A practical reference on melanocortin receptors: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-04-06. Anything still debated is marked as such rather than presented as settled.
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
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.
Research interest has centred on photoprotection and pigmentation, with a smaller body of work on appetite and sexual function. Published human data remain limited to small, frequently uncontrolled studies, and the compound has never received marketing approval from a national medicines regulator. Most laboratory work treats it as a pharmacological tool for probing melanocortin signalling in cell culture or animal models. Whether pigmentation changes observed in people translate into measurable protection against ultraviolet-induced DNA damage remains an open question.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, the naturally occurring peptide involved in pigmentation signalling. Its sequence is conventionally written as Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, with a lactam bridge joining the aspartate side chain to the lysine side chain. The empirical formula is C50H69N15O9 and the monoisotopic mass lies near 1023.5 daltons. N-terminal acetylation and the D-configured phenylalanine both increase resistance to enzymatic breakdown compared with the parent hormone.
Pharmacologically, melanotan-2 behaves as a non-selective agonist across the melanocortin receptor family. Binding at MC1R on dermal melanocytes promotes eumelanin synthesis, which underlies the tanning response described in early human work. Activity at the centrally expressed MC4R receptor is associated with reported effects on appetite and erectile function. Because the peptide does not discriminate strongly among receptor subtypes, attributing any single observed effect to one receptor pathway is generally not possible without selective antagonists or receptor knockout models.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Cyclic heptapeptide, C-terminally amidated |
| Approximate molecular mass | 1024 Da | Monoisotopic mass of the free peptide |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility class | Soluble in water and polar solvents | Also dissolves in neutral aqueous buffer |
| Common synonyms | Melanotan II, MT-II, MT-2 | Described as a melanocortin agonist in early literature |
The esophagus (American English) or oesophagus (British English) ( ), also known as the gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the stomach. The esophagus is a fibromuscular tube, about 25 cm (10 in) long in adult humans, that travels behind the trachea and heart, passes through the diaphragm, and empties into the uppermost region of the stomach. During swallowing, the epiglottis tilts backwards to prevent food from going down the larynx and lungs. The word esophagus is from Ancient Greek οἰσοφάγος (oisophágos), from οἴσω (oísō), future form of φέρω (phérō, "I carry") + ἔφαγον (éphagon, "I ate"). The wall of the esophagus from the lumen outwards consists of mucosa, submucosa (connective tissue), layers of muscle fibers between layers of fibrous tissue, and an outer layer of connective tissue. The mucosa is a stratified squamous epithelium of around three layers of squamous cells, which contrasts to the single layer of columnar cells of the stomach. The transition between these two types of epithelium is visible as a zig-zag line. Most of the muscle is smooth muscle although striated muscle predominates in its upper third. It has two muscular rings or sphincters in its wall, one at the top and one at the bottom. The lower sphincter helps to prevent reflux of acidic stomach content. The esophagus has a rich blood supply and venous drainage.
== Treatment == There is no distinct treatment option that can undo the effects and damage from rhabdomyolysis because it is a type of necrosis, where the tissue and body cells die prematurely. However, the rate of the pathology that can lead to more complications can be decreased by acting early and consistently. Overall treatment depends on preventing kidney failure (renal failure) which is done by rehydrating the patient. It also depends on making urine have a more basic pH (alkalinization of urine).
Despite this legal authorization, many cross-border dairy processors supplying both the UK and EU markets have phased out the additive to maintain single, unified manufacturing lines. To maintain the bright profile desired by consumers without using E171, European manufacturers increasingly utilize alternative whitening agents. The most common substitute is calcium carbonate (E170), which is added to food dressings to achieve opacity without the use of unregulated nanoparticles.
