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 2025-12-17 and is reviewed periodically as new material appears.
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.
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.
Identification in laboratories relies on reversed-phase liquid chromatography coupled with tandem mass spectrometry, with product-ion spectra compared against a certified reference standard. High-resolution mass spectrometry supplies accurate mass confirmation, and peptide mapping after enzymatic digestion separates melanotan II from closely related analogues. Quantitation of seized material is complicated by unknown counter-ions and residual trifluoroacetate left from purification. Immunoassays raised against alpha-melanocyte-stimulating hormone can cross-react, so chromatographic confirmation is normally required. Urinary detection windows are short, and reported limits of detection differ substantially between laboratories.
Melanotan II holds no marketing authorisation from the Food and Drug Administration, the European Medicines Agency, the UK Medicines and Healthcare products Regulatory Agency or Australia's Therapeutic Goods Administration. Products sold under that name are treated as unapproved new drugs, and their sale or import is prohibited in several jurisdictions. Other countries classify the peptide as a prescription-only medicine or place it among controlled substances, so the legal position changes with the destination market. No pharmacopoeial monograph supplies an official specification, because the material is not a licensed pharmaceutical. Consequently, products offered online are not manufactured to a shared public standard.
The peer-reviewed record is dominated by small early-phase studies, case reports and pharmacovigilance summaries rather than large randomised trials. Papers typically examine tanning response, receptor selectivity or patterns of reported adverse events. Many note that participants obtained the peptide outside a clinical setting, which limits verification of composition and administered amount. Reported events vary widely, and causality is frequently unclear because the identity and purity of self-sourced material are unknown. Open questions include whether repeated melanocortin receptor stimulation produces cumulative effects, and how often label claims match actual content.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analog of alpha-melanocyte-stimulating hormone |
| Primary receptor family | Melanocortin receptors MC1R through MC5R | Binding is not subtype-selective |
| Development period | 1980s | Synthesized during pigmentation and appetite research |
| Regulatory status | Not an approved medicine | No major regulator has authorized human use |
| Related compound | Afamelanotide | Linear analog studied for photoprotection |
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.
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.
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.
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 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.
== I == IAES – Ion induced Auger electron spectroscopy IBA – Ion beam analysis IBIC – Ion beam induced charge microscopy ICP-AES – Inductively coupled plasma atomic emission spectroscopy ICP-MS – Inductively coupled plasma mass spectrometry Immunofluorescence ICR – Ion cyclotron resonance IETS – Inelastic electron tunneling spectroscopy IGA – Intelligent gravimetric analysis IGF – Inert gas fusion IIX – Ion induced X-ray analysis, see particle induced X-ray emission INS – Ion neutralization spectroscopy Inelastic neutron scattering IRNDT – Infrared non-destructive testing of materials IRS – Infrared spectroscopy ISS – Ion scattering spectroscopy ITC – Isothermal titration calorimetry IVEM – Intermediate voltage electron microscopy
The three substrates of this enzyme are crotonic acid, reduced nicotinamide adenine dinucleotide (NADH), and a proton. Its products are butyric acid and oxidised NAD+. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-CH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is butanoate:NAD+ Delta2-oxidoreductase. This enzyme is also called enoate reductase. This enzyme participates in phenylalanine metabolism. It has cofactors: flavin adenine dinucleotide and iron–sulfur protein.
Protein Expression and Purification is a peer-reviewed scientific journal covering biotechnological research on protein production and isolation based on conventional fractionation as well as techniques employing various molecular biological procedures to increase protein expression.
Ancient Chinese legend holds that a man named Lao Ai had the largest penis in history and that he had an affair with Queen Dowager Zhao (c. 280–228 BC), the mother of Qin Shi Huang, by pretending to be a eunuch. Ancient Koreans admired large penises and King Jijeung (437–514 AD) of the Silla Dynasty is said to have had a forty-five-centimeter penis that was so large his subordinates had to search for a woman that fit him. Traditional Japanese erotic paintings usually show genitals as exaggeratedly large. The oldest known painting of this type, found in the Hōryū-ji Temple in Ikaruga, dates to the eighth century AD and depicts a fairly large penis.
=== Thermal === Thermal FFF, as the name suggests, establishes a separation force by applying a temperature gradient to the channel. The top channel wall is heated and the bottom wall is cooled driving polymers and particles towards the cold wall by thermal diffusion. Thermal FFF was developed as a technique for separating synthetic polymers in organic solvents. Thermal FFF is unique amongst FFF techniques in that it can separate macromolecules by both molar mass and chemical composition, allowing for the separation of polymer fractions with the same molecular weight. Today this technique is ideally suited for the characterization of polymers, gels and nanoparticles. One of the major advantage of thermal FFF is the simple and very well defined dimensions of the separation channel, which makes the inter-lab or inter-instrument universal calibration possible because the thermal FFF calibration constants closely describe the ratio of ordinary (molecular) diffusion coefficient D to thermal diffusion coefficient (or, thermophoretic mobility) DT which are only polymer dependent. The ThFFF universal calibration is, therefore, instrument and lab transferable, while the well-known size exclusion chromatography universal calibration is polymer-transferable on the same instrument only.
