melanotan-2 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 2026-06-14 and is reviewed periodically as new material appears.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
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controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports.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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Alpha-MSH analogue with a lactam ring |
| Molecular formula | C50H69N15O9 | Commonly cited value for the neutral peptide |
| Molecular weight | 1024.18 g/mol | Calculated for the free molecule |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water, DMSO and ethanol | Dissolution in pure water is often slow |
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.
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.
Routine characterisation relies on reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, using a C18 column and a water-acetonitrile gradient containing trifluoroacetic acid. Electrospray ionisation mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidised by-products that co-elute poorly. Sequence and stereochemistry require additional work, such as peptide mapping or amino acid analysis, because a chromatographic purity figure alone does not distinguish a diastereomer from the target peptide. Independent testing of research-grade material frequently shows measured content below the stated label, so a certificate of analysis is best read together with the method that produced it.
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.
For Canadian domestic consumption of non-CRFPCP pork, ractopamine hydrochloride is permitted to be sold over the counter with applications in meal or pellet feed for finishing barrows and gilts (up to 10 mg/kg for last six weeks), confined finishing cattle (up to 30 mg/kg for last 42 days), and finishing heavy turkeys (up to 9 mg/kg for 14 days). The withdrawal period was set to 0 days.
=== 14 May === Russian missiles struck Ternopil Oblast, causing damage to civilian property. The Russian military claimed to have launched strikes on deployment points of Ukrainian forces and arms depots in the oblast as well as in Petropavlivka in Dnipropetrovsk Oblast. The Governor of Russia's Bryansk Oblast said a Ukrainian drone attack damaged a food processing facility in Starodub. The Russian Ministry of Defence confirmed the death of Colonels Vyacheslav Makarov and Yevgeny Brovko of the 4th Motorized Rifle Brigade during fighting in Bakhmut. The Russian military said it had repelled Ukrainian attacks in the north and south of Bakhmut while Yevgeny Prigozhin, head of the Wagner Group said his forces had advanced up to 130 metres (430 ft) over the past 24 hours. He also claimed control over 28 multi-story buildings in western districts of Bakhmut and estimated Ukrainian forces were still holding 20 buildings and a total area of 1.69 square km (0.65 square miles). Meanwhile, the Ukrainian Defence Ministry said its forces captured more than ten enemy positions in the north and south of Bakhmut and cleared a large area of forest near Ivanivske. The Washington Post, citing leaked documents from the Pentagon, reported that Prigozhin secretly contacted Ukrainian intelligence in January 2023 to reveal Russian military positions in exchange for a Ukrainian withdrawal from Bakhmut, which was refused, and advised them to advance towards Crimea while informing them of shortages in Russian ammunition.
== Awards and honors == 2014 – Silver Medal for "erma-Promp: Socks for xerosis treatment in diabetic feet, 42nd International Exhibition of Inventions of Geneva 2018 – Leader of Innovation prize, 11th International Invention and Innovation Show INTARG 2019 – Leadership Award (Grand Officer), British High Commission 2019 – Outstanding Professional Women Award, Federation of Business and Professional Women of Thailand 2021 – Gold Medal for "Sericin and chitosan cream for preventing and limiting the progressive of pressure sore", International Invention & Trade Expo 2024 – National Outstanding Researcher Award, NRCT
== Disorders == Bradykinin is also thought to be the cause of the dry cough in some patients on widely prescribed angiotensin-converting enzyme (ACE) inhibitor drugs. It is thought that bradykinin is converted to inactive metabolites by ACE, therefore inhibition of this enzyme leads to increased levels of bradykinin; increased bradykinin sensitizes somatosensory fibers and thus causes hyperalgesia. Bradykinin may mediate this via pro-inflammatory peptides (e.g. substance P, neuropeptide Y) and a local release of histamine. In severe cases, the elevation of bradykinin may result in angioedema, a medical emergency. People of African descent have up to five times increased risk of ACE inhibitor induced angioedema due to hereditary predisposing risk factors such as hereditary angioedema. This refractory cough is a common cause for stopping ACE inhibitor therapy. Overactivation of bradykinin is thought to play a role in a rare disease called hereditary angioedema. Low levels of bradykinin in the body correlate with obesity in adolescents; it has been proposed that bradykinin can be used as a biomarker for metabolic syndrome. Bradykinins have been implicated in a number of cancer progression processes. Increased levels of bradykinins resulting from ACE inhibitor use have been associated with increased lung cancer risks. Bradykinins have been implicated in cell proliferation and migration in gastric cancers, and bradykinin antagonists have been investigated as anti-cancer agents.
Sources: en.wikipedia.org
== Synthesis == PEEK polymers are obtained by step-growth polymerization by the dialkylation of bisphenolate salts. Typical is the reaction of 4,4'-difluorobenzophenone with the disodium salt of hydroquinone, which is generated in situ by deprotonation with sodium carbonate. The reaction is conducted around 300 °C in polar aprotic solvents - such as diphenyl sulfone.
