Everything below concerns eumelanin. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-06-27. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Melanotan-2 is a synthetic cyclic heptapeptide designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous tridecapeptide that regulates pigment production. Two modifications distinguish it from the natural hormone: norleucine replaces methionine at the N-terminus, which limits oxidation, and a D-phenylalanine substitution raises receptor affinity. The ring is closed through an aspartate-lysine lactam bridge, giving the molecule a constrained conformation. The free base has a molecular mass near 1024 daltons, and commercial material is usually supplied as an acetate salt. It appears in the literature as a research peptide rather than an approved therapeutic agent.
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.
Solid peptide kept dry at minus twenty degrees Celsius, shielded from light and moisture, is generally considered stable for extended periods. Solutions are divided into single-use aliquots and held at minus twenty or minus eighty degrees Celsius, because repeated freeze-thaw cycles promote aggregation and loss of material to container surfaces. Hydrolysis of the backbone and oxidation of tryptophan are the principal degradation routes in aqueous solution, and both accelerate at ambient temperature. Hygroscopic uptake after a vial is opened can also shift the actual mass weighed, which affects any concentration calculated from it.
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.
Within a generation, the Norman elite abandoned Old Norse for the Gallo-Romance language that would evolve into Norman French. They also converted to Christianity, but did so while retaining a distinct warrior ethos. This fusion is evident in the popularity of given names; while Old Norse names like Hrólfr (Rollo) and Ansteinn (Osten) were initially common, they were quickly Latinized or replaced by Christian names, yet the martial spirit remained central to their identity. In many ways they would seem "more French than the French". The descendants of Vikings replaced the Norse religion and Old Norse language with Catholicism (Christianity) and the Langue d'oil of the local people, descending from the Latin of the Romans. The Norman language (Norman French) was forged by the adoption of the indigenous langue d'oïl branch of Romance by a Norse-speaking ruling class, and it developed into the French regional languages that survive today. The new Norman rulers were culturally and ethnically distinct from the old French aristocracy, most of whom traced their lineage to the Franks of the Carolingian dynasty from the days of Charlemagne in the 9th century. By intermarrying with the local aristocracy and adopting the growing feudal doctrines of the rest of France, the Normans would progressively work these principles into a functional hierarchical system in their own duchy, and later export it to Norman dominated England. The Norman population outside the Viking settler elite were overwhelmingly locals of West Francia.
==== Labeling ==== For US food and dietary supplement labeling purposes, the amount in a serving is expressed as a percent of Daily Value (%DV). For selenium labeling purposes, 100% of the Daily Value was 70 μg, but as of 27 May 2016 it was revised to 55 μg. A table of the old and new adult daily values is provided at Reference Daily Intake.
Although castration ceases production of androgens by the gonads and reduces circulating testosterone levels by about 95%, low levels of androgens continue to be produced by the adrenal glands, and this accounts for the residual levels of circulating testosterone. Moreover, it has been found that prostate gland levels of DHT, which is the major androgen in the prostate, remain at 40 to 50% of their initial values following castration. This has been determined to be due to uptake of circulating weak adrenal androgens like dehydroepiandrosterone (DHEA) and androstenedione (A4) by the prostate and their de novo transformation into testosterone and DHT. As such, a considerable amount of androgen signaling continues within the prostate gland even with castration. In the past, surgical adrenalectomy and early androgen biosynthesis inhibitors like ketoconazole and aminoglutethimide were successfully employed in the treatment of castration-resistant prostate cancer. However, adrenalectomy is an invasive procedure with high morbidity, ketoconazole and aminoglutethimide have relatively high toxicity, and both treatment modalities require supplementation with corticosteroids, making them in many ways unideal. The development of CAB with NSAAs like bicalutamide and enzalutamide and with newer and more tolerable androgen biosynthesis inhibitors like abiraterone acetate has since allowed for non-invasive, convenient, and well-tolerated therapies that have replaced the earlier modalities.
Sources: en.wikipedia.org
Neuromodulation, whether electrical or magnetic, employs the body's natural biological response by stimulating nerve cell activity that can influence populations of nerves by releasing transmitters, such as dopamine, or other chemical messengers such as the peptide Substance P, that can modulate the excitability and firing patterns of neural circuits. There may also be more direct electrophysiological effects on neural membranes as the mechanism of action of electrical interaction with neural elements. The end effect is a "normalization" of a neural network function from its perturbed state. Presumed mechanisms of action for neurostimulation include depolarizing blockade, stochastic normalization of neural firing, axonal blockade, reduction of neural firing keratosis, and suppression of neural network oscillations. A recent review (2024) has identified relevant etiological hypotheses of non-invasive neuromodulation in different techniques. Data analysis revealed that mitochondrial activity seems to play a central role in different techniques. Analysis of the mother-fetus neurocognitive model provided insights into the conditions of natural neuromodulation of the fetal nervous system during pregnancy.
== Ingredients == As of August 1, 2016, the ingredients within the United States are as follows: White boneless chicken, water, salt, seasoning (yeast extract, salt, wheat starch, natural flavoring, safflower oil, lemon juice solids, dextrose, citric acid), sodium phosphates. Battered and breaded with water, enriched flour (bleached wheat flour, niacin, reduced iron, thiamine mononitrate, riboflavin, folic acid), yellow corn flour, bleached wheat flour, salt, leavening (baking soda, sodium acid pyrophosphate, sodium aluminum phosphate, monocalcium phosphate, calcium lactate), spices, wheat starch, dextrose, corn starch. Prepared in vegetable oil (canola oil, corn oil, soybean oil, hydrogenated soybean oil) with citric acid as a preservative. McDonald's ingredients can vary outside of the US. In August 2016 McDonald's announced that Chicken McNuggets no longer contained artificial preservatives.
=== In model organisms === The E. coli bacterium and S. cerevisiae yeast are two model organisms commonly used for biological study. They are also used as expression systems for producing selenium-substituted proteins, which are used in a form of X-ray crystallography called single- or multi-wavelength anomalous diffraction to determine the tertiary structure of a protein. For these organisms to produce substituted proteins, they are grown in high-selenium environments, which also results in signs of toxicity. Part of this toxicity is due to the random substitution of methionine and cysteine in proteins with the selenium-containing version. Although this is the precise goal of this kind of protein production, alternation of the organism's own proteins in this way can render them nonfunctional.
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.