This is a working overview of MC1R, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-11-16 and is reviewed periodically as new material appears.
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.
Reported observations after unregulated use include shifts in skin pigmentation and, in some accounts, unintended changes to moles and other lesions. Whether these outcomes are causally linked to the compound, and how often they occur, remain open questions because controlled data are scarce. The absence of standardised dosing and verified product purity complicates interpretation. Researchers have called for better surveillance and analytical characterisation of samples obtained outside regulated channels. Conclusions drawn from anecdotal evidence should be treated as provisional.
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.
| Property | Value | Notes |
|---|---|---|
| Regulatory status | Unapproved for therapeutic use | No marketing authorisation from major agencies |
| Legal classification | Varies by jurisdiction | Prescription-only or controlled in several countries |
| Common synonyms | Melanotan II; MT-II | Also referenced by catalogue codes |
| Typical analytical method | Reverse-phase HPLC | Often paired with mass spectrometry |
| Primary literature focus | Receptor pharmacology | Pigmentation and melanocortin signalling |
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.
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.
Melanotan II is a synthetic cyclic heptapeptide that acts as an agonist at melanocortin receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide involved in pigment production. The analogue carries a lactam bridge that constrains the ring and slows enzymatic breakdown relative to the native hormone. In research literature it appears under several abbreviations, and naming conventions are not fully standardized. Published descriptions usually place it within the broader melanocortin agonist family.
Receptor binding at MC1R on melanocytes raises intracellular cyclic AMP and increases expression of tyrosinase and related enzymes. The downstream result is greater synthesis of eumelanin, the dark pigment, without ultraviolet exposure acting as the trigger. The compound is not selective, however, and also engages MC3R, MC4R and MC5R, which are expressed in the central nervous system and elsewhere. That lack of selectivity is the explanation usually offered for effects reported outside pigmentation, including appetite suppression and nausea. Selectivity remains a central theme in comparative studies of related peptides.
Human data remain limited and mostly short-term. Reports describe small trials and observational accounts rather than large controlled studies, so questions about dose-response relationships and long-term effects on melanocytes stay open. Whether repeated exposure alters naevus behaviour is not settled in the published record. Researchers also note that self-administered use outside clinical settings makes actual exposure difficult to quantify. Statements about efficacy and safety should therefore be read as preliminary rather than established.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, which separates the target peptide from truncated or oxidised impurities. Mass spectrometry, most often coupled to liquid chromatography, confirms molecular mass and detects substitutions that chromatography alone may miss. Amino acid analysis and peptide mapping supply additional structural evidence, while nuclear magnetic resonance is reserved for full structural confirmation. Laboratories that examine samples sold online report wide variation in actual content, with some vials containing little or none of the labelled material.
Melanotan-2 appears on the World Anti-Doping Agency prohibited list within the peptide hormone class, and several national regulators treat it as an unapproved prescription substance. Some countries restrict importation or sale for personal use. Because the compound is widely traded as a research chemical, the practical legal picture differs between jurisdictions and shifts over time. Human safety data covering long periods are limited, and whether repeated pigmentation changes carry any lasting risk to melanocytes remains an open question.
Freeze-dried melanotan-2 is normally kept as a desiccated powder at minus twenty degrees Celsius or lower, shielded from light and moisture. Peptides of this size degrade through hydrolysis, oxidation and deamidation, and each pathway accelerates as temperature and water activity rise. Repeated freeze-thaw cycles promote aggregation and loss of material, so aliquoting a stock solution before freezing is standard laboratory practice. Once dissolved, the solution is markedly less stable than the powder. In laboratory work, solutions are generally refrigerated and used within days rather than kept for months.
== Structure == Alginic acid is a linear copolymer with homopolymeric blocks of (1→4)-linked β-D-mannuronate (M) and α-L-guluronate (G) residues, respectively, covalently linked together in different sequences or blocks. The monomers may appear in homopolymeric blocks of consecutive G-residues (G-blocks), consecutive M-residues (M-blocks) or alternating M and G-residues (MG-blocks). α-L-guluronate is the C-5 epimer of β-D-mannuronate.
He had to leave the game after the seventh with a pulled back muscle, but he was back in action four days later. He won just twice more all season, as he dealt with back problems. On August 1, he again struck out eight Phillies but received a no decision, as he was removed with one out in the ninth and the game tied 1–1. The Cardinals won on a Stan Musial home run in the bottom of the inning. In 31 games (30 starts), he had a 13–10 record, a 4.20 ERA, 108 strikeouts, and 89 walks in 201+1⁄3 innings pitched. By 1960, Mizell had recovered from his back issues. He began the season with the Cardinals but only won one of his first nine games, posting a 4.55 ERA. By this point, the Cardinals felt that he had never attained his full potential. On May 28, they traded him and Dick Gray to the Pirates for Ed Bauta and Julián Javier, the latter of whom would reach two All-Star Games and win two World Series with the Cardinals over the next decade.
silent mutation A type of neutral mutation which does not have an observable effect on the organism's phenotype. Though the term "silent mutation" is often used interchangeably with synonymous mutation, synonymous mutations are not always silent, nor vice versa. Missense mutations which result in a different amino acid but one with similar functionality (e.g. leucine instead of isoleucine) are also often classified as silent, since such mutations usually do not significantly affect protein function.
