A practical reference on MC1R: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-07-02 and is reviewed periodically as new material appears.
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 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.
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.
| 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 II is a synthetic cyclic heptapeptide analog derived from the core sequence of alpha-melanocyte-stimulating hormone. Researchers at the University of Arizona synthesized it during the 1980s while studying pigmentation and appetite signaling. The compound is not an approved medicine in any major jurisdiction and appears mainly in laboratory and research-chemical settings. Its structure incorporates a lactam bridge between side chains, which constrains the ring and slows enzymatic breakdown relative to the natural hormone.
Melanotan II binds several melanocortin receptor subtypes rather than a single target. MC1R on melanocytes drives melanin synthesis, while MC3R and MC4R participate in energy balance, appetite, and sexual response pathways. This lack of selectivity explains why reported effects extend beyond skin darkening. Substitutions at positions four and seven, including norleucine and D-phenylalanine, increase potency and resistance to peptidases. Understanding which receptor mediates which effect remains an active area of investigation.
Published human data come mostly from small, short studies rather than large controlled trials. Reported outcomes include increased skin pigmentation and, in some reports, effects on appetite and libido, but sample sizes are small and follow-up is limited. Whether long-term use produces durable pigment changes or adverse effects is not established. Because products sold outside pharmacies are not standardized, the actual content of any given vial is often unknown. Independent testing of such material is uncommon.
Identity testing for a synthetic peptide relies on several complementary methods. Reversed-phase high-performance liquid chromatography separates the target from related impurities and reports purity as a percentage of total peak area. Mass spectrometry confirms molecular mass and can reveal deletions or truncations. Amino acid analysis and peptide mapping provide sequence-level confirmation, while counter-ion content and residual solvents are measured separately. A purity figure alone does not establish identity, so a complete dataset combines chromatographic and spectrometric evidence.
Lyophilized peptide powder is generally stored frozen, protected from light and moisture. Tryptophan residues are susceptible to oxidation, and the lactam bridge can hydrolyze under strongly acidic or basic conditions. Solutions prepared for laboratory work degrade faster than dry powder, and repeated freeze-thaw cycles accelerate loss. Common practice is to aliquot solutions before freezing and to avoid alkaline buffers. Reported stability windows vary with concentration, buffer, and temperature, so exact shelf lives are method-specific rather than universal.
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.
== History == The concept of validation was first proposed by two Food and Drug Administration (FDA) officials, Ted Byers and Bud Loftus, in 1979 in USA, to improve the quality of pharmaceuticals. It was proposed in direct response to several problems in the sterility of large volume parenteral market. The first validation activities were focused on the processes involved in making these products, but quickly spread to associated processes including environmental control, media fill, equipment sanitization and purified water production. The concept of validation was first developed for equipment and processes and derived from the engineering practices used in delivery of large pieces of equipment that would be manufactured, tested, delivered and accepted according to a contract The use of validation spread to other areas of industry after several large-scale problems highlighted the potential risks in the design of products. The most notable is the Therac-25 incident. Here, the software for a large radiotherapy device was poorly designed and tested. In use, several interconnected problems led to several devices giving doses of radiation several thousands of times higher than intended, which resulted in the death of three patients and several more being permanently injured. In 2005 an individual wrote a standard by which the transportation process could be validated for cold chain products.
=== Expansion and acquisition === By 1997, Reddy's made the transition from being an API and bulk drug supplier to regulated markets like the US and the UK, and a branded formulations supplier in unregulated markets like India and Russia, into producing generics, by filing an Abbreviated New Drug Application (ANDA) in the USA. The same year, Reddy's out-licensed a molecule for clinical trials to Novo Nordisk, a Danish pharmaceutical company. It strengthened its Indian manufacturing operations by acquiring American Remedies Ltd. in 1999. This acquisition made Reddy's the third largest pharmaceutical company in India, after Ranbaxy and Glaxo (I) Ltd., with a full spectrum of pharmaceutical products, which included bulk drugs, intermediates, finished dosages, chemical synthesis, diagnostics and biotechnology. Reddy's also started exploiting Para 4 filing as a strategy in bringing new drugs to the market at a faster pace. In 1999 it submitted a Para 4 application for omeprazole, the drug that had been the cornerstone of its success in India. In December 2000, Reddy's had undertaken its first commercial launch of a generic product in the US, and its first product with market exclusivity was launched there in August 2001. The same year, it also became the first non-Japanese pharmaceutical company from the Asia-Pacific region to obtain a New York Stock Exchange listing. In 2001 Reddy's became the first Indian company to launch the generic drug, fluoxetine (a generic version of Eli Lilly and Company’s Prozac) with 180-day market exclusivity in the USA.
