Everything below concerns melanocortin receptor. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-04-26. Numbers and descriptions here follow the published literature rather than marketing material.
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
No regulatory authority has approved melanotan-2 for human use, and several countries classify it as a prescription-only or controlled substance, which restricts lawful supply. Material sold online is generally labelled as a research chemical and is not required to meet pharmaceutical standards of identity or purity. Published human data consist mainly of small uncontrolled studies, case reports and adverse-event notifications, so the evidence base is descriptive rather than confirmatory. Whether repeated melanocyte stimulation alters long-term naevus behaviour remains an open question that no completed trial has resolved.
Lyophilised melanotan-2 is supplied as a solid, which is more stable than a solution. The material is hygroscopic, so weighing is done quickly, in low humidity, with the container kept sealed. Reconstitution usually uses water for injection or bacteriostatic water, added down the wall of the vial to limit foaming. A reconstituted solution is held at 2 to 8 °C and kept away from light. Repeated freezing and thawing of the same vial is avoided because ice crystal formation and concentration effects degrade the peptide.
Reversed-phase high-performance liquid chromatography is the routine method for purity assessment. Peptides absorb near 214 nm because of the peptide bond, and a gradient of acetonitrile in water separates the intact peptide from deletion sequences, oxidised products, and earlier-eluting fragments at neutral pH. Electrospray ionisation mass spectrometry provides an orthogonal check: the measured mass must agree with the theoretical value. Amino acid analysis and peptide mapping confirm structure but are used less often. Reference standards remain scarce because the peptide is not described in any pharmacopoeia.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms add to total mass |
| Molecular mass | About 1024 daltons | Calculated for the free base |
| Structural class | Cyclic heptapeptide | Contains D-phenylalanine and norleucine |
| Parent hormone | Alpha-melanocyte-stimulating hormone | Endogenous tridecapeptide of 13 residues |
| Receptor profile | Non-selective melanocortin agonist | Interacts with MC1R, MC3R, MC4R and MC5R |
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.
Melanotan-2 has not received marketing authorisation from major regulatory agencies for any therapeutic indication. Several jurisdictions classify it as a prescription-only medicine or a controlled substance when supplied for human use. Because approved products do not exist, material sold online usually sits outside pharmaceutical supply chains and formal quality oversight. Regulators have issued public notices describing the compound as unapproved. Enforcement varies, and the legal position differs between countries, which complicates any single general statement about its status.
Scientific discussion of Melanotan-2 spans pharmacology, dermatology, and public-health literature. Laboratory studies examine its receptor binding and cellular effects, while clinical reports describe outcomes observed after unregulated use. These two bodies of work differ in rigour and intent. Peer-reviewed trials of the compound as a medicine are limited, so much of the available information comes from case reports and surveillance data. Authors frequently note the gap between experimental findings and real-world use.
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.
Receptor-binding studies classify melanotan II as a non-selective melanocortin agonist. It interacts with MC1R, MC3R, MC4R and MC5R, with reported affinities in the low nanomolar range and no strong subtype preference. Activation of MC1R on dermal melanocytes shifts pigment synthesis toward eumelanin, the dark polymer deposited in melanosomes and transferred to keratinocytes. Because the same peptide engages MC4R in the hypothalamus, it also appears in animal work on food intake and erectile response, which is why it is discussed in both pigment and metabolic research. Which receptor populations dominate after systemic exposure in humans is not fully established.
=== Mucosal surface delivery === Alternatives included aerosol instillation of naked DNA on mucosal surfaces, such as the nasal and lung mucosa, and topical administration of pDNA to the eye and vaginal mucosa. Mucosal surface delivery has also been achieved using cationic liposome-DNA preparations, biodegradable microspheres, attenuated Salmonalla, Shigella or Listeria vectors for oral administration to the intestinal mucosa and recombinant adenovirus vectors.
Most research suggests that the positive effects of most of the bulking agents seem to reduce after 6 to 12 months. Endoanal ultrasound has sometimes been used to assess the presence of the material at follow up. At 6 months the material has been reported as missing or migrated in 18.4% of cases, at 3 years or more in 20.2% of cases. NASHA Dx and ALTA injection may have longer lasting effects, with most patients still having improvement after 3 years.
== Metabolism == As an essential amino acid, phenylalanine is not synthesized by animals, which must obtain it from dietary sources such as meat, dairy, eggs, and legumes. Bacteria, archaea, fungi, algae, some protozoans and plants biosynthesize phenylalanine via the shikimate pathway. While animals cannot synthesize phenylalanine, they can break it down. Through an irreversible reaction, the liver enzyme phenylalanine hydroxylase (PAH) converts phenylalanine into tyrosine. L-Phenylalanine is biologically converted into L-tyrosine, another one of the DNA-encoded amino acids. L-tyrosine in turn is converted into L-DOPA, which is further converted into dopamine, norepinephrine (noradrenaline), and epinephrine (adrenaline). The latter three are known as the catecholamines. Phenylalanine uses the same active transport channel as tryptophan to cross the blood–brain barrier. In excessive quantities, supplementation can interfere with the production of serotonin and other aromatic amino acids as well as nitric oxide due to the overuse (eventually, limited availability) of the associated cofactors, iron or tetrahydrobiopterin. The corresponding enzymes for those compounds are the aromatic amino acid hydroxylase family and nitric oxide synthase.