Sources: en.wikipedia.org
== Isolation of stem cells protocol == After obtaining the umbilical cord from the donor, it is transported to the laboratory in a cold and sterile environment using a transfer buffer that contains phosphate buffered saline (PBS). Subsequently, the vessels should be eliminated from the umbilical cord tissue on a sterile plate with the aid of autoclaved scissors. The sections of the umbilical cord tissue that are devoid of arteries should then be fragmented into smaller fragments. These tissue fragments are subsequently placed in a sterile cell culture plate or cell culture flask, and the cell culture medium (enriched with fetal bovine serum and antibiotics) is added. Lastly, the flask containing the tissue fragments is placed in a CO2 incubator for a duration of 1-2 weeks. This process ultimately leads to the proliferation and migration of stem cells from the Wharton's jelly into the plate or flask.
==== Rate of sickle cell disease in Uganda ==== The data compiled on sickle cell disease in Uganda has not been updated since the early 1970s. The deficiency of data is due to a lack of government research funds, even though Ugandans die daily from sickle cell disease. Data shows that the trait frequency of sickle cell disease is 20% of the population in Uganda. It is also estimated that about 25,000 Ugandans are born each year with sickle cell disease and 80% of those people do not live past five years old. Sickle cell disease also contributes 25% to the child mortality rate in Uganda. The Bamba people of Uganda, located in the southwest of the country, carry 45% of the gene, which is the highest trait frequency recorded in the world. The Sickle Cell Clinic in Mulago is the only sickle cell disease clinic in the country and, on average, sees 200 patients a day.
Amitay (1958), lobbyist, former executive director of the American Israel Public Affairs Committee and vice chairman of the Jewish Institute for National Security Affairs Richard Grossman (1965), critic and organizer against corporate power, former director of Greenpeace USA Brian Flanagan (1968), former member of the Students for a Democratic Society and Weather Underground David Gilbert (1966), leader of Students for a Democratic Society and participant in the deadly 1981 Brink's robbery with Kathy Boudin, the mother of his child Chesa Boudin Ted Gold* (1968), student activist, leader of the Students for a Democratic Society and member of the Weatherman group who died in the 1970 Greenwich Village townhouse explosion John Jacobs (1969), student activist, member of Students for a Democratic Society and the Weather Underground, went into hiding after the fatal 1970 Greenwich Village townhouse explosion Mark Rudd (1969), president of Students for a Democratic Society and member of the Weather Underground Stephen Donaldson (1970), bisexual political activist, founder of the Student Homophile League at Columbia, the oldest college LGBTQ organization in the world David Kaczynski (1970), anti-death penalty activist, brother of Unabomber Theodore Kaczynski Robert Roth* (1970), activist associated with the Students for a Democratic Society Sheena Wright (1990), CEO of the United Way of New York City David Kaiser (1991), philanthropist, environmental activist, president of the Rockefeller Family Fund, great-great-grandson of John D.
Similar to other species of spider, a hard exoskeleton coats the bodies of P. phalangioides. Depending on the age of the spider, this exoskeleton must be shed at differing intervals; younger spiders tend to molt much more often. During molting, the spider will produce certain enzymes that release the rest of its body from the underlying tissue of its exoskeleton. The spider is then able to escape the exoskeleton. The remnant outer skin or exoskeleton is known as the exuviae. It takes about one year for these spiders to mature after they are born, and their life span is up to two years or more post-maturity.
Sources: en.wikipedia.org
No regulator in a major market has approved it for human use. It appears in research settings and in products marketed outside pharmacy channels. Legal status for personal possession varies by country.
Afamelanotide is a linear analog that has received approval in some jurisdictions for a specific photoprotection indication. Melanotan II is cyclic and less selective across melanocortin receptors. The two are related but are not interchangeable in regulatory or clinical terms.
A compound that activates several receptor subtypes may produce effects beyond pigmentation. Selectivity influences which tissues respond and shapes the side-effect profile described in reports. Designing subtype-selective analogs is a stated goal of melanocortin research.
Regulatory treatment varies by country. In the United States, the European Union and Australia it is an unapproved drug and its sale is restricted, while some other jurisdictions list it as prescription-only or controlled. The applicable rules depend on the country of import.