A practical reference on melanotan-2: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-03-25. Anything still debated is marked as such rather than presented as settled.
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.
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.
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 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.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Melanotan II; MT-II; N-acetyl-norleucyl-cyclo[Asp-His-D-Phe-Arg-Trp-Lys] amide | Naming follows peptide convention; the numeral distinguishes it from melanotan-1 |
| Molecular formula | C50H69N15O9 | Includes the lactam bridge; no counter-ion assumed |
| Monoisotopic mass | 1023.53 Da | Free base; salts and counter-ions shift the observed value |
| Appearance | White to off-white lyophilised powder | Batch-to-batch colour variation is not itself proof of impurity |
| Typical analytical method | RP-HPLC purity determination with ESI-MS identity confirmation | Retention time alone does not establish sequence identity |
Melanocytes are the pigment-producing cells of the skin, and they carry melanocortin-1 receptors on their surface. When the receptor is activated, cyclic adenosine monophosphate rises inside the cell and raises the activity of enzymes such as tyrosinase, which increases melanin output. Melanotan-2 binds melanocortin-1 receptors in vitro and in animal models, and this binding is generally described as the basis for the tanning effect. Other receptors account for different effects: melanocortin-4 receptors contribute to appetite and erectile signalling, while melanocortin-3 and melanocortin-5 receptors contribute to energy balance and exocrine function.
Early published reports described melanotan-2 as a tanning agent without sun protection, which means darkening is not the same as protection against ultraviolet radiation. Later studies explored the peptide in erectile dysfunction, hemorrhagic shock, and some skin conditions. No regulator in the United States or Europe has approved it for clinical use. Many products labelled melanotan-2 are sold without approval and their identity and purity are unverified. Its long-term safety in humans remains an open question.
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.
Radical transfer with a Cobalamin B12 cofactor and SAM has been shown with the few characterized radical SAM methyltransferases. Although the evidence points to radical β-methylation during bottromycin biosynthesis, it remains to be seen whether bioinformatic hypothesis and feeding studies will be supported by in vitro activity assays. The Val3Ala substitution in bottromycin D does not change the β-methylation pattern between bottromycin A2 and D because Val3 is the only valine not methylated in bottromycin A2. As such, there are still three predicted radical SAM dependent enzymes in the bottromycin D biosynthetic cluster: bstC, bstF, and bstJ. As of 2013, all published biosynthetic studies have been bioinformatic or cell-based. No biochemical assays directly demonstrating protein function have yet been published. It is likely that in vitro mechanistic studies to better elucidate the biosynthetic pathway will be forthcoming.
=== Conformational states === Simulations identified three distinct active-state conformational states of KOR: the canonical active state, an alternative state, and an occluded state. The alternative state, characterized by specific transmembrane domain conformations, correlates with β-arrestin2-biased signaling. The occluded state, in which the intracellular portion of transmembrane helix 7 rotates clockwise toward transmembrane helix 2, appears to favor G protein coupling whilst disfavoring β-arrestin recruitment. Specific residues within the receptor binding pocket differentially influence G protein versus β-arrestin signaling. Disruption of the ionic interaction by certain agonists increases the distance between the extracellular ends of transmembrane helices 5 and 6, contributing to ligand-specific transducer coupling preferences.
Pizotifen is a serotonin antagonist acting mainly at the 5-HT2A, 5-HT2B, and 5-HT2C receptors. It also has some activity as an antihistamine as well as some anticholinergic activity. The drug binds non-selectively to many targets, including serotonin, dopamine, adrenergic, histamine, and muscarinic acetylcholine receptors. Besides its serotonin 5-HT2 receptor antagonism, pizotifen is a low-potency moderate-efficacy partial agonist of the serotonin 5-HT1A receptor. Pizotifen is able to dose-dependently and fully antagonize the discriminative stimulus effects of the serotonin–norepinephrine–dopamine releasing agent and serotonin 5-HT2 receptor agonist MDMA in rodent drug discrimination tests. Conversely, the related drug cyproheptadine was only partially effective and clozapine was ineffective. All three of these agents, pizotifen, cyproheptadine, and clozapine act as non-selective monoamine receptor antagonists. Pizotifen also fully blocks the effects of serotonergic psychedelics, including LSD, mescaline, 5-MeO-DMT, and DOM, in drug discrimination tests. The antimigraine activity of pizotifen might be specifically due to serotonin 5-HT2B receptor blockade.