Sources: en.wikipedia.org
Soap solutions, cosmetics, and toothpaste Food such as butter, cheese, jam, mayonnaise, soup, and yogurt Natural substances such as gums, protein solutions, and extracts Biological fluids such as blood, saliva, semen, mucus, and synovial fluid agricultural waste, magma, and lava, Slurries such as cement slurry and paper pulp,
In a famous game in 2004, with 35 seconds remaining and the scores deadlocked at 131 points apiece, Essendon legend James Hird swooped on a loose ball in the right forward pocket and snapped a match-winning goal with his 15th possession for the quarter, famously hugging an Essendon supporter in the crowd in a moment of jubilation after being fined $20,000 earlier in the week for criticising umpire Scott McLaren. Full-forward Matthew Lloyd also kicked eight goals during the game to net three Brownlow votes. Despite Hird's incredible individual effort, and to the consternation of fans and the audience of the 2004 Brownlow medal count, he did not receive any Brownlow Medal votes from the umpires for his 34 disposals and clutch goals, which some have speculated was in retribution for his tirade against umpire McLaren.
=== T cells === Some T cells (e.g. regulatory T cells) release TGF-β1 to inhibit the actions of other T cells. Specifically, TGF-β1 prevents the interleukin(IL)-1- & interleukin-2-dependent proliferation in activated T cells, as well as the activation of quiescent helper T cells and cytotoxic T cells. Similarly, TGF-β1 can inhibit the secretion and activity of many other cytokines including interferon-γ, tumor necrosis factor-alpha (TNF-α), and various interleukins. It can also decrease the expression levels of cytokine receptors, such as the IL-2 receptor to down-regulate the activity of immune cells. However, TGF-β1 can also increase the expression of certain cytokines in T cells and promote their proliferation, particularly if the cells are immature.
Sources: en.wikipedia.org
[A]n overwhelming preponderance of power [...] will remain wholly unattainable unless the Allies win the present war and the United States assumes responsibilities commensurate with its power—in the war, in the peace after the war and in the maintenance and improvement of the new order after the peace. The necessary preponderance of power is unlikely to emerge from any international combination other than a permanent alliance of the United States, the British Commonwealth of Nations, and the French Republic, with the addition of such Latin American states and such European democracies as may care to join. Such a coalition, if stable and permanent, could put an end to the world balance of power and oblige outside powers to abandon the game of power politics. No other coalition presently in prospect would seem to offer any comparable hope. In 1941, Alfred Vagts wrote an article, titled "The United States and the Balance of Power," in which he recalled the words of Thomas Jefferson:
=== Off-label drugs === α2-Adrenergic receptor agonists (e.g., clonidine, guanfacine) Anticonvulsants/mood stabilizers (e.g., valproic acid, lamotrigine) Antipsychotics (non-licensed) (e.g., haloperidol, olanzapine) Cannabinoids (e.g., cannabis, dronabinol, nabilone) Dietary supplements (e.g., N-acetylcysteine, omega-3 fatty acids, sulforaphane) Entactogens (serotonin releasing agents) (e.g., MDMA) Melatonin receptor agonists (e.g., melatonin) NMDA receptor antagonists (e.g., memantine, amantadine) Norepinephrine reuptake inhibitors (NRIs) (e.g., atomoxetine) Opioid receptor antagonists (e.g., naltrexone) Other antidepressants (e.g., mirtazapine) Oxytocin receptor agonists (e.g., oxytocin) Probiotics and prebiotics Psychostimulants (norepinephrine–dopamine releasing agents and/or reuptake inhibitors) (e.g., amphetamine, methylphenidate) Selective serotonin reuptake inhibitors (SSRIs) (e.g., fluoxetine, fluvoxamine, sertraline, citalopram) Serotonergic psychedelics (e.g., psilocybin, lysergic acid diethylamide (LSD)) Serotonin–norepinephrine reuptake inhibitors (SNRIs) (e.g., milnacipran) Serotonin releasing agents (e.g., fenfluramine—withdrawn and no longer recommended) Serotonin 5-HT1A receptor agonists (e.g., buspirone) Tricyclic antidepressants (TCAs) (e.g., clomipramine)
A number of studies measuring anabolic steroid use in high school athletes found that out of all 12th grade students, 6.6 percent of them had used anabolic steroids at some point in their high school careers or were approached and counseled to use them. Of those students who acknowledged doping with anabolic–androgenic steroids, well over half participated in school-sponsored athletics, including football, wrestling, track and field, and baseball. A second study showed 6.3 percent of high school student Football players admitted to current or former AAS use. At the collegiate level, surveys show that AAS use among athletes range from 5 percent to 20 percent and continues to rise. The study found that skin changes were an early marker of steroid use in young athletes, and underscored the important role that dermatologists could play in the early detection and intervention in these athletes.
Sources: en.wikipedia.org
No regulatory agency has authorised melanotan-2 as a medicine for any indication. It circulates mainly as a research chemical or through unregulated channels. As a result, identity, purity and content are not independently guaranteed.
Melanotan-1, also called afamelanotide, is a linear analogue with greater selectivity for MC1R and has received approval in some jurisdictions for a specific photosensitivity disorder. Melanotan-2 is cyclic, less selective, and reaches central receptors more readily. The two are often confused in online discussion despite different pharmacology and regulatory status.
Alpha-MSH is an endogenous tridecapeptide derived from pro-opiomelanocortin. Melanotan-2 reproduces its core receptor-binding sequence inside a shortened, stabilised ring. The result is a molecule with a longer effective half-life and higher potency than the parent hormone.
Low temperature slows hydrolysis and oxidation, the two main routes by which the peptide backbone and side chains are modified. A lyophilised powder stored at −20 °C is more stable than one kept at room temperature, and once the material is dissolved the degradation rate rises, making refrigeration more important.