MC1R is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-02-03. Where a claim depends on a specific study, the study is described rather than over-claimed.
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its structure substitutes a lactam bridge between side chains to increase stability relative to the native hormone. The compound is also known by the shorthand MT-II and by several non-proprietary synonyms used in research catalogues. It is not an approved therapeutic product in any major jurisdiction; material sold under this name is typically offered as a laboratory reagent rather than as a medicine.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analogue of alpha-melanocyte-stimulating hormone |
| Common synonyms | MT-II; melanotan 2 | No internationally accepted non-proprietary name |
| Typical presentation | Lyophilised powder in a sealed vial | Often supplied alongside a separate diluent |
| Regulatory status | Unapproved therapeutic substance | Customs seizure reported in several jurisdictions |
| Reported route in use | Subcutaneous injection | Self-administered outside clinical settings |
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
The peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
=== Neurodegeneration === Pathological protein aggregation is a major hallmark of multiple neurodegenerative diseases. O-GlcNAc on various proteins has been found to play roles in suppressing protein aggregation, motivating clinical efforts to inhibit OGA and elevate cellular O-GlcNAc levels. This strategy is being evaluated by companies for Alzheimer's disease, Parkinson's disease, progressive supranuclear palsy, and amyotrophic lateral sclerosis (ALS). Multiple companies have advanced OGA inhibitors into the clinic including Alectos Therapeutics, Asceneuron, Biogen, Eli Lilly, and Merck.
where the M over the arrow denotes that to conserve energy and momentum a third body is required (the molecularity of the reaction is three). Electron capture can be used in conjunction with chemical ionization. An electron capture detector is used in some gas chromatography systems.
=== Absorption === Absorption refrigerators may be used in caravans and trailers, and dwellings lacking electricity, such as farms or rural cabins, where they have a long history. They may be powered by any heat source: gas (natural or propane) or kerosene being common. Models made for camping and RV use often have the option of running (inefficiently) on 12 volt battery power.
Sources: en.wikipedia.org
While the Leidenfrost temperature is not directly related to the surface tension of the fluid, it is indirectly dependent on it through the film boiling temperature. For fluids with similar thermophysical properties, the one with higher surface tension usually has a higher Leidenfrost temperature. A related phenomenon was observed during the solidification of paraffin wax droplets, which develop a characteristic apple-like shape with a central dimple due to the combined effects of gravity, viscosity increase, and heat conduction through a mushy zone. For example, for a saturated water–copper interface, the Leidenfrost temperature is 257 °C (495 °F). The Leidenfrost temperatures for glycerol and common alcohols are significantly smaller because of their lower surface tension values (density and viscosity differences are also contributing factors.)
The two substrates of this enzyme are estradiol and oxidised nicotinamide adenine dinucleotide (NAD+). Its products are estrone, reduced NADH, and a proton. The enzyme can alternatively use nicotinamide adenine dinucleotide phosphate as its cofactor. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is estradiol-17beta:NAD(P)+ 17-oxidoreductase. Other names in common use include 20alpha-hydroxysteroid dehydrogenase, 17beta,20alpha-hydroxysteroid dehydrogenase, 17beta-estradiol dehydrogenase, estradiol dehydrogenase, estrogen 17-oxidoreductase, and 17beta-HSD. This enzyme participates in androgen and estrogen metabolism.
SUMOplot Analysis Program — predicts and scores SUMOylation sites in your protein (by Abgent) seeSUMO - prediction of SUMOylation sites SUMOsp - prediction of SUMOylation sites JASSA - Predicts and scores SUMOylation sites and SIM (SUMO interacting motif)
Sources: en.wikipedia.org
A notable application of these crystals is the development of quantum dots. Peidong Yang, another researcher from the University of California, Berkeley, is also notable for his contributions to the development of 1-dimensional nanostructures. The Yang group has active research projects in the areas of nanowire photonics, nanowire-based solar cells, nanowires for solar to fuel conversion, nanowire thermoelectrics, nanowire-cell interface, nanocrystal catalysis, nanotube nanofluidics, and plasmonics.
=== Additional Nuclear Forensic Methods === Numerous additional approaches may be employed in the interrogation of seized nuclear material. In contrast to previously mentioned analysis techniques, these approaches have received relatively low attention in recent years in terms of novel advancement, and, typically, require greater quantities of sample.
== Function == NADPH provides the reducing agents, usually hydrogen atoms, for biosynthetic reactions and the oxidation-reduction involved in protecting against the toxicity of reactive oxygen species (ROS), allowing the regeneration of glutathione (GSH). NADPH is also used for anabolic pathways, such as cholesterol synthesis, steroid synthesis, ascorbic acid synthesis, xylitol synthesis, cytosolic fatty acid synthesis and microsomal fatty acid chain elongation. The NADPH system is also responsible for generating free radicals in immune cells by NADPH oxidase. These radicals are used to destroy pathogens in a process termed the respiratory burst. It is the source of reducing equivalents for cytochrome P450 hydroxylation of aromatic compounds, steroids, alcohols, and drugs.
Agarose gel can have high gel strength at low concentration, making it suitable as an anti-convection medium for gel electrophoresis. Agarose gels as dilute as 0.15% can form slabs for gel electrophoresis. The agarose polymer contains charged groups, in particular pyruvate and sulfate. These negatively charged groups can slow down the movement of DNA molecules in a process called electroendosmosis (EEO). Low EEO (LE) agarose is therefore generally preferred for use in agarose gel electrophoresis of nucleic acids. Zero EEO agaroses are also available but these may be undesirable for some applications as they may be made by adding positively charged groups that can affect subsequent enzyme reactions. Electroendosmosis is a reason agarose is used preferentially over agar as agaropectin in agar contains a significant amount of negatively charged sulphate and carboxyl groups. The removal of agaropectin in agarose substantially reduces the EEO, as well as reducing the non-specific adsorption of biomolecules to the gel matrix. However, for some applications such as the electrophoresis of serum protein, a high EEO may be desirable, and agaropectin may be added in the gel used. LE agarose is said to be better for preparative electrophoresis, i.e. when DNA needs to be extracted from an agarose gel.
Sources: en.wikipedia.org
No. No major regulatory agency has granted a marketing authorisation for melanotan II as a medicine. Products sold under this name are generally presented as laboratory reagents and are not subject to the batch-release testing applied to approved drugs.
It was developed in the 1980s by researchers investigating analogues of alpha-melanocyte-stimulating hormone for pigmentation and related endpoints. Early work included small human studies during the 1990s. Development did not progress to licensing, and the compound remained a research and grey-market item.
Peptides are prone to truncation, oxidation and aggregation during synthesis and handling. Without independent testing, a buyer cannot confirm the identity or the content of a vial. Analytical surveys of unapproved peptide products have repeatedly found discrepancies between label claims and measured composition.
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.