Everything below concerns alpha-MSH. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-11-15. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Melanocortin receptor agonist |
| Molecular formula | C50H69N15O9 | Neutral form, mass near 1024.2 g/mol |
| Primary targets | MC1R, MC3R, MC4R, MC5R | Binding is non-selective across subtypes |
| Related compounds | Alpha-MSH, melanotan I, afamelanotide | Structurally or functionally related peptides |
| Common abbreviations | MT-II, MT-2 | Naming in the literature is not uniform |
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.
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.
The compound was developed in the late 1980s and 1990s by academic researchers investigating photoprotection. The rationale held that stimulating melanin production might reduce ultraviolet damage to skin and lower skin cancer risk. Early work examined receptor binding, pigment response, and short-term tolerability in small studies. That program did not produce an approved drug, and formal development stalled after early-phase trials. Whether induced pigmentation confers meaningful photoprotection remains an open question.
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.
=== Assessment === Although CoQ10 may be measured in blood plasma, these measurements reflect dietary intake rather than tissue status. Currently, most clinical centers measure CoQ10 levels in cultured skin fibroblasts, muscle biopsies, and blood mononuclear cells. Culture fibroblasts can be used also to evaluate the rate of endogenous CoQ10 biosynthesis, by measuring the uptake of 14C-labeled p-hydroxybenzoate. CoQ10 is studied as an adjunctive therapy to reduce inflammation in periodontitis.
According to the gene centered view of evolution, most genes are "selfish" only insofar as to compete with other genes or alleles but usually they fulfill a function for the organisms, whereas "parasitic genetic elements", at least initially, do not make a positive contribution to the fitness of the organism. As of December 2019, the UniProtKB database contains 188 entries manually annotated as inteins, ranging from just tens of amino acid residues to thousands. The first intein was found encoded within the VMA gene of Saccharomyces cerevisiae. They were later found in fungi (ascomycetes, basidiomycetes, zygomycetes and chytrids) and in diverse proteins as well. A protein distantly related to known inteins containing protein, but closely related to metazoan hedgehog proteins, has been described to have the intein sequence from Glomeromycota. Many of the newly described inteins contain homing endonucleases and some of these are apparently active. The abundance of intein in fungi indicates lateral transfer of intein-containing genes. While in eubacteria and archaea, there are 289 and 182 currently known inteins. Not surprisingly, most intein in eubacteria and archaea are found to be inserted into nucleic acid metabolic protein, like fungi. Inteins vary greatly, but many of the same intein-containing proteins are found in a number of species. For example, pre-mRNA processing factor 8 (Prp8) protein, instrumental in the spliceosome, has seven different intein insertion sites across eukaryotic species.
As gold nanoparticles (AuNPs) are further investigated for targeted drug delivery in humans, their toxicity needs to be considered. For the most part, it is suggested that AuNPs are biocompatible, but the concentrations at which they become toxic needs to be determined, and if those concentrations fall within the range of used concentrations. Toxicity can be tested in vitro and in vivo. In vitro toxicity results can vary depending on the type of the cellular growth media with different protein compositions, the method used to determine cellular toxicity (cell health, cell stress, how many cells are taken into a cell), and the capping ligands in solution. In vivo assessments can determine the general health of an organism (abnormal behavior, weight loss, average life span) as well as tissue specific toxicology (kidney, liver, blood) and inflammation and oxidative responses. In vitro experiments are more popular than in vivo experiments because in vitro experiments are more simplistic to perform than in vivo experiments.
Sources: en.wikipedia.org
== Properties == Industrially produced guanidinoacetic acid is sold as a white (to yellowish) fine powder, which is granulated for improve handling, metering and uptake with starch into aggregates with a mean diameter of 200-400 microns. The granulate provides a long-term stability of glycocyamine. The shelf Life of guanidinoacetate in acidic aqueous solution is significantly higher than that of creatine, which cyclizes to creatinine under acid catalysis.
This principle of self-determination had been declared on numerous occasions subsequent to the declaration – President Wilson's January 1918 Fourteen Points, Sykes's Declaration to the Seven in June 1918, the November 1918 Anglo-French Declaration, and the June 1919 Covenant of the League of Nations that had established the mandate system. In an August 1919 memo Balfour acknowledged the inconsistency among these statements, and further explained that the British had no intention of consulting the existing population of Palestine. The results of the ongoing American King–Crane Commission of Enquiry consultation of the local population – from which the British had withdrawn – were suppressed for three years until the report was leaked in 1922. Subsequent British governments have acknowledged this deficiency, in particular the 1939 committee led by the Lord Chancellor, Frederic Maugham, which concluded that the government had not been "free to dispose of Palestine without regard for the wishes and interests of the inhabitants of Palestine", and the April 2017 statement by British Foreign Office minister of state Baroness Anelay that the government acknowledged that "the Declaration should have called for the protection of political rights of the non-Jewish communities in Palestine, particularly their right to self-determination."
