This is a working overview of MC1R, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-07-16 and is reviewed periodically as new material appears.
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.
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.
Two structural changes distinguish the synthetic peptide from the natural hormone. A norleucine residue replaces methionine at one position, and a D-configured phenylalanine replaces the natural L-form at another. Both substitutions slow enzymatic breakdown, which extends the molecule's persistence relative to the parent hormone. The lactam bridge further constrains the backbone into a stable conformation. These features are standard design strategies in peptide chemistry and are not unique to this compound; they appear across many research peptides built for improved stability.
The compound was developed in the late 1980s and early 1990s by academic researchers investigating melanocortin signaling and pigmentation. Early work explored whether synthetic analogs could reproduce effects of the natural hormone under controlled conditions. The molecule never advanced through the full regulatory pathway required for approval as a medicine. From the mid-2000s onward it appeared in unregulated consumer markets, often distributed through informal channels. That gap between research origins and commercial availability shapes how the compound is discussed today.
Melanotan-2 is a synthetic peptide designed as an analog of alpha-melanocyte-stimulating hormone, a signaling molecule produced in the pituitary and skin. Its structure is a linear chain of seven amino acids that folds into a ring through an internal lactam bridge joining two side chains. The compound is sometimes written as MT-II or MEL-2 in informal and commercial contexts. It belongs to the melanocortin peptide family, a group of short signaling molecules that share a conserved core sequence recognized by melanocortin receptors.
| 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.
Independent verification is central to quality control because the compound is not produced under pharmaceutical manufacturing standards. Third-party laboratories can measure purity, identity, residual solvents, and microbial contamination, though the scope of testing varies between services. Reported analyses of vendor samples have shown batch-to-batch variation in peptide content and the presence of truncated or oxidized species. How much of this variation reflects synthesis conditions versus storage and shipping is not well characterized. No harmonized reference standard exists for the material as sold.
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.
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.
n orientation One of two possible orientations by which a linear DNA fragment can be inserted into a vector, specifically the one in which the gene maps of both fragment and vector have the same orientation. Contrast u orientation.
Antineoplastic agents – Substances that inhibit or prevent the proliferation of neoplasms. Antisickling agents – Agents used to prevent or reverse the pathological events leading to sickling of erythrocytes in sickle cell conditions. Nucleic acid synthesis inhibitors – Compounds that inhibit cell production of DNA or RNA. Enzyme inhibitors – Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction. Cytochrome P-450 CYP2D6 inhibitors – Agents that inhibit one of the most important enzymes involved in the metabolism of xenobiotics in the body, CYP2D6, a member of the cytochrome P450 mixed oxidase system.
=== Hypercycle with translation === A hypercycle with translation consists of polynucleotides Ii (with concentration xi) and polypeptides Ei (with concentration yi). It is assumed that the kinetics of nucleotide synthesis follows a Michaelis–Menten-type reaction scheme in which the concentration of complexes cannot be neglected. During replication, molecules form complexes IiEi-1 (occurring with concentration zi). Thus, the total concentration of molecules (xi0 and yi0) will be the sum of free molecules and molecules involved in a complex:
== Background == The development of eugenics in the United States during the late nineteenth and early twentieth centuries created a foundation for policies targeting marginalized populations for sterilization. Eugenic ideology promoted the belief that sterilization would prevent "undesirable" children from being born. Undesirable traits correlated with reproductive fitness which included race and ethnicity. In the late nineteenth and early twentieth century, the immigration rates in the United States spiked along with the reproduction rates in immigrant families. This provoked a deeper fear from eugenicists that native born Americans and Americans with strong reproductive fitness would be outnumbered by immigrants who possess a low reproductive fitness. This fear became ingrained into many Americans across the nation and became fuel for the sterilization of Latinas movements in the twentieth century. Latina women were particularly vulnerable to eugenic sterilization policies due to racialized beliefs that cast them as inferior and unfit to reproduce. In California, eugenics programs were tied to broader efforts to reduce immigration from Mexico. Mexican American women were stereotyped as excessively fertile, unfit parents, criminally inclined, and intellectually inferior. Figures in support of Eugenics advocated for and promoted these beliefs to the public. Charles M. Goethe played a key role in popularizing eugenic ideas in California, and he founded the Eugenics Society of Northern California.
Sources: en.wikipedia.org
That started probably [in February], as we geared up to conclude our phase I trial and release data. Although the NRC is capped at $10 million, which is certainly not sufficient to carry out phase II and phase III trials, the NRC has, through the bureaucracy, elevated us back up to the strategic innovation fund. That occurred about three weeks ago. We're now working with the strategic innovation fund." He later said that no reply had been received from the government. In a meeting with the federal COVID-19 vaccine task force and Sorenson, task force members expressed concerns that "Providence might not be able to scale up production fast enough".
The Oxford team analysed the chemical properties of the cephalosporin ring system, opening the door to the production of semisynthetic cephalosporins created through replacing side chains, as had been done with penicillin to create semisynthetic penicillins. "Everybody I have questioned who was involved in the development of cephalosporin C," science writer David Wilson reported, "when asked if one man was responsible for keeping the project going, replied: 'Florey'." Controversy over British firms having to pay royalties to American ones for the use of the deep submergence techniques developed in the United States to produce penicillin when penicillin was seen as a British innovation led to the establishment of the National Research Development Corporation (NRDC) in June 1948. The Oxford team patented their work on cephalosporins and assigned the patents to the NRDC. By 1978, the annual world sales of cephalosporins were worth over £600,000 (equivalent to £3,279,000 in 2025) and the NRDC was reaping £100,000 (equivalent to £546,000 in 2025) a year in royalties. Florey received a 0.5 per cent share in the last two years of his life.
=== Actinium-226 === Actinium-226 is an isotope of actinium with a half-life of 29.37 hours. It mainly (83%) undergoes beta decay, sometimes (17%) undergo electron capture, and rarely (0.006%) undergo alpha decay. There are researches on 226Ac to use it in SPECT.
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 seven-amino-acid peptide modeled on alpha-melanocyte-stimulating hormone. It carries two non-natural substitutions and a cyclic bridge that increase its stability relative to the natural hormone. It circulates as a research chemical and is not an approved medicine.