A practical reference on Melanotan II: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-08-06. Anything still debated is marked as such rather than presented as settled.
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.
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 an analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its sequence incorporates modified residues that increase potency and extend biological activity relative to the native hormone. The compound binds receptors of the melanocortin family and is examined mainly in laboratory research. It does not occur naturally and exists only as a manufactured chemical entity produced by solid-phase synthesis.
The peptide was developed during the 1980s by researchers investigating melanocortin signalling and skin pigmentation pathways. Early work focused on analogues of alpha-melanocyte-stimulating hormone that would resist enzymatic breakdown more effectively than the parent molecule. Melanotan-2 emerged from that programme as a shortened, cyclised variant. Reports describing its synthesis and receptor activity later appeared in the scientific literature. Commercial availability grew through unregulated channels rather than through pharmaceutical approval.
| 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, 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.
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its structure substitutes a lactam bridge between side chains to increase stability relative to the native hormone. The compound is also known by the shorthand MT-II and by several non-proprietary synonyms used in research catalogues. It is not an approved therapeutic product in any major jurisdiction; material sold under this name is typically offered as a laboratory reagent rather than as a medicine.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, the naturally occurring peptide involved in pigmentation signalling. Its sequence is conventionally written as Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, with a lactam bridge joining the aspartate side chain to the lysine side chain. The empirical formula is C50H69N15O9 and the monoisotopic mass lies near 1023.5 daltons. N-terminal acetylation and the D-configured phenylalanine both increase resistance to enzymatic breakdown compared with the parent hormone.
Pharmacologically, melanotan-2 behaves as a non-selective agonist across the melanocortin receptor family. Binding at MC1R on dermal melanocytes promotes eumelanin synthesis, which underlies the tanning response described in early human work. Activity at the centrally expressed MC4R receptor is associated with reported effects on appetite and erectile function. Because the peptide does not discriminate strongly among receptor subtypes, attributing any single observed effect to one receptor pathway is generally not possible without selective antagonists or receptor knockout models.
==== Cognitive symptoms ==== Suicidal ideation Susceptibility to cravings Depression Spontaneous orgasm Prolonged insomnia Delirium Auditory hallucinations Visual hallucinations Increased perception of odors (olfaction), real or imagined Marked decrease in sex drive Agitation Anxiety Panic disorder Nervousness Paranoia Delusions Apathy Anorexia (symptom)
== Formation of sugar-carbamino == The sugar-carbamino is formed through a C-glycosidic linkage with the amino acid side chain via various linkers. The synthesis involves introducing annulation to appropriate amino acid residues to rigidify glycopeptides, followed by Diels-Alder cycloadditions to fuse cyclic α- and β-amino acids to the sugar moiety. This also involves the preparation of fused bicyclic C-glycosyl α-amino acid 4, which is confirmed through 2D NMR experiments, particularly NOESY. The approach to conformationally constrained (annulated)-C-glycosyl α- and β-amino acids is based upon the Diels-Alder reaction of pyranose dienes with α- and β-nitro acrylic esters.
As the real world had shown the importance of sulfate aerosol concentrations to the global climate, research into the subject accelerated. Formation of the aerosols and their effects on the atmosphere can be studied in the lab, with methods like ion-chromatography and mass spectrometry Samples of actual particles can be recovered from the stratosphere using balloons or aircraft, and remote satellites were also used for observation. This data is fed into the climate models, as the necessity of accounting for aerosol cooling to truly understand the rate and evolution of warming had long been apparent, with the IPCC Second Assessment Report being the first to include an estimate of their impact on climate, and every major model able to simulate them by the time IPCC Fourth Assessment Report was published in 2007. Many scientists also see the other side of this research, which is learning how to cause the same effect artificially. While discussed around the 1990s, if not earlier, stratospheric aerosol injection as a solar geoengineering method is best associated with Paul Crutzen's detailed 2006 proposal.