Cardio-arrhythmia is a common side effect of diabetic patients and the anti-inflammatory effects of gingerol suppressed the risks by lowering blood glucose levels in-vivo. The anti-oxidant properties of [6]-gingerol has been considered as a defense against Alzheimer’s. A study observed the molecular mechanisms responsible for the protection against DNA fragmentation and mitochondrial membrane potential deterioration of cells which suggests a neuroprotective support of gingerol. This study indicates that ginger up-regulates glutathione production in cells, including nerve cells, through anti-oxidative properties which decreases the risk of Alzheimer's in human neuroblastoma cells and mouse hippocampal cells. While many studies suggest the low risk of using ginger phytochemicals to combat oxidation damage to cells, there are a few studies that suggest potential genotoxic effects. In one study too high of a dose to human hepatoma cells resulted in DNA fragmentation, chromosomal damage and organelle membrane instability which could result in apoptotic behavior. There are some pro-oxidant behaviors to gingerol compounds when the concentration reaches high levels although also considered, in normal conditions these phytochemicals observed have anti-inflammatory and anti-oxidant qualities. In another study [6]-Gingerol notably inhibited the metabolic rate of rats when given an intraperitoneal injection which induced a hypothermic reaction though, when consumed orally in excess there were no changes in body temperature.
== Kinetics of isoaspartyl formation == Isoaspartyl formation reactions have been conjectured to be one of the factors that limit the useful lifetime of proteins. Isoaspartyl formation proceeds much more quickly if the asparagine is followed by a small, flexible residue (such as Gly) that leaves the peptide group open for attack. These reactions also proceed much more quickly at elevated pH (>10) and temperatures.
Sources: en.wikipedia.org
== Clinical significance == The epithelium of the glans penis consists of mucosal tissue. Birley et al. report that excessive washing with soap may dry the mucous membrane which covers the glans penis and cause non-specific dermatitis. The condition is described as an inflammation of the skin, often caused by an irritating substance or a contact allergy. Sensitivity to chemicals in certain products can cause an allergic reaction, including irritation, itching and rash. Inflammation of the glans penis is known as balanitis. It is a treatable condition that occurs in about 3–11% of males (up to 35% of diabetic males). Edwards reported that it is generally more common in males who have poor hygiene habits or have not been circumcised. It has many causes, including irritation or infection with a wide variety of pathogens. Symptoms of balanitis may appear suddenly or develop gradually. They might include pain, irritation, redness or red patches on the glans penis. Careful identification of the cause with the aid of patient history, physical examination, swabs and cultures, and biopsy are essential in order to determine the proper treatment. The meatus (opening) of the urethra located at the tip of the glans might become subject to meatal stenosis, a condition mostly seen as a late complication of circumcision. It occurs in about 2–20% of circumcised boys and it is rarely seen in uncircumcised men. It is characterized by a narrowing of the meatus, which might cause sudden or often urges to urinate and burning during the process.
== Toxicity == Lectins are one of many toxic constituents of many raw plants that are inactivated by proper processing and preparation (e.g., cooking with heat, fermentation). For example, raw kidney beans naturally contain toxic levels of lectin (e.g. phytohaemagglutinin). Adverse effects may include nutritional deficiencies, and immune (allergic) reactions.
== See also == Gluconeogenesis – A process where glucose can be synthesized by non-carbohydrate sources. Glycobiology Glycogen Glycoinformatics Glycolipid Glycome Glycomics Glycosyl Macromolecule Saccharic acid
Bacterial infections may be treated with antibiotics, which are classified as bacteriocidal if they kill bacteria or bacteriostatic if they just prevent bacterial growth. There are many types of antibiotics and each class inhibits a process that is different in the pathogen from that found in the host. For example, the antibiotics chloramphenicol and tetracyclin inhibit the bacterial ribosome but not the structurally different eukaryotic ribosome, so they exhibit selective toxicity. Antibiotics are used both in treating human disease and in intensive farming to promote animal growth. Both uses may be contributing to the rapid development of antibiotic resistance in bacterial populations. Phage therapy, using bacteriophages can also be used to treat certain bacterial infections.
Sources: en.wikipedia.org
On 3 January 2026, the United States launched a military intervention in Venezuela and captured Venezuelan president Nicolás Maduro and his wife, Cilia Flores, leading to reactions from across the world. Several governments condemned the intervention, with some describing them as a violation of international law, while others expressed support, vague apprehension or were noncommittal. Most condemnations for the strikes came from countries in Africa, Asia, and most of Latin America, whereas most countries in Europe and North America, particularly NATO member states, supported the airstrikes on Venezuela and capture of Maduro.
American cockroaches generally live in moist areas but can survive in dry areas if they have access to water. They prefer high temperatures around 29 °C (84 °F) and do not tolerate low temperatures. These cockroaches are common in basements, crawl spaces, cracks and crevices of porches, foundations, and walkways adjacent to buildings. In residential areas outside the tropics, these cockroaches live in basements and sewers and may move outdoors into yards during warm weather. Adult American cockroaches were not able to survive several days at ≤10°C. Under constant temperatures of 8, 9, and 10°C, approximately 40% of cockroaches died within 72 hours.
