Everything below concerns MC1R. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-10-22. Numbers and descriptions here follow the published literature rather than marketing material.
Regulatory status varies by jurisdiction, and the substance is frequently described as unapproved for therapeutic use. Some authorities classify it alongside prescription-only medicines or controlled categories, while others address it through general consumer protection rules. Analytical surveys have reported mismatches between label claims and measured content in products sold online, although the scope of such testing is limited. Whether these discrepancies are widespread remains an open question. Discussion in the literature therefore tends to combine chemistry, supply-chain observation and policy analysis.
The material is commonly handled as a lyophilized powder in sealed vials. The solid dissolves readily in water and in polar organic solvents, producing a clear solution after reconstitution. Light, heat and repeated freeze-thaw cycles are the concerns most often raised in handling guidance, because peptide bonds and the constrained ring can degrade. Working solutions are generally prepared fresh, and material left in solution is treated as less stable than the dry form. These properties shape how laboratories store and aliquot reference material.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry. Retention time supports identity, while the mass spectrum confirms the molecular weight of the intact peptide. Purity is frequently reported as a percentage of total peak area, a figure that depends on the wavelength, column and gradient used. Impurity profiling may also look for truncated sequences, oxidised forms and residual counterions. Amino acid analysis and peptide mapping provide orthogonal confirmation when required.
The peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
Melanotan-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Typically supplied as a lyophilized solid in a sealed vial |
| Solubility class | Soluble in water and polar organic solvents | Reconstituted solutions are generally clear |
| Typical storage temperature | -20 degrees Celsius or below, dry | Protect from light; avoid repeated freeze-thaw cycles |
| Common analytical methods | Reversed-phase HPLC-UV, LC-MS | Used for purity estimation and mass confirmation |
| Reported purity range | Area percentage above 95 percent | Reporting practice and acceptance limits differ by laboratory |
Handling guidance for melanotan II follows general practice for small synthetic peptides rather than a product-specific monograph. Lyophilized powder is typically kept at minus twenty degrees Celsius or colder, protected from light and moisture, because warmth and humidity accelerate degradation. Once reconstituted, solutions are usually refrigerated and used within a short window, as hydrolysis and microbial growth both become concerns. Repeated freeze-thaw cycles are generally avoided. These conventions come from laboratory peptide chemistry and not from formal stability studies on this specific compound.
Analytical confirmation of identity relies on mass spectrometry, most often coupled to liquid chromatography. Reversed-phase high-performance liquid chromatography separates the peptide from related impurities and provides a purity estimate based on peak area. Electrospray ionization mass spectrometry then confirms the expected molecular mass, while tandem mass spectrometry can map the fragment sequence. For research-grade material, these two techniques together form the standard minimum. Purity figures reported by vendors are frequently not traceable to an independent laboratory.
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-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.
== Therapeutic potential == Like other opioids, it has potential in pain management; however, by being selective for the delta receptor, multiple undesirable side effects of traditional opioids are not present, such as respiratory depression, sedation, and euphoria. ADL-5859 was also found to be orally active, which makes it easier to administer. Multiple tests have shown its efficacy as an analgesic. It also did not seem to be a convulsant, unlike some other delta agonist opioids.
== Clinical significance == The joint space equals the distance between the involved bones of the joint. A joint space narrowing is a sign of either (or both) osteoarthritis and inflammatory degeneration. The normal joint space is at least 2 mm in the hip (at the superior acetabulum), at least 3 mm in the knee, and 4–5 mm in the shoulder joint. For the temporomandibular joint, a joint space of between 1.5 and 4 mm is regarded as normal. Joint space narrowing is therefore a component of several radiographic classifications of osteoarthritis. In rheumatoid arthritis, the clinical manifestations are primarily synovial inflammation and joint damage. The fibroblast-like synoviocytes, highly specialized mesenchymal cells found in the synovial membrane, have an active and prominent role in the pathogenic processes in the rheumatic joints. Therapies that target these cells are emerging as promising therapeutic tools, raising hope for future applications in rheumatoid arthritis.
