only major commercial application for sweat diagnostics is for infant cystic fibrosis testing based on sweat chloride concentrations.
Sources: en.wikipedia.org
=== Apoptosis === One of the most studied roles of ceramide pertains to its function as a proapoptotic molecule. Apoptosis, or Type I programmed cell death, is essential for the maintenance of normal cellular homeostasis and is an important physiological response to many forms of cellular stress. Ceramide accumulation has been found following treatment of cells with a number of apoptotic agents, including ionizing radiation, UV light, TNF-alpha, and chemotherapeutic agents. This suggests a role for ceramide in the biological responses of all these agents. Because of its apoptosis-inducing effects in cancer cells, ceramide has been termed the "tumor suppressor lipid". Several studies have attempted to define further the specific role of ceramide in the events of cell death and some evidence suggests ceramide functions upstream of the mitochondria in inducing apoptosis. However, owing to the conflicting and variable nature of studies into the role of ceramide in apoptosis, the mechanism by which this lipid regulates apoptosis remains elusive.
=== Genetic predisposition === The genetic locus most significantly associated with Sjögren’s is the major histocompatibility complex/human leukocyte antigen (MHC/HLA) region, as demonstrated by the preliminary results of the first genome-wide association study. This study included data from a discovery cohort of 395 patients of European ancestry with primary Sjögren's disease, and 1,975 healthy control individuals, and from a replication study that comprised 1,234 cases and 4,779 healthy controls. Associations with polymorphisms located at six independent loci were also detected; IRF5, STAT4, BLK, IL12A, TNIP1, and CXCR5. This also suggested the activation of the innate immune system, notably through the IFN system, B-cell activation through CXCR5-directed recruitment to lymphoid follicles and B-cell receptor (BCR) activation involving BLK, and T-cell activation owing to HLA susceptibility and the IL-12-IFN-γ-axis. Patients of different ethnic origins carry different HLA-susceptibility alleles, of which HLA-DR and HLA-DQ are involved in the pathogenesis of Sjögren's disease. For example, patients from Northern and Western Europe and North America show a high prevalence of B8, DRw52, and DR3 genes. HLA class II alleles are associated with the presence of specific subsets of autoantibodies, rather than with the disease itself. Autoantibodies refer to the loss of B-cell tolerance leading to the production of antibodies directed against diverse organ-specific and organ-nonspecific antigens.
August 3 – Allan Nascimento, 34, mixed martial artist (UFC). August 18 – Glória Menezes, 91, actress. September 9 – Jackson Nascimento, 102, football player (Athletico Paranaense, Corinthians) and manager (Athletico Paranaense). September 14 – Aracy Amaral, 96, art historian and curator, director of the Pinacoteca do Estado de São Paulo (1975–1979) and the Museum of Contemporary Art, University of São Paulo (1982–1986). September 15 – Amelinha Teles, 81, journalist and political activist. Paulo César Martin, 62, journalist and radio host (Folha de S.Paulo, TV Globo, Conrad Editora). September 22 – Rick Sollo, 59, singer-songwriter (Rick & Renner) and Sertanejo music producer. September 26 – Pedro Antônio Marchetti Fedalto, 100, Roman Catholic prelate, auxiliary bishop (1966–1970) and archbishop (1970–2004) of Curitiba.
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.
No regulator in a major market has approved it for human use. It appears in research settings and in products marketed outside pharmacy channels. Legal status for personal possession varies by country.