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 2025-08-03 and is reviewed periodically as new material appears.
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.
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.
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.
Regulatory status differs by country, and in many places supplying the compound for human consumption is unlawful. Vendors frequently label material as intended for research use only, a designation that shifts stated purpose but does not create a legal pathway for personal use. Certificates of analysis accompanying such products vary widely in detail and provenance. Third-party testing exists but is voluntary, and results are rarely linked to a specific lot in a publicly verifiable way.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms differ |
| Molecular weight | Approximately 1024 g/mol | Calculated for the free base |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water and polar solvents | Poorly soluble in non-polar solvents |
| Typical storage | -20 degrees Celsius, dry, protected from light | Refers to the solid form |
Structurally, Melanotan-2 retains the core recognition motif of alpha-melanocyte-stimulating hormone while adding a lactam bridge that links two side chains and constrains the molecule into a ring. This modification lowers susceptibility to enzymatic degradation. The compound acts as an agonist at melanocortin receptors, particularly subtypes associated with melanin production. Because the same receptor family influences several physiological processes, researchers note that its activity is not confined to pigmentation alone. Receptor selectivity continues to be examined in published studies.
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.
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.
Outside regulated medicine, melanotan II circulates through online vendors as a research chemical, often marketed for tanning. Products sold this way vary widely in purity, concentration, and labeling accuracy, and independent testing has documented discrepancies. Published reports describe both pigment effects and adverse reactions, including nausea, flushing, and darkening of existing moles. Long-term safety data are sparse, and no large controlled trial has established a risk profile. Questions about cumulative effects on melanocytes remain unresolved in the literature.
Melanotan II is a synthetic peptide analog modeled on alpha-melanocyte-stimulating hormone, a naturally occurring signaling peptide involved in pigmentation. Its structure is a cyclic heptapeptide containing two non-natural substitutions, norleucine at position four and D-phenylalanine at position seven. These modifications resist enzymatic breakdown and extend the molecule's activity relative to the native hormone. The compound binds melanocortin receptors and is studied mainly as a pharmacological tool rather than a therapeutic product. It has never received approval as a medicine in any major jurisdiction.
=== Israeli−Palestinian conflict === Hitchens described Zionism as "an ethno-nationalist quasi-religious ideology" but argued that Zionism "nonetheless has founded a sort of democratic state which isn't any worse in its practice than many others with equally dubious origins." He stated that Israeli settlements on Palestinian territory to achieve security for Israel are "doomed to fail in the worst possible way", and the cessation of this "appallingly racist and messianic delusion" would "confront the internal clerical and chauvinist forces which want to instate a theocracy for Jews". Hitchens contended that the "solution of withdrawal would not satisfy the jihadists" and wondered "What did they imagine would be the response of the followers of the Prophet [Muhammad]?" Hitchens bemoaned the transference of Arab secularism into religious terrorism as a means of democratisation: "the most depressing and wretched spectacle of the past decade, for all those who care about democracy and secularism, has been the degeneration of Palestinian Arab nationalism into the theocratic and thanatocratic hell of Hamas and Islamic Jihad". On 14 November 2004, Hitchens noted:
Southern Ohio Medical Center (or SOMC) is a 216-bed 501(C)(3) not-for-profit hospital in Portsmouth, Ohio. It provides emergency and surgical care, as well as other health care services. SOMC employs 2,600 full-time employees and part-time employees, has a medical staff of more than 140 physicians and specialists, and is supported by approximately 800 volunteers. In 2020, Fortune magazine ranked Southern Ohio Medical Center at number 22 of their Fortune List of the Top 100 Companies to Work For based on an employee survey of satisfaction.
=== Electrical properties === Most conventional polymers such as polyethylene are electrical insulators, but the development of polymers containing π-conjugated bonds has led to a wealth of polymer-based semiconductors, such as polythiophenes. This has led to many applications in the field of organic electronics.
Belize led to a request for assistance from the International Organization for Migration (IOM) in 2016, which led to the 2018 launch of a national migration policy plan. Most migrants enter Belize with intentions to cross into the US, and as of 2018, migrants made up 15% of Belize's population. Emigration from Belize has tended to be concentrated on the United States, and sometimes Canada or other English-speaking countries. The majority of immigrants to Belize are from other Central American countries like Nicaragua, El Salvador, and Honduras, as Belize has a fairly welcoming immigration policy to help these newcomers assimilate. Belizeans have historically moved to the US and Canada mostly in search of better educational opportunities, family reunions, and economic prospects. Temporary Protected Status (TPS) is a key instrument that has made this trend possible in the US. TPS allows individuals from nations that are undergoing armed conflicts, natural disasters, or extraordinary situations to temporarily stay in the United States. This status has been especially important for Belizeans since Hurricane Hattie in 1961 forced major internal relocation. Belizean immigrants frequently participate in family reunion programs in Canada, which is consistent with the country's larger immigration policy that values social integration and family harmony. Belize's major economic sector is services, making up over 60% of the economy. Nearly 50% of migrants came from Guatemala, and the total composition of the migrants was around 50% men and 49% women.