== Theory == Atmosphere within the package can be modified passively or actively. In passive MAP, the high concentration of CO2 and low O2 levels in the package is achieved over time as a result of respiration of the product and gas transmission rates of the packaging film. This method is commonly used for fresh respiring fruits and vegetables. Reducing O2 and increasing CO2 slows down respiration rate, conserves stored energy, and therefore extended shelf life. On the other hand, active MA involves the use of active systems such as O2 and CO2 scavengers or emitters, moisture absorbers, ethylene scavengers, ethanol emitters and gas flushing in the packaging film or container to modify the atmosphere within the package. The mixture of gases selected for a MA package depends on the type of product, the packaging materials and the storage temperature. The atmosphere in an MA package consists mainly of adjusted amounts of N2, O2, and CO2. Reduction of O2 promotes delay in deteriorative reactions in foods such as lipid oxidation, browning reactions and growth of spoilage organisms. Low O2 levels of 3-5% are used to slow down respiration rate in fruits and vegetables. In the case of red meat, however, high levels of O2 (~80%) are used to reduce oxidation of myoglobin and maintain an attractive bright red color of the meat. Meat color enhancement is not required for pork, poultry and cooked meats; therefore, a higher concentration of CO2 is used to extend the shelf life. Levels higher than 10% of CO2 are phytotoxic for fruit and vegetables, so CO2 is maintained below this level.
== Use and effects == According to Alexander Shulgin in his book TiHKAL (Tryptamines I Have Known and Loved), DET's dose range is 50 to 100 mg orally and its duration is 2 to 4 hours. It was also assessed at oral doses of 44 to 400 mg, though 150 mg was described as "a little too much" and the 400 mg dose was simply described as "too high". Its onset is 40 minutes to more than 1 hour and peak effects occurred at just over 1 hour. In addition to oral administration, DET was assessed by smoking at doses of 40 to 90 mg, by subcutaneous injection at a dose of 40 mg, by intramuscular injection at a dose of 60 mg, and by intravenous injection at a dose of 60 mg. By these routes, it has a faster onset than when taken orally. The drug is said to taste terrible when smoked, like "burning plastic". DET was initially assumed to be inactive orally similarly to dimethyltryptamine (DMT), but this proved to be incorrect. The effects of DET have been reported to include similar "illusions" and hallucinations" as DMT, a wave-like time course of effects, closed-eye visuals, open-eye visuals, auditory and olfactory hallucinations, synesthesia, feeling like in another world, cosmic thinking, mystical and philosophical feelings, dream-like mysteriousness of objects, greater emotional significance of objects, peoples' faces seeming "mask-like", enhanced appreciation of art, architecture, and music, feeling like a small child perceiving the world and discovering it anew, time dilation, enjoyment and euphoria, increased empathy, and emotional insights.
C-reactive protein (CRP) is an annular (ring-shaped) pentameric protein found in blood plasma, whose circulating concentration rises in response to inflammation. It is an acute-phase protein of hepatic origin that increases following interleukin-6 secretion by macrophages and T cells. Its physiological role is to bind to lysophosphatidylcholine expressed on the surface of dead or dying cells (and some types of bacteria) in order to activate the complement system via C1q. CRP is synthesized by the liver in response to factors released by macrophages, T cells and fat cells (adipocytes). It is a member of the pentraxin family of proteins. It is not related to C-peptide (insulin) or protein C (blood coagulation). C-reactive protein was the first pattern recognition receptor (PRR) to be identified.
Sources: en.wikipedia.org
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.
Afamelanotide is the linear analogue [Nle4-D-Phe7]-alpha-MSH, sometimes called melanotan I, while melanotan II is cyclic and carries three further substitutions. The two are distinct molecules and are not interchangeable in analytical testing.
Binding to the four melanocortin receptor subtypes is well documented in vitro. The relative contribution of each subtype to whole-body effects in humans is far less certain.
It is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, containing seven amino acids with a lactam ring and a D-configured phenylalanine residue. It is supplied as a lyophilised powder for laboratory research.