=== Ribozyme and deoxyribozyme === Since discovery of ribozymes by Thomas Cech and Sidney Altman in the early 1980s, ribozymes have been shown to be a distinct class of metalloenzymes. Many ribozymes require metal ions in their active sites for chemical catalysis; hence they are called metalloenzymes. Additionally, metal ions are essential for structural stabilization of ribozymes. Group I intron is the most studied ribozyme which has three metals participating in catalysis. Other known ribozymes include group II intron, RNase P, and several small viral ribozymes (such as hammerhead, hairpin, HDV, and VS) and the large subunit of ribosomes. Several classes of ribozymes have been described. Deoxyribozymes, also called DNAzymes or catalytic DNA, are artificial DNA-based catalysts that were first produced in 1994. Almost all DNAzymes require metal ions. Although ribozymes mostly catalyze cleavage of RNA substrates, a variety of reactions can be catalyzed by DNAzymes including RNA/DNA cleavage, RNA/DNA ligation, amino acid phosphorylation and dephosphorylation, and carbon–carbon bond formation. Yet, DNAzymes that catalyze RNA cleavage reaction are the most extensively explored ones. 10-23 DNAzyme, discovered in 1997, is one of the most studied catalytic DNAs with clinical applications as a therapeutic agent. Several metal-specific DNAzymes have been reported including the GR-5 DNAzyme (lead-specific), the CA1-3 DNAzymes (copper-specific), the 39E DNAzyme (uranyl-specific) and the NaA43 DNAzyme (sodium-specific).
Sources: en.wikipedia.org
USAF Pararescue combat medics in Afghanistan used fentanyl lozenges in the form of lollipops on combat casualties from IED blasts and other trauma. The stick is taped to a finger and the lozenge put in the cheek of the person. When enough fentanyl has been absorbed, the (sedated) person generally lets the lollipop fall from the mouth, indicating sufficient analgesia and somewhat reducing the likelihood of overdose and associated risks.
According to the 2015–2016 Association of Research Libraries' "Spending by University Research Libraries" report, UA libraries are ranked as the 37th overall university library in North America (out of 114) for university investment. As of 2012, the UA's library system contains over six million print volumes, 1.1 million electronic books, and 74,000 electronic journals. The Main Library, opened in 1976, serves as the library system's reference, periodical, and administrative center; most of the main collections are housed here. The Main Library is on the southeast quadrant of campus near McKale Center and Arizona Stadium. In 2002, the Integrated Learning Center (ILC) was completed as a $20 million, 100,000-square-foot (10,000 m2) computer facility intended for use by incoming students. The ILC features classrooms, auditoriums, a courtyard with vending machines, and an expanded computer lab with several dozen workstations and 3D printing. Computers and 3D printing are available for use by the general public (with some restrictions) as well as by UA students, faculty and staff. The Arizona Health Sciences Library, built in 1996, is on the Health Sciences Center on the north end of campus and on the Phoenix Biomedical Campus, in the Health Sciences Education Building (HSEB). The library serves the Colleges of Medicine, Nursing, Pharmacy, Public Health, and Veterinary Medicine, the University of Arizona Health Network, and is a resource for health professionals and citizens across the state. An important part of the Main Library is the Special Collections library.
=== By technology === There are a large number of different time temperature indicators available in the market, based on different technologies. To the degree that these physical changes in the indicator match the degradation rate of the food, the indicator can help indicate probable food degradation. A few rules govern the design of TTI technology: the color-change needs to be irreversible and the relationship between rate-of-change and the temperature should match the application.
After independence in 1947, India shifted from the colonial economic model to a focus on industrialisation and poverty reduction. This transition brought a large expansion of government authority. Government spending as a share of gross domestic product (GDP) increased from 3 to 5 per cent in 1931 to 22 per cent by 1981. Public administration and state-owned enterprises became major employers. To manage this market intervention, India developed—during the 1950s—a comprehensive, federally managed statistical system to conduct large-scale sample surveys for monitoring and assessing living standards or effects of interventions. The Indian state utilised fiscal policy and international assistance to fund capital-intensive industrialisation and subsidise basic goods such as food, fertilisers, and electric power. However, by the 1970s, this heavy public spending became unsustainable. Domestic economic growth slowed, leading to a balance-of-payments crisis, whereas government spending flattened around 28–30 per cent of GDP. Government-led planning yielded mixed results. Many of India’s big economic changes were not planned by government bureaucrats. Thus, the 1970s Green Revolution, mass labour migration to the Middle East, and a garment-industry boom all emerged from global market forces and non-state actors; the government simply adapted to them after they were underway. A major shift occurred during the 1990s as India rejoined the global economy. The Indian government reduced import tariffs and enacted pro-market reforms.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide and a non-selective melanocortin receptor agonist. Structurally it is modelled on alpha-melanocyte-stimulating hormone, a peptide that occurs naturally in the body.
Activation of MC1R increases pigment synthesis independently of ultraviolet exposure, which is the mechanism usually cited for darkening without sun exposure. Ultraviolet light still influences skin response through separate biological pathways.
Because the peptide binds several melanocortin receptor subtypes, its effects are not confined to pigmentation. This complicates interpretation of both intended and unintended outcomes reported in studies.
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.