== Regulation == The regulation of the glyoxylate cycle involves carbon source availability, as it controls the transcriptional levels of key enzymes. Carbon catabolite repression is the main process that occurs in bacteria and fungi that regulates the transcriptional levels of the glyoxylate cycle, ensuring that the cycle is activated when glucose is not available. For instance, in Escherichia coli, the regulation of the isocitrate branch point takes place by regulating the transcription level of IclR and FadR, and through AceK, which is a bifunctional enzyme that acts as both a dehydrogenase kinase and a phosphatase. AceK is responsible for the regulation of isocitrate dehydrogenase and its switching roles in the citric acid cycle as well as the glyoxylate cycle. It determines whether the carbon atoms will be used in the glyoxylate cycle or the citric acid cycle. The phosphorylation, catalyzed by the AceK kinase function, of isocitrate dehydrogenase decreases its activity, and this phosphorylation can be reversed. In plants, the regulation of the glyoxylate cycle is achieved by regulating transcriptional levels during the seed germination process and through the mobilization of stored lipids . In bacteria, such as Mycobacterium tuberculosis, the glyoxylate cycle is up regulated especially when glucose is scarce and is needed during host infection. This regulation contributes to the growth and virulence of the pathogenic infection. Overall, these regulations allow for the conservation of carbon and activate the biosynthesis of key metabolites when carbon source is limited.
== Animal studies == Because of its significant role in the transportation of organic anion molecules and recent association with multiple illnesses including Alzheimer's disease (AD), the ABCC1 protein has become a potential drug target. In ABBC1 knockout mice, β-amyloid clearance is much lower than in wild-type mice that expressed the gene. Furthermore, in mouse models of AD, treatment with thiethylperazine, a drug that activates ABBC1, increases β-amyloid clearance and decreases in the amount of β-amyloid found in the brains. St. John's wort, a substance containing the chemical hyperforin, has also been shown to have a positive effect on activity levels of ABCC1. In a study of the effects of St. John's wort on APP-tg mice, an extract of St. John's wort that contained decreased levels of hyperforin increased the activity of ABCC1 by 70 percent and led to decreased amounts of β-amyloid in the brain and increased cognitive function in the mice.
The enzyme most responsible for estradiol 4-hydroxylation is CYP1B1. In humans, CYP1B1 mRNA and protein exhibit constitutive expression in the lung and kidney, as well as estrogen-regulated tissues such as breast, ovary and uterus. Whereas 4-hydroxylation constitutes the minor pathway in the liver, the greater proportion of CYP1B1 expression in extrahepatic tissues shifts the balance in favor of 4-OH-E2 formation. 4-OH-E2 is thought to be the most carcinogenic of all the estradiol metabolites, especially considering that CYP1B1 exhibits overexpression in breast cancer tumors. 4-OH-E2, like 2-OH-E2, can be physiologically active as well as tumorigenic. 4-OH-E2 is capable of binding ER with a reduced dissociation rate and prolonged activation, thereby inducing cellular growth and proliferation, adenohypophyseal hormone secretion, and prostaglandin production. Das et al. implicated 4-OH-E2 in the induction of estrogen-responsive genes, a response that exhibited partial or no abrogation by coadministration with an antiestrogen, providing evidence for the ability of 4-OH-E2 to carry out genetic upregulation via a pathway independent of ER signalling. Effects independent of ER binding include breakage of single-stranded DNA, especially when interacting synergistically with nitric oxide in human breast cancer cells and the production of quinones and free radicals. CYP1B1 can be induced by E2. ERα, after binding to estradiol, interacts with the CYP1B1 ERE to stimulate CYP1B1 expression.
==== Endothelial keratoplasty ==== Endothelial keratoplasty replaces the patient's endothelium with a transplanted disc of posterior stroma/Descemets/endothelium (DSEK) or Descemets/endothelium (DMEK). This relatively new procedure has revolutionized treatment of disorders of the innermost layer of the cornea (endothelium). Unlike a full-thickness corneal transplant, the surgery can be performed with one or no sutures. Patients may recover functional vision in days to weeks, as opposed to up to a year with full thickness transplants. However, an Australian study has shown that despite its benefits, the loss of endothelial cells that maintain transparency is much higher in DSEK compared to a full-thickness corneal transplant. The reason may be greater tissue manipulation during surgery, the study concluded. During surgery the patient's corneal endothelium is removed and replaced with donor tissue. With DSEK, the donor includes a thin layer of stroma, as well as endothelium, and is commonly 100–150 μm thick. With DMEK, only the endothelium is transplanted. In the immediate postoperative period the donor tissue is held in position with an air bubble placed inside the eye (the anterior chamber). The tissue self-adheres in a short period and the air is adsorbed into the surrounding tissues. Complications include displacement of the donor tissue requiring repositioning ("refloating"). This is more common with DMEK than DSEK. Folds in the donor tissue may reduce the quality of vision, requiring repair. Rejection of the donor tissue may require repeating the procedure.
Sources: en.wikipedia.org
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.
No national medicines agency has approved melanotan-2 for clinical use. Afamelanotide, a related but distinct peptide, holds a marketing authorisation in the European Union for a rare photosensitivity disorder. Melanotan-2 itself is handled as a laboratory chemical.
Its broad activity across melanocortin receptors makes it a tool for probing pigmentation, appetite and vascular signalling. Early trials recorded skin darkening and other effects that were not the original focus of the work. Those observations generated hypotheses that later studies have examined.
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.