A practical reference on alpha-MSH analogue: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
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.
Melanotan-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
Quality assessment of research-grade peptide rests mainly on reversed-phase high-performance liquid chromatography for purity and on mass spectrometry for identity confirmation. A single main peak above a stated threshold, commonly ninety-eight percent by peak area, is the usual release criterion applied by suppliers. Independent analyses commissioned by laboratories and consumer organisations have repeatedly reported discrepancies between label claims and measured content, including truncated sequences, residual trifluoroacetate, and lower-than-declared peptide mass. Those findings do not establish that every supplier is unreliable, but they indicate that purity figures printed on a vial are claims requiring verification rather than settled facts.
Regulatory treatment varies by jurisdiction and has changed over time. In several countries the peptide is handled as an unapproved prescription medicine, and import or sale for human use is restricted, while elsewhere it falls under poisons or controlled-substance schedules. Enforcement activity against online vendors has been reported in Australia, New Zealand, the United Kingdom and the United States. Scholarly writing discusses melanotan-2 chiefly as an experimental tool and as a case study in unregulated peptide supply, and its precise legal position in any given country should be checked against current national schedules.
Lyophilised melanotan-2 is comparatively robust when kept dry, cold and dark, and a desiccated powder stored at minus twenty degrees Celsius or below is generally expected to retain its chemical integrity for extended periods. In solution the peptide is far less stable, with degradation proceeding through oxidation of tryptophan and histidine residues, hydrolysis adjacent to the lactam bridge, and aggregation at higher concentrations. Repeated freeze-thaw cycling accelerates loss of the parent peak. Working aliquots are therefore prepared once, held cold, and used without letting the stock return to ambient temperature.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Alpha-MSH analogue with a lactam ring |
| Molecular formula | C50H69N15O9 | Commonly cited value for the neutral peptide |
| Molecular weight | 1024.18 g/mol | Calculated for the free molecule |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water, DMSO and ethanol | Dissolution in pure water is often slow |
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.
Regulatory status varies by jurisdiction, and the substance is frequently described as unapproved for therapeutic use. Some authorities classify it alongside prescription-only medicines or controlled categories, while others address it through general consumer protection rules. Analytical surveys have reported mismatches between label claims and measured content in products sold online, although the scope of such testing is limited. Whether these discrepancies are widespread remains an open question. Discussion in the literature therefore tends to combine chemistry, supply-chain observation and policy analysis.
The material is commonly handled as a lyophilized powder in sealed vials. The solid dissolves readily in water and in polar organic solvents, producing a clear solution after reconstitution. Light, heat and repeated freeze-thaw cycles are the concerns most often raised in handling guidance, because peptide bonds and the constrained ring can degrade. Working solutions are generally prepared fresh, and material left in solution is treated as less stable than the dry form. These properties shape how laboratories store and aliquot reference material.
=== Potential use of MRI/fMRI in diagnosis === In 2018, the American Psychological Association commissioned a review to reach a consensus on whether modern clinical MRI/fMRI will be able to be used in the diagnosis of mental health disorders. The criteria presented by the APA stated that the biomarkers used in diagnosis should:
=== Notable faculty === Emily Anderson - first professor of German Nicholas Canny - historian Colm McDonald - professor of psychiatry Michael D. Higgins - sociologist, 9th President of Ireland William King - geologist Alice Perry - engineer Gerard Quinn - jurist, specialist in international and comparative disability law and policy Niamh Reilly - sociologist and political scientist George Johnstone Stoney - physicist
Harris also expressed support for student debt relief, and said she supported raising the minimum wage. In response to the housing crisis in the United States, Harris said she would increase home construction to reduce housing costs, arguing that it negatively impacts the economy and hurts working-class families. Harris proposed directing $40 billion to construction companies to build starter homes, and promised to send $25,000 in down-payment assistance to every first time home buyer. Harris said she would urge Congress to enforce fair housing laws and pass a bill to bar property owners from using services that "coordinate" rents through the passage of the Preventing the Algorithmic Facilitation of Rental Housing Cartels Act, and also call on Congress to pass the Stop Predatory Investing Act by removing tax benefits to Wall Street firms that buy up large numbers of single-family homes. Trump proposed further individual and corporate tax cuts beyond the 2017 Tax Cuts and Jobs Act. Trump argued that keeping taxes low for the wealthy increases job creation, and that these policies coupled with a crackdown in illegal immigration and reduction in inflation would help the middle class. Trump said he would reduce regulation of business through the creation of an efficiency commission led by Musk, along with reducing environmental regulation. By October 2024, Musk was Trump's second-largest individual campaign donor.