"Handout on Health: Back Pain". National Institute of Arthritis and Musculoskeletal and Skin Diseases. 10 April 2017. Qaseem A, Wilt TJ, McLean RM, Forciea MA (April 2017). "Noninvasive Treatments for Acute, Subacute, and Chronic Low Back Pain: A Clinical Practice Guideline From the American College of Physicians". Annals of Internal Medicine. 166 (7): 514–30. doi:10.7326/M16-2367. PMID 28192789. "Non-specific Back Pain Guidelines" (PDF). Kaiser Foundation Health Plan of Washington. 2017. Archived from the original (PDF) on 14 January 2020.
Sources: en.wikipedia.org
The list contains recommendations for 523 medications. A separate list for children up to twelve years of age, known as the WHO Model List of Essential Medicines for Children (EMLc), was created in 2007, and is in its 10th edition. It was created to make sure that the needs of children were systematically considered such as availability of proper formulations. Everything in the children's list is also included in the main list. The list and notes are based on the 19th to 24th edition of the main list. Therapeutic alternatives with similar clinical performance are listed for some medicines and they may be considered for national essential medicines lists. The 10th Essential Medicines List for Children was updated in September 2025. Note: An α indicates a medicine is on the complementary list.
The electron transport chain carries both protons and electrons, passing electrons from donors to acceptors, and transporting protons across a membrane. These processes use both soluble and protein-bound transfer molecules. In the mitochondria, electrons are transferred within the intermembrane space by the water-soluble electron transfer protein cytochrome c. This carries only electrons, and these are transferred by the reduction and oxidation of an iron atom that the protein holds within a heme group in its structure. Cytochrome c is also found in some bacteria, where it is located within the periplasmic space. Within the inner mitochondrial membrane, the lipid-soluble electron carrier coenzyme Q10 (Q) carries both electrons and protons by a redox cycle. This small benzoquinone molecule is very hydrophobic, so it diffuses freely within the membrane. When Q accepts two electrons and two protons, it becomes reduced to the ubiquinol form (QH2); when QH2 releases two electrons and two protons, it becomes oxidized back to the ubiquinone (Q) form. As a result, if two enzymes are arranged so that Q is reduced on one side of the membrane and QH2 oxidized on the other, ubiquinone will couple these reactions and shuttle protons across the membrane. Some bacterial electron transport chains use different quinones, such as menaquinone, in addition to ubiquinone. Within proteins, electrons are transferred between flavin cofactors, iron–sulfur clusters and cytochromes. There are several types of iron–sulfur cluster.
John Lewis & Partners announce further cuts to the number of its staff over the coming five years, with The Guardian reporting up to 11,000 jobs could go. The British Association of Dermatologists warns against the use of skincare products by children as young as eight, saying that to do so could leave them with irreversible skin damage. 28 January The hottest UK temperature in January is provisionally recorded by the Met Office, with a peak of 19.6 °C (67.3 °F) at Kinlochewe, Scottish Highlands, more than a degree higher than the previous record in 2003. The UK government announces plans to ban disposable vapes in an attempt to tackle the growing number of children taking up vaping. 29 January The King and the Princess of Wales are both discharged from hospital. Laurence Fox loses a High Court libel case with social media users he called paedophiles. Reporting on cases in family courts in England and Wales is extended to a further 16 venues following a trial at three locations. A University College London study of five cases of Alzheimer's disease suggests they could have been caused by a treatment in which the patients were injected with growth hormones from dead people, a treatment that was withdrawn in the mid-1980s. 30 January Lucy Letby has her initial request for permission to appeal against seven murder convictions and six attempted murder convictions refused by the Court of Appeal. HSBC is fined £57.4m by the Bank of England for "serious failings" over its measures to protect customer deposits.
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.
Purity is normally stated as an area percentage from high-performance liquid chromatography, for example ninety-five or ninety-eight percent. That figure describes the proportion of ultraviolet-absorbing material eluting as the main peak. It says nothing about water content, counterions, residual solvents or mass fraction of the peptide itself.