Sources: en.wikipedia.org
== Sources == Forbes (2014). "Alexander Rich". Profiles. Forbes. Archived from the original on 15 March 2014. Retrieved 15 March 2014. Gen. Eng. Biotechnol. News (February 15, 2014). "BioMarin Nabs Repligen's HDACi Compound Library". News: Discovery & Development. Gen. Eng. Biotechnol. News (paper). Vol. 34, no. 4. p. 14. International New York Times (2014). "Repligen Corporation". Business Day. International New York Times. Company Information. Archived from the original on 15 March 2014. Retrieved 15 March 2014. Motley Fool (2014). "Repligen Corp Key Executives RGEN". The Motley Fool. Archived from the original on 15 March 2014. Retrieved 15 March 2014. "Repligen Corporation, Form 10-K, 2013", SEC Documents, Form 10-K, Repligen, 2014-03-14, Commission File Number 000-14656, retrieved 2026-05-15{{citation}}: CS1 maint: year (link) Street Insider (19 September 2011). "Repligen (RGEN) Replaces Board Member Alex Rich with Alfred Goldberg". Street Insider. Archived from the original on 15 March 2014. Retrieved 15 March 2014.
Pesticides include a wide variety of chemical compounds, used in both agriculture and non-agricultural contexts. Globally, roughly 4,000 chemical compounds are officially registered as being designed for biological activity as pesticides. Pesticides are broadly categorized into plant protection products for countering pests and diseases, and biocidal products such as disinfectants, which may be used domestically to control harmful organisms. Agricultural pesticides are further grouped into herbicides (used against plants), fungicides (used against fungi and spores), and insecticides (against insects). The properties targeted by pesticides are often shared by both the intended targets and other non-target species, including humans. Both those working with pesticides and those living near areas of application are at increased risk. Evidence from epidemiological, animal, and in vitro studies suggests that exposure to pesticides increases the risk for Parkinson's disease. Numerous meta‐analyses and epidemiological studies have reported an increased risk ratio or odds ratio for being exposed to pesticides. PD prevalence is associated with local pesticide use. Length of duration of pesticide exposure is associated with increased PD risk, while high proximity and frequent pesticide exposure are associated with earlier age of onset. Pesticide exposure after diagnosis may accelerate disease progression. Herbicides such as paraquat, diquat, rotenone and glyphosate are the most clearly established environmental toxicants for PD and are likely causal.
"Any substance or combination of substances presented as having properties for treating or preventing disease in human beings; or" "Any substance or combination of substances which may be used in or administered to human beings either with a view to restoring, correcting, or modifying physiological functions by exerting a pharmacological, immunological or metabolic action or to making a medical diagnosis." In the US, a "drug" is:
The successful incorporation of a third base pair is a significant breakthrough toward the goal of greatly expanding the number of amino acids which can be encoded by DNA, from the existing 20 amino acids to a theoretically possible 172, thereby expanding the potential for living organisms to produce novel proteins. In the future, these unnatural base pairs could be synthesised and incorporated into oligonucleotides via DNA printing methods.
Sources: en.wikipedia.org
Several experts called the U.S. airdrops performative and said they would do little to alleviate the famine in Gaza. Biden continued to support Israel during the course of the war despite significant domestic opposition to American involvement in it and subsequent widespread protests. A March 2024 Gallup poll found that a strong majority of Americans disapproved of Israeli conduct during the war. Beginning in April 2024, widespread Gaza war protests emerged on university campuses, denouncing Biden. On May 31, 2024, Biden announced his support for an Israeli ceasefire proposal, saying that Hamas was "no longer capable" of another large-scale attack. The proposal, which was intended to establish a permanent ceasefire, bring about the release of all hostages, and lead to the reconstruction of the Gaza Strip, was supported by Hamas officials after mediation by Egypt and Qatar. The Netanyahu administration responded that Israel's goals regarding "the destruction of Hamas military and governing capabilities" had not changed and that conditions would need to be met before it would agree to a ceasefire. In the first year of the war, it was estimated that the Biden administration had sent Israel at least $17.9 billion in military aid, a record. In about the same period, it sent Palestinians $1.2 billion in humanitarian aid. Biden was reported by journalist Bob Woodward to have clashed throughout the war with Netanyahu over his war strategy and lack of a postwar plan for Gaza.
=== Non-demographic evidence === Evidence for maximum lifespan is also provided by the dynamics of physiological indices with age. For example, scientists have observed that a person's VO2max value (a measure of the volume of oxygen flow to the cardiac muscle) decreases as a function of age. Therefore, the maximum lifespan of a person could be determined by calculating when the person's VO2max value drops below the basal metabolic rate necessary to sustain life, which is approximately 3 ml per kg per minute. On the basis of this hypothesis, athletes with a VO2max value between 50 and 60 at age 20 would be expected "to live for 100 to 125 years, provided they maintained their physical activity so that their rate of decline in VO2max remained constant".
Alex Wayman has argued that the ideas found in the dependent origination doctrine may precede the birth of the Buddha, noting that the first four causal links starting with avidya in the Twelve Nidānas are found in the cosmic development theory of the Brihadaranyaka Upanishad and other older Vedic texts. According to Kalupahana, the concept of causality and causal efficacy where a cause "produces an effect because a property or svadha (energy) is inherent in something" along with alternative ideas of causality, appear extensively in the Vedic literature of the 2nd millennium BCE, such as the 10th mandala of the Rigveda and the Brahmanas layer of the Vedas.
Sources: en.wikipedia.org
Major regulatory agencies have not approved it for any indication. Some countries permit it only under prescription frameworks, while others classify it as a controlled substance.
Much of the evidence comes from case reports and accounts of unregulated use rather than controlled trials. Differences in product purity and dosing add further variability.
Laboratory work focuses on receptor binding and cellular signalling. Observational reports document outcomes after use, and analytical chemists examine samples to assess content and purity.
No. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.