In addition to Denmark proper, the Kingdom of Denmark comprises two autonomous constituent countries in the North Atlantic Ocean: Greenland and the Faroe Islands. Both use the Danish krone as their currency, but form separate economies, having separate national accounts etc. Both countries receive an annual fiscal subsidy from Denmark which amounts to about 25% of Greenland's GDP and 11% of Faroese GDP. For both countries, the fishing industry is a major economic activity. Neither Greenland nor the Faroe Islands are members of the European Union. Greenland left the European Economic Community in 1986, and the Faroe Islands declined membership in 1973, when Denmark joined.
=== Dental === Silanization is often used to treat ceramics used for dental restorations and repairs. Applying silane coupling agents after grit blasting the ceramic material has been shown to produce durable resin bonding. Additionally, for titanium and other metal implant features in wires and crowns, application of silane coupling agents followed by resin composite cement has produced durable bonding in a clinical application. While silane coupling agents are widely used in dental practices, they are subject to bond degradation due to the environment of the oral cavity, weakening the adhesion between the surfaces that they are used to connect.
Sources: en.wikipedia.org
== Plant hormone signaling == The plant hormone auxin binds Tir1 (Transport Inhibitor Response 1). Tir1 is an Auxin Signaling F-box Protein (AFB) that acts as an auxin receptor. Auxin-bound Tir1 stimulates binding of SCF-Tir1 to the AUX/IAA repressor. Subsequent degradation of the repressor results in activation of AUX/IAA (i.e. auxin-responsive) genes. The plant hormone Jasmonate binds Coi1, an FBP. SCF-Coi1 then binds the JAZ transcription factor and targets it for degradation. Degradation of the JAZ transcription factor allows for the transcription of the jasmonate responsive genes.
The sequence in which the subshells are filled is given in most cases by the Aufbau principle, also known as the Madelung or Klechkovsky rule (after Erwin Madelung and Vsevolod Klechkovsky respectively). This rule was first observed empirically by Madelung, and Klechkovsky and later authors gave it theoretical justification. The shells overlap in energies, and the Madelung rule specifies the sequence of filling according to:
Skittles are produced in a wide variety of flavors and colors, including sour varieties. Skittles has hinted at new flavor releases on its Facebook page, using such statuses as "Locking myself in the Rainbow kitchen until I see some results!" A 2011 posting contained confirmation of a new flavor: "Putting the last touches on a new Skittles flavor. Tweak the Rainbow." In the United States and Canada, in 2013, Skittles replaced the lime-flavored Skittles with green apple, causing a backlash from many consumers. The lime flavor became part of the Darkside packets, which were discontinued in 2015 and followed up by the Orchards packets, which were discontinued in 2017. Lime was also part of the "Long Lost Lime" packets that came out in summer 2017 and 2018. The Darkside flavor was revived in 2019. In 2021, the "All Lime" packets containing only the lime flavor were released for a limited time. In September 2021, Skittles announced that the green apple-flavored Skittles would be replaced with the original lime flavor. In 2022, Skittles Gummies were released. In October 2024, Skittles released their own version of freeze-dried Skittles called Skittles POP'd. It comes in the Original and Sour Skittles flavors.
==== Integration of Chinese and Western medicine (1368–1949) ==== During the Ming (1368–1644) and Qing (1644–1912) dynasties, medical discoveries slowed but practitioners achieved significant knowledge integration across cultures. Over one hundred comprehensive medical monographs were cultivated, many synthesizing developments in the study of wasting-thirst and of diabetes. Zhang Xichun (1860–1933), a renowned integrator of medical knowledge, produced (among other works) Yīxué zhōng zhōng cānxī lù (医学衷中参西录; "The Integration of Traditional Chinese and Western Medicine"). In a dedicated chapter named "Xiāo-kě therapies", he discussed the following aspects synthesizing wasting-thirst and diabetes: nomenclature, theories (pathologies), primary formulae, medications (herbology and pharmacology), nursing (diet and maintenance), medical cases, and integrated analysis (protein and essence; qi and fluids). Yu Yunxiu (1879–1954), a Japanese-educated practitioner of Western medicine aligned with the modernizer camp of the Chinese Ministry of Health, attempted to forbid the practice of Chinese medicine in 1929. In 1939, he wrote on the rough equivalence of wasting-thirst and diabetes.
Sources: en.wikipedia.org
The ÄKTA explorer was the first high end FPLC (Fast Protein Liquid Chromatography) system that was developed for Life Science research by the Swedish company Pharmacia in 1994. Its purpose was to simplify and automatize protein purification. It was followed by a line of similar devices (the "Äkta" line). The product line name was transferred together with the sale of Pharmacia first to Amersham and then to GE Healthcare. Although protein purification is possible with a large range of chromatographic devices, the Äkta line represents together with BioRad's NGC line the only devices that were specifically designed for this purpose both from the hardware and software perspective. Main users of these devices are the pharmaceutical industry and academic researchers.