Examples of landmark, and frequently controversial judgments, include Van Gend en Loos (holding EU law to created a new legal order, and citizens could sue for treaty rights), Mangold v Helm (establishing equality as a general principle of EU law), and Kadi v Commission (confirming international law had to conform with basic principles of EU law). Until 2016, there was the European Union Civil Service Tribunal, which dealt with EU institutions' staff issues.
Sources: en.wikipedia.org
=== Modulating fibrosis === Role of Thy-1 in fibrosis and fibroblast differentiation may have some tissue variation. Thy1 knock out mice have increased fibrosis in the lung. Fibrosis induced by chemotherapeutic agent Bleomycin is also increased in these mice.
=== Oxides === Neptunium has two stable oxides, which are NpO2 and Np2O5. Np3O8 was reported in earlier literatures, though some studies suggesting that claims of Np3O8 are actually the result of mistaken analysis of Np2O5. The existence of another oxide Np4O9 has been suggested, but it has not been fully characterized. Although neptunium oxides have not been produced with neptunium in oxidation states as high as those possible with the adjacent actinide uranium, neptunium oxides are more stable at lower oxidation states. This behavior is illustrated by the fact that NpO2 can be produced by simply burning neptunium salts of oxyacids in air. The greenish-brown NpO2 is very stable over a large range of pressures and temperatures and does not undergo phase transitions at low temperatures. It does show a phase transition from face-centered cubic to orthorhombic at around 33–37 GPa, although it returns to its original phase when pressure is released. It remains stable under oxygen pressures up to 2.84 MPa and temperatures up to 400 °C. Np2O5 is black-brown in color and monoclinic with a lattice size of 418×658×409 picometres. It is relatively unstable and decomposes to NpO2 and O2 at 420–695 °C. Although Np2O5 was initially subject to several studies that claimed to produce it with mutually contradictory methods, it was eventually prepared successfully by heating neptunium peroxide to 300–350 °C for 2–3 hours or by heating it under a layer of water in an ampoule at 180 °C.
=== PPAR-delta agonists === PPARδ (delta) is the main target of a research chemical named GW501516. It has been shown that agonism of PPARδ changes the body's fuel preference from glucose to lipids. In August 2024, seladelpar became the first PPARδ agonist to be approved for clinical use.
Aging dogs require specialized catering. Commercially available senior dog diets address their physiological changes through various ingredients and nutrients. When looking for a senior dog food, one of the first things that should be taken into consideration is the energy content of the diet. The maintenance energy requirements decrease as a dog ages due to the loss in lean body mass that occurs. Therefore, senior dogs will require a diet with a lowered energy content compared to non senior diets. Although senior dogs require lower energy content diets, they will also require diets that are higher in protein and protein digestibility. This is due to the fact that dogs have a reduced ability to synthesize proteins as they age. Joint and bone health is an important factor to be considered when purchasing a senior dog food. The addition of glucosamine and chondroitin sulfate has been shown to improve cartilage formation, the composition of synovial fluid, as well as improve signs of osteoarthritis. The calcium to phosphorus ratio of senior dog foods is also important. Calcium and phosphorus are considered essential nutrients, according to AAFCO. Gastrointestinal health is another important factor to consider in the aging dog. Sources of fiber such as beet pulp and flaxseed should be included within senior dog foods to help improve stool quality and prevent constipation. A current technology that is being used to improve gastrointestinal health of aging dogs is the addition of fructooligosaccharides and mannanoligosaccharides.
The LE cell was discovered in bone marrow in 1948 by Hargraves et al. In 1957 Holborow et al. first demonstrated ANA using indirect immunofluorescence. This was the first indication that processes affecting the cell nucleus were responsible for SLE. In 1959 it was discovered that serum from individuals with SLE contained antibodies that precipitated with saline extracts of nuclei, known as extractable nuclear antigens (ENAs). This led to the characterisation of ENA antigens and their respective antibodies. Thus, anti-Sm and anti-RNP antibodies were discovered in 1966 and 1971, respectively. In the 1970s, the anti-Ro/anti-SS-A and anti-La/anti-SS-B antibodies were discovered. The Scl-70 antibody was known to be a specific antibody to scleroderma in 1979, however the antigen (topoisomerase-I) was not characterised until 1986. The Jo-1 antigen and antibody were characterised in 1980.
Sources: en.wikipedia.org
== Notable cases == Ab-Soul, American hip-hop recording artist and member of