== History == The syndrome is named after Edward Treacher Collins (1862–1932), the English surgeon and ophthalmologist who described its essential traits in 1900. In 1949, Adolphe Franceschetti and David Klein described the same condition on their own observations as mandibulofacial dysostosis. The term mandibulofacial dysostosis is used to describe the clinical features.
== Plant interactions == Post-harvest decays are a main source of fruit loss, with the most common source of Citrus fruit decay being infections caused by P. digitatum and P. italicum. Penicillium digitatum is responsible for 90% of citrus fruits lost to infection after harvesting, and is considered the largest cause of post-harvest diseases occurring in California citrus fruits. Its widespread impact derives from the post-harvest disease it causes in citrus fruits known as green rot or mould. As a wound pathogen, the disease cycle begins when P. digitatum conidia germinate with release of water and nutrients from the site of injury on the fruit surface. For example, after infection at 24 °C, rapid growth ensues, with active infection taking place within 48 hours, and initial symptom onset occurring within 3 days. As temperature at time of infection decreases, the delay of initial symptom onset increases. Initial symptoms include a moist depression on the surface, which expands as white mycelium colonizes much of the surface. The centre of the mycelial mass eventually turns olive as conidial production begins. Near the end of the disease cycle, the fruit eventually decreases in size, and develops into an empty, dry shell. This end result is commonly used to distinguish P. digitatum infections from those of P. italicum, which produce a blue-green mould and ultimately render the fruit slimy. Infection with green mould at 25 °C (77 °F) can last 3 to 5 days, with the rate of conidial production per infected fruit being as high as 1–2 billion conidia.
Sources: en.wikipedia.org
Through dietary modification involving the adjustment of menu choices of affected persons from available food sources to optimize vitamin A content. Enriching commonly eaten and affordable foods with vitamin A, a process called fortification. It involves the addition of synthetic vitamin A to staple foods like margarine, bread, flour, cereals, and infant formula during processing. By giving high doses of vitamin A to the targeted deficient population, a method known as supplementation. In regions where deficiency is common, a single large dose is recommended to those at high risk twice a year. Retinol is also used to reduce the risk of complications in measles patients.
== Chemerin-derived peptides == A particular synthetic chemerin-derived peptide, termed C15, was developed at Oxford University. It showed anti-inflammatory activities. Intraperitoneal administration of C15 (0.32 ng/kg) to mice before zymosan challenge conferred significant protection against zymosan-induced peritonitis, suppressing neutrophil (63%) and monocyte (62%) recruitment with a concomitant reduction in proinflammatory mediator expression. C15 was found to promote phagocytosis and efferocytosis in peritoneal macrophages at picomolar concentrations. C15 enhanced macrophage clearance of microbial particles and apoptotic cells by factor of 360% in vitro. Another chemerin-derived peptide, termed C-20, was developed at the Shenzhen Institute of Advanced Technology. Administration C-20 uncovered its high affinity binding to chemerin receptors CMKLR1 and GPR1, mimicking chemerin’s activity but with lower potency. C-20 triggered receptor internalization, promoted chemotaxis, and mildly suppressed hormone production (testosterone and progesterone), suggesting its potential as a tool to study chemerin-related signaling pathways.
Skin conditions resulting from errors in metabolism are caused by enzymatic defects that lead to an accumulation or deficiency of various cellular components, including, but not limited to, amino acids, carbohydrates, and lipids.
Sources: en.wikipedia.org
The dry powder is more stable during transport and storage than a solution. It also allows a known amount of material to be reconstituted at a chosen concentration.
Most certificates state a percentage derived from chromatographic peak area, alongside a mass confirmation. The exact criteria and acceptance thresholds vary between laboratories.
Dry powder is kept frozen or refrigerated and protected from light and moisture. Solutions are handled cold and used promptly to limit degradation.
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.