Sources: en.wikipedia.org
Amyloid beta can be measured semiquantitatively with immunostaining, which also allows one to determine location. Amyloid beta may be primarily vascular, as in cerebral amyloid angiopathy, or in amyloid plaques in white matter. One sensitive method is ELISA which is an immunosorbent assay which utilizes a pair of antibodies that recognize amyloid beta. Atomic force microscopy, which can visualize nanoscale molecular surfaces, can be used to determine the aggregation state of amyloid beta in vitro. Vibrational microspectroscopy is a label-free method that measures the vibration of molecules in tissue samples. Amyloid proteins like Aβ can be detected with this technique because of their high content of β-sheet structures. Dual polarisation interferometry is an optical technique which can measure early stages of aggregation by measuring the molecular size and densities as the fibrils elongate. These aggregate processes can also be studied on lipid bilayer constructs. TPM21 Sylvain Lesné – Aβ*56 Online Mendelian Inheritance in Man (OMIM): 104300
There are three known stable isotopes of oxygen (8O): 16O, 17O, and 18O. Radioisotopes are known from 11O to 28O (particle-bound from mass number 13 to 24), and the most stable are 15O with half-life 122.27 seconds and 14O with half-life 70.62 seconds. All remaining radioisotopes are even shorter in lifetime. The four heaviest known isotopes (up to 28O) decay by neutron emission to 24O, whose half-life is 77 milliseconds; 24O, along with 28Ne, have been used in the model of reactions in the crust of neutron stars. The most common decay mode for isotopes lighter than the stable isotopes is β+ decay to nitrogen, and the most common mode after is β− decay to fluorine.
As menin is located predominantly in the nucleus, these mutations can impact the stability of the cell and may further affect functional activity or expression levels of the protein. Studies have also shown that single amino acid changes in genes involved in oncogenic disorders may result in proteolytic degradation leading to loss of function and reduced stability of the mutant protein; a common mechanism for inactivating tumor suppressor gene products. MEN1 gene mutations and deletions also play a role in the development of hereditary and a subgroup of sporadic pituitary adenomas and were detected in approximately 5% of sporadic pituitary adenomas. Consequently, alterations of the gene represent a candidate pathogenetic mechanism of pituitary tumorigenesis especially when considered in terms of interactions with other proteins, growth factors, oncogenes play a rule in tumorigenesis. Although the exact function of MEN1 is not known, the Knudson "two-hit" hypothesis provides strong evidence that it is a tumor suppressor gene. Familial loss of one copy of MEN1 is seen in association with MEN-1 syndrome. Tumor suppressor carcinogenesis follows Knudson's "two-hit" model. The first hit is a heterozygous MEN1 germline mutation either developed in an early embryonic stage and consequently present in all cells at birth for the sporadic cases, or inherited from one parent in a familial case. The second hit is a MEN1 somatic mutation, oftentimes a large deletion occurring in the predisposed endocrine cell and providing cells with the survival advantaged needed for tumor development.
Sources: en.wikipedia.org
== Biochemistry == 2-Aminomuconic semialdehyde is an intermediate in the kynurenine pathway of tryptophan metabolism, which leads to picolinic acid or quinolinic acid. The enzyme aminocarboxymuconate-semialdehyde decarboxylase produces it from 2-amino-3-carboxymuconic semialdehyde, a compound which would form quinolinic acid in the absence of that enzyme.
In the 1984 presidential election, SPUSA nominated the Citizens Party candidate for president, Sonia Johnson. In the 2020 presidential election, the SPUSA nominated the Green Party nominee Howie Hawkins for president. Hawkins also received various state-level party endorsements, such as the Liberty Union Party in Vermont, in a bid to unite the "non-sectarian independent Left" behind a single campaign.
== History and name == The name leukotriene, introduced by Swedish biochemist Bengt Samuelsson in 1979, comes from the words leukocyte and triene (indicating the compound's three conjugated double bonds). What would be later named leukotriene C, "slow reaction smooth muscle-stimulating substance" (SRS) was originally described between 1938 and 1940 by Feldberg and Kellaway. The researchers isolated SRS from lung tissue after a prolonged period following exposure to snake venom and histamine.
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.
It is a synthetic cyclic heptapeptide and an analogue of alpha-melanocyte-stimulating hormone. The molecule is produced by chemical synthesis rather than extracted from a biological source.