Everything below concerns melanocortin receptor. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-01-13. 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.
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.
The compound emerged from research programs in the 1980s that examined analogues of alpha-melanocyte-stimulating hormone for pigmentation and photoprotection. Investigators modified the native sequence to extend activity duration and potency. A related analogue, afamelanotide, was developed within the same broad line of inquiry and eventually gained approval in certain jurisdictions for a rare light-sensitivity condition. Melanotan-2 itself did not progress through the same regulatory route and has no approved therapeutic indication.
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.
| 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, 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.
Research interest has centred on photoprotection and pigmentation, with a smaller body of work on appetite and sexual function. Published human data remain limited to small, frequently uncontrolled studies, and the compound has never received marketing approval from a national medicines regulator. Most laboratory work treats it as a pharmacological tool for probing melanocortin signalling in cell culture or animal models. Whether pigmentation changes observed in people translate into measurable protection against ultraviolet-induced DNA damage remains an open question.
== Role in protection against oxidative stress == Aerobic bacteria inevitably are prone to the formation of reactive oxygen species due to the nature of their respiration processes. Under normal conditions these ROS strive to maintain a dynamic balance; however, this balance can often be disrupted by biotic or abiotic stressors such as superoxide radicals, endogenous lipids, DNA hydroperoxides, hydrogen peroxide, hydroxyl radicals, and hydroxy alkenals. Therefore, these susceptible organisms have intrinsic mechanisms to protect from oxidative damage; glutathione plays a key role in most of these antioxidant mechanisms. Once reduced, glutathione interacts with these reactive oxygen and nitrogen species. This interaction is catalyzed by GSTs and their involvement is vital for successful oxidation of glutathione. GSTs bind the ROS substrate at its hydrophobic alpha-helical C-terminal domain, as well as reduced glutathione to its glutathione-binding site on the N-terminal domain. These two domains are adjacent to each other on the enzyme, and together form the active site of the GST where the redox reaction occurs. Once both substrates are bound at the enzyme's active site, the monomeric GST interacts with another substrate-bound GST monomer and catalyzes a disulphide bridge between the two glutathione molecules. This yields the active dimeric enzyme structure. The reactive oxygen species then donates one electron to a glutathione molecule, completing the oxidation-reduction reaction and rendering it unable to perform oxidative damage to the cell.
5-HT2 receptors are G protein-coupled receptors that can regulate cellular signaling in the absence of a ligand. This can be explained by a two-state model (Figure 2) where the receptor is in equilibrium between two states, an active state (R*) and an inactive state (R). Basal effector activity is defined, in part, by the absolute level of (R*), which will increase along with increasing receptor density. Ligands that preferentially bind to and stabilize the R state are termed inverse agonists and reduce the effector activity. Agonists preferentially bind to and stabilize the R* state, thereby increasing effector activity. Neutral antagonists show equal affinity for both conformations and do not alter the equilibrium between the two states, however they occupy the receptor and can block the effect of both agonists and inverse agonists. 5-HT2C and 5-HT2A receptors have a similar amino acid sequence homology, with ~50% overall sequence identity and ~80% within the TM domains, resulting in a similar pharmacological profile for the two receptors. Both receptors couple the same cellular signal transduction pathways, PLC and PLA2, that lead to an accumulation of inositol phosphate and Ca2+ within the postsynaptic cell. The 5-HT2C receptors are the only G-protein coupled receptors known to undergo a post-transcriptional process of RNA editing. The 5-HT2C receptor gene is found on the X-chromosome, Xq24. This gene product undergoes an RNA editing process leading to a decrease in agonist binding affinity, however antagonist binding remains unaltered.
Days later, the Treasury released £12,300 for further development, and a small team of the RRS researchers were sworn to secrecy and began developing the concept. A system was to be built at the RRS station, and then moved to Orfordness for over-water testing. Wilkins would develop the receiver based on the GPO units, along with suitable antenna systems. This left the problem of developing a suitable pulsed transmitter. An engineer familiar with these concepts was needed.
Sources: en.wikipedia.org
Smaller communities of Hokkien speakers also existed, and many villages hosted more than one ethnolinguistic group. Today, communities of speakers of other Chinese varieties (such as Teochew, Sze Yap, Hokkien, and Shanghainese) also live in Hong Kong. Southeast Asian languages such as Tagalog and Malay-Indonesian speaking communities also live in Hong Kong. Other minority languages with significant speaker bases in Hong Kong include French, Dutch, German, Italian, Spanish, Portuguese, Arabic, Hindustani, Japanese, and Korean, among others.
Medication includes folate supplementation, iron chelation, bisphosphonates, and removal of the spleen. Beta thalassemia can also be treated by bone marrow transplant from a well matched donor, or by gene therapy. Thalassemias were first identified in severely sick children in 1925, with identification of alpha and beta subtypes in 1965. Beta-thalassemia tends to be most common in populations originating from the Mediterranean, the Middle East, Central and Southeast Asia, the Indian subcontinent, and parts of Africa. This coincides with the historic distribution of Plasmodium falciparum malaria, and it is likely that a hereditary carrier of a gene for beta-thalassemia has some protection from severe malaria. However, because of population migration, β-thalassemia can be found around the world. In 2005, it was estimated that 1.5% of the world's population are carriers and 60,000 affected infants are born with the thalassemia major annually.
3'-end Also three-prime end. One of two ends of a single linear strand of DNA or RNA, specifically the end at which the chain of nucleotides terminates at the third carbon atom in the furanose ring of deoxyribose or ribose (i.e. the terminus at which the 3' carbon is not attached to another nucleotide via a phosphodiester bond; in vivo, the 3' carbon is often still bonded to a hydroxyl group). By convention, sequences and structures positioned nearer to the 3'-end relative to others are referred to as downstream. Contrast 5'-end.
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.
No. Melanotan-2 is manufactured synthetically. The naturally occurring peptide in the same family is alpha-melanocyte-stimulating hormone, which the body produces as part of normal endocrine and neural signalling.