== Taxonomy == The classification of corals has been discussed for millennia, owing to having similarities to both plants and animals. Aristotle's pupil Theophrastus described the red coral, korallion, in his book on stones, implying it was a mineral, but he described it as a deep-sea plant in his Enquiries on Plants, where he also mentions large stony plants that reveal bright flowers when under water in the Gulf of Heroes. Pliny the Elder stated boldly that several sea creatures including sea nettles and sponges "are neither animals nor plants, but are possessed of a third nature (tertia natura)". Petrus Gyllius copied Pliny, introducing the term zoophyta for this third group in his 1535 book On the French and Latin Names of the Fishes of the Marseilles Region; it is popularly but wrongly supposed that Aristotle created the term. Gyllius further noted, following Aristotle, how hard it was to define what was a plant and what was an animal. The Babylonian Talmud refers to coral among a list of types of trees, and the 11th-century French commentator Rashi describes it as "a type of tree (מין עץ) that grows underwater that goes by the (French) name 'coral'." The Persian polymath Al-Biruni (d.1048) classified sponges and corals as animals, arguing that they respond to touch. Nevertheless, people believed corals to be plants until the eighteenth century when William Herschel used a microscope to establish that coral had the characteristic thin cell membranes of an animal.
== Notable people == Jacob M. Gile (1849–1937), architect in Colorado, born in Lebanon Doug Jones, MLB All-Star relief pitcher Mel Kenyon, Hall of Fame midget car driver; had four top-five finishes in Indianapolis 500 Sylvia Likens, murder victim, born in Lebanon, murdered in Indianapolis in 1965 when she was 16 Ray Long, editor of Cosmopolitan from 1919 to 1931, born in Lebanon Ami McKay, novelist, playwright and journalist Rick Mount, 1966 Indiana "Mr. Basketball" award recipient, 3x All-American Purdue player William Perigo, basketball head coach at Western Michigan University and University of Michigan Drew Powell, actor, is best known for his role as Hoss Cartwright on the TV series Ponderosa Allen Saunders, cartoonist and writer, Mary Worth G. Thomas Tanselle, textual critic, bibliographer, and book collector, especially known for his work on Herman Melville Craig Terrill, former Purdue and Seattle Seahawks football player Herman B Wells, former President of Indiana University, attended Lebanon High School
=== Pleural space pressure === A pneumothorax (collapsed lung) is an abnormal collection of air in the pleural space that causes an uncoupling of the lung from the chest wall. The lung cannot expand against the air pressure inside the pleural space. An easy to understand example is a traumatic pneumothorax, where air enters the pleural space from outside the body, as occurs with puncture to the chest wall. Similarly, scuba divers ascending while holding their breath with their lungs fully inflated can cause air sacs (alveoli) to burst and leak high pressure air into the pleural space.
== Applications == Microfluidic structures include micropneumatic systems, i.e. microsystems for the handling of off-chip fluids (liquid pumps, gas valves, etc.), and microfluidic structures for the on-chip handling of nanoliter (nl) and picoliter (pl) volumes. To date, the most successful commercial application of microfluidics is the inkjet printhead. Additionally, microfluidic manufacturing advances mean that makers can produce the devices in low-cost plastics such as polymethymethacrylate (PMMA), polystyrene, cyclic olefin polymer (COP) and polyvinyl chloride (PVC) and automatically verify part quality. Microfluidic devices are often first produced using fabrication methods such as soft lithography, micro milling or laser machining to validate microchannel designs before transitioning to scalable thermoplastic manufacturing processes such as injection molding. Advances in microfluidics technology promise to improve molecular biology procedures for enzymatic analysis (e.g., glucose and lactate assays), DNA analysis (e.g., polymerase chain reaction and high-throughput sequencing), proteomics, and in chemical synthesis. Microfluidic biochips integrate assay operations such as detection, with sample pre-treatment and sample preparation. A promising application area for biochips is clinical pathology, especially the point-of-care diagnosis of diseases.
Sources: en.wikipedia.org
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.
The natural hormone is a linear tridecapeptide that is rapidly degraded in circulation. Melanotan-2 is shortened, cyclised, N-terminally acetylated, and carries a D-amino acid substitution, all of which slow enzymatic breakdown.
No national medicines regulator has approved melanotan-2 for therapeutic or cosmetic use. In several jurisdictions it is treated as an unapproved prescription medicine, and its legal classification differs from country to country.
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.