Sources: en.wikipedia.org
=== Hormone claim retracted === Although the original cytokine function of PBEF has not been confirmed to date, others have since reported or suggested a cytokine-like function for this protein. In particular, Nampt/PBEF was recently re-identified as a "new visceral fat-derived hormone" named visfatin. It is reported that visfatin is enriched in the visceral fat of both humans and mice and that its plasma levels increase during the development of obesity. Noteworthy is that visfatin is reported to exert insulin-mimetic effects in cultured cells and to lower plasma glucose levels in mice by binding to and activating the insulin receptor. However, the physiological relevance of visfatin is still in question because its plasma concentration is 40 to 100-fold lower than that of insulin despite having similar receptor-binding affinity. In addition, the ability of visfatin to bind and activate the insulin-receptor has yet to be confirmed by other groups. On 26 October 2007, A. Fukuhara (first author), I.Shimomura (senior author) and the other co-authors of the paper, who first described Visfatin as a visceral-fat derived hormone that acts by binding and activating the insulin receptor, retracted the entire paper at the suggestion of the editor of the journal 'Science' and recommendation of the Faculty Council of Osaka University Medical School after a report of the Committee for Research Integrity.
Chuck steak is a cut of beef and is part of the sub-prime cut known as the chuck. The typical chuck steak is a rectangular cut, about 2.5 cm (1 inch) thick and containing parts of the shoulder bones of cattle, and is often known as a "7-bone steak," as the shape of the shoulder bone in cross-section resembles the numeral '7'. This cut is usually grilled or broiled; a thicker version is sold as a "7-bone roast" or "chuck roast" and is usually cooked with liquid as a pot roast. The bone-in chuck steak or roast is one of the more economical cuts of beef. In the United Kingdom, this part is commonly referred to as "braising steak". It is particularly popular for use as ground beef for its richness of flavor and balance of meat and fat.
Nicotinamide adenine dinucleotide has several essential roles in metabolism. It acts as a coenzyme in redox reactions, as a donor of ADP-ribose moieties in ADP-ribosylation reactions, as a precursor of the second messenger molecule cyclic ADP-ribose, as well as acting as a substrate for bacterial DNA ligases and a group of enzymes called sirtuins that use NAD+ to remove acetyl groups from proteins. In addition to these metabolic functions, NAD+ emerges as an adenine nucleotide that can be released from cells spontaneously and by regulated mechanisms, and can therefore have important extracellular roles.
In 2008, Cephalon, the manufacturer of Provigil, pleaded guilty to a federal criminal charge related to its promotion of off-label uses of Provigil and two other drugs, paying $425 million in fines and settlements.
Three structural isomers of L-tyrosine are known. In addition to the common amino acid L-tyrosine, which is the para isomer (para-tyr, p-tyr or 4-hydroxyphenylalanine), there are two additional regioisomers, namely meta-tyrosine (also known as 3-hydroxyphenylalanine, L-m-tyrosine, and m-tyr) and ortho-tyrosine (o-tyr or 2-hydroxyphenylalanine), that occur in nature. The m-tyr and o-tyr isomers, which are rare, arise through non-enzymatic free-radical hydroxylation of phenylalanine under conditions of oxidative stress. They are toxic to both animals and plants.
Sources: en.wikipedia.org
{\displaystyle p^{D}(r)={\begin{cases}-{\frac {\sigma _{0}}{\pi }}\cos ^{-1}\left[{\frac {2-m^{2}-{\frac {r^{2}}{a^{2}}}}{m^{2}\left(1-{\frac {r^{2}}{m^{2}a^{2}}}\right)}}\right]&\quad {\text{for}}\quad r\leq a\\-\sigma _{0}&\quad {\text{for}}\quad a\leq r\leq c\end{cases}}}
=== Interaction with drugs === In vitro testing suggests that unidentified wolfberry phytochemicals in goji tea may inhibit metabolism of medications, such as those processed by the cytochrome P450 liver enzymes, including such drugs as warfarin.
=== Available forms === Tazarotene is available in several topical formulations, including gels, creams, foams, and lotions, with concentrations ranging from 0.045% to 0.1%. Tazarotene was first approved in 1997 as a 0.05% and 0.1% gel, followed by 0.05% and 0.1% creams in 2000. In 2012, a 0.1% aerosol foam was introduced to provide easier application to hair-bearing or large surface areas of the skin. A 0.045% lotion was approved in 2019, which utilizes a polymeric emulsion technology to stabilize the active ingredient at a lower concentration with increased absorption. Tazarotene is also available as a fixed-dose combination drug in the topical formulation of halobetasol/tazarotene for use in psoriasis.
== Function == DHX8 is localized in the cellular nucleus and stimulated upon RNA presence. This protein is a component of the spliceosome, so it takes part in pre-mRNA splicing. Splicing is the process of joining exons from primary transcripts of messenger RNA and the elimination of intron sequences, by means of a spliceosomal mechanism, so that the mRNA produced is the one without introns, consisting exclusively of the joined exons. Splicing finishes with the spliceosomal complex disassembly and the ATP-dependent liberation of the resulting mature RNAs to the outer of the nucleus. Spliceosome requires conformational changes to be able to catalyze splicing reactions and the later mature mRNA releasing to the outer of the nucleus. One of the ATP-dependent helicase needed for these conformational changes is DHX8. Furthermore, DHX8 plays a key role in the releasing, facilitating the nuclear export of spliced mRNA. Protein characterization has shown that DHX8 has a binding preference for adenine-rich RNA. This binding is followed by ATP hydrolysis and thus, ADP release.
Sources: en.wikipedia.org
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.
Both are synthetic analogues derived from the same parent hormone. Reference descriptions usually characterise afamelanotide as more selective for the MC1R subtype, whereas melanotan-2 is reported to interact with a wider range of melanocortin receptors.
Early studies explored melanocortin signalling and pigmentation, which later led to informal use of the label tanning peptide. That label is not a regulatory category and does not imply approved status for any purpose.
Dry powder is usually held frozen, shielded from light, and kept away from moisture. Desiccant packaging limits hydrolysis during storage. Solutions are typically aliquoted and frozen once, because repeated thawing shortens useful life.