Melanotan II raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2025-10-18 and is reviewed periodically as new material appears.
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
Melanotan II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Cyclic heptapeptide, C-terminally amidated |
| Approximate molecular mass | 1024 Da | Monoisotopic mass of the free peptide |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility class | Soluble in water and polar solvents | Also dissolves in neutral aqueous buffer |
| Common synonyms | Melanotan II, MT-II, MT-2 | Described as a melanocortin agonist in early literature |
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.
Melanotan II is a synthetic cyclic heptapeptide that acts as an agonist at melanocortin receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide involved in pigment production. The analogue carries a lactam bridge that constrains the ring and slows enzymatic breakdown relative to the native hormone. In research literature it appears under several abbreviations, and naming conventions are not fully standardized. Published descriptions usually place it within the broader melanocortin agonist family.
Because the substance circulates mainly through informal markets, verification is a recurring theme in technical discussion. Independent analyses have found that labeled content and actual content can diverge, and that purity varies between samples. Analytical laboratories use reversed-phase chromatography to separate components and mass spectrometry to confirm identity. Isotope-labeled internal standards improve quantification in complex matrices. Such methods describe what a sample contains but say nothing about its sterility, lawful status, or suitability for any use. Open questions remain about how consistently testing is applied across the supply chain.
Regulatory treatment of this peptide varies by country. It holds no marketing authorization as a medicine in the United States, the European Union, or most other jurisdictions. Some countries classify products containing it as prescription-only or unlicensed medicines, which restricts lawful supply. Authorities have issued public notices warning that unregulated products may contain undeclared or incorrect ingredients. The molecule also appears on prohibited lists for competitive sport. These measures address supply oversight rather than any approved therapeutic role.
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.
Regulatory treatment varies by jurisdiction and has changed over time. In several countries the peptide is handled as an unapproved prescription medicine, and import or sale for human use is restricted, while elsewhere it falls under poisons or controlled-substance schedules. Enforcement activity against online vendors has been reported in Australia, New Zealand, the United Kingdom and the United States. Scholarly writing discusses melanotan-2 chiefly as an experimental tool and as a case study in unregulated peptide supply, and its precise legal position in any given country should be checked against current national schedules.
Lyophilised melanotan-2 is comparatively robust when kept dry, cold and dark, and a desiccated powder stored at minus twenty degrees Celsius or below is generally expected to retain its chemical integrity for extended periods. In solution the peptide is far less stable, with degradation proceeding through oxidation of tryptophan and histidine residues, hydrolysis adjacent to the lactam bridge, and aggregation at higher concentrations. Repeated freeze-thaw cycling accelerates loss of the parent peak. Working aliquots are therefore prepared once, held cold, and used without letting the stock return to ambient temperature.
Quality assessment of research-grade peptide rests mainly on reversed-phase high-performance liquid chromatography for purity and on mass spectrometry for identity confirmation. A single main peak above a stated threshold, commonly ninety-eight percent by peak area, is the usual release criterion applied by suppliers. Independent analyses commissioned by laboratories and consumer organisations have repeatedly reported discrepancies between label claims and measured content, including truncated sequences, residual trifluoroacetate, and lower-than-declared peptide mass. Those findings do not establish that every supplier is unreliable, but they indicate that purity figures printed on a vial are claims requiring verification rather than settled facts.
Disposal of plutonium waste from nuclear power plants and dismantled nuclear weapons built during the Cold War is a nuclear-proliferation and environmental concern. Other sources of plutonium in the environment are fallout from many above-ground nuclear tests, which are now banned.
[W]e find that the European Communities did not actually proceed to an assessment, within the meaning of Articles 5.1 and 5.2, of the risks arising from the failure of observance of good veterinary practice combined with problems of control of the use of hormones for growth promotion purposes. The absence of such risk assessment, when considered in conjunction with the conclusion actually reached by most, if not all, of the scientific studies relating to the other aspects of risk noted earlier, leads us to the conclusion that no risk assessment that reasonably supports or warrants the import prohibition embodied in the EC Directives was furnished to the Panel. We affirm, therefore, the ultimate conclusions of the Panel that the EC import prohibition is not based on a risk assessment within the meaning of Articles 5.1 and 5.2 of the SPS Agreement and is, therefore, inconsistent with the requirements of Article 5.1.
After finding out that Apoth was using children to disseminate a technological drug called Overclock, Mister Sinister modified Overclock to allow Psylocke to interact with Apoth in a cyberspace, killing Apoth, whose remains she delivered to Mister Sinister in exchange for his assistance in keeping this extrajudicial mission a secret from the Krakoan Quiet Council. Following the Apoth incident, Psylocke was assigned to monitor Mister Sinister's new team of Hellions, composed of mutants considered too violent or troubled to assimilate into Krakoan society. The character was later featured as a team member in the Marauders (vol. 2) as the team was refocused on their mission of mutant rescue. Following the fall of Krakoa, Kwannon headlined Psylocke (vol. 2), written by Alyssa Wong with art by Vincenzo Carratù, spun out of the events of Jed MacKay and Ryan Stegman's X-Men (vol. 7) where Kwannon was a team member.
=== Contaminant removal === Graphene oxide is non-toxic and biodegradable. Its surface is covered with epoxy, hydroxyl, and carboxyl groups that interact with cations and anions. It is soluble in water and forms stable colloid suspensions in other liquids because it is amphiphilic (able to mix with water or oil). Dispersed in liquids it shows excellent sorption capacities. It can remove copper, cobalt, cadmium, arsenate, and organic solvents.
=== Yield Stress Measurement in Hydrogels === The yield stress of a hydrogel can be measured using the collapse test, a method commonly applied to materials suitable for 3D printing. In this test, a filament of hydrogel is printed on top of a series of plastic blocks with progressively increasing gaps between them. A side-view image of the filament is then taken, showing the angle the hydrogel filament forms with the vertical axis. This collapse angle provides a measurable indicator of the material's yield stress. Ribeiro et al. (2017) established a set of equations to relate the collapse angle to the hydrogel's yield stress, providing a quantitative framework for assessing bioink shape fidelity in 3D bioprinting. These equations were later generalised in 2024 to account for non-symmetrical geometries and large deformations in hydrogels tested under similar collapse conditions.
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== Uses == The plant is grown in the Taklamakan Desert, and is traditionally used for medicines and foods in China. The main sources of the Chinese herbal medicine cistanche (Chinese: 肉苁蓉, pinyin ròucōngróng) are Cistanche salsa and Cistanche deserticola, although it may also be obtained from C. tubulosa. The drug, known in Chinese as suosuo dayun, is collected in spring before sprouting, by slicing the stems of the plant.
== Discovery of PTD-DBM == Professor Kang-Yell Choi and his research team at Yonsei University in South Korea discovered a protein responsible for hair loss in the condition known as androgenetic alopecia. The responsible protein is called CXXC-type zinc finger protein 5 (CXXC5), which acts as a negative regulator for the Wnt/β-catenin pathway, involved in hair regeneration and wound healing. CXXC5 negatively regulates hair growth, and the researchers developed a new substance that promotes hair regeneration by controlling the function of CXXC5. When CXXC5 binds with the Dvl protein, which functions at the upstream of Wnt/β-catenin pathway, it suppresses hair regrowth and hair follicle neogenesis. The observation of CXXC5 overexpression in the bald scalp by Professor Choi’s team led to the development of PTD-DBM, which interferes with the CXXC5-Dvl protein-protein interaction (PPI). By topical application, PTD-DBM enhances hair regrowth as well as neogenesis. The hair growth promoting effect of PTD-DBM is further enhanced when used in combination with a Wnt/β-catenin signaling activator such as VPA, which is generally used as a drug for bipolar disorder and activates the Wnt/β-catenin pathway by inhibition of GSK3β. Currently, topical application of PTD-DBM or its combination with VPA has been used for treatment of hair loss.
hemizygous In a diploid organism, having just one allele at a given genetic locus (where there would ordinarily be two). Hemizygosity may be observed when only one copy of a chromosome is present in a normally diploid cell or organism, or when a segment of a chromosome containing one copy of an allele is deleted, or when a gene is located on a sex chromosome in the heterogametic sex (in which the sex chromosomes do not exist in matching pairs); for example, in human males with normal chromosomes, almost all X-linked genes are said to be hemizygous because there is only one X chromosome and few of the same genes exist on the Y chromosome.
=== Transportation and detoxification === This could happen in two different ways: ammonia itself might simply diffuse (as NH3) or be transported (as NH4+) across the cell membranes in and out of the extracellular space, or a shuttle system involving carrier molecules (amino acids) might be employed. Certainly, ammonia can diffuse across lipid membranes, and it has been shown that ammonia can be transported by K+/Cl− co-transporters.
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== Therapeutic potential == In a test of pharmacologic asprosin depletion in animals, preliminary results raised the possibility of its use, therapeutically, in treating type 2 diabetes and obesity. For instance, Chopra and coworkers observed that when monoclonal antibodies targeting asprosin were injected into diabetic mice, blood glucose and insulin levels improved.
assistance to Mexican security forces has conflicted with the Leahy Law, which prohibits aid to units implicated in human rights abuses, pointing to cases where trained units were later accused of violations.
== Therapeutic use and drug development == Opinions regarding the use of ANP for the treatment of acute heart failure and kidney disease are varied. While this molecule has been shown to successfully restore some hemodynamic parameters following heart failure, and yield clinical improvement for kidney injury, whether it ultimately reduces mortality and its long-term effects are unknown. Therefore, more studies need to be conducted to better understand the therapeutic effects of ANP. Newly synthesized homologues of ANP molecule are being assessed for the treatment of acute heart failure. Preliminary research on one of such molecules, ularitide, has shown that this drug is safe, well tolerated, and effective in the treatment of acute heart failure.
== Overdose == An overdose of pregabalin usually consists of severe drowsiness, severe ataxia, blurred vision, slurred speech, uncontrollable jerking motions (myoclonus), and anxiety. In one case study, macular detachment was reported with overdose Despite these symptoms an overdose is not usually fatal unless mixed with another CNS depressant. Several people with kidney failure developed myoclonus while receiving pregabalin, apparently as a result of the gradual accumulation of the drug. Acute overdosage may be manifested by drowsiness, tachycardia, and hypertonia. Plasma, serum, or blood concentrations of pregabalin may be measured to monitor therapy or to confirm a diagnosis of poisoning in hospitalized people.
== Research == Vedolizumab eventually completed a number of phase III clinical trials for Crohn's Disease and Ulcerative Colitis (GEMINI I, GEMINI II, and GEMINI III) that demonstrate that vedolizumab is an effective and well tolerated drug. The results of the GEMINI 1 and GEMINI 2 randomized, placebo controlled multicenter trials of induction and maintenance therapy in Crohn's disease and ulcerative colitis have been published. An additional clinical trial, GEMINI LTS (Long-term Safety), was completed in October 2017.
Sources: en.wikipedia.org
No. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.
Afamelanotide is the linear analogue [Nle4-D-Phe7]-alpha-MSH, sometimes called melanotan I, while melanotan II is cyclic and carries three further substitutions. The two are distinct molecules and are not interchangeable in analytical testing.
Binding to the four melanocortin receptor subtypes is well documented in vitro. The relative contribution of each subtype to whole-body effects in humans is far less certain.
The lyophilized powder is generally held at minus twenty degrees Celsius or below, away from light and moisture. Reconstituted solutions are typically refrigerated and used quickly. These practices derive from general peptide handling rather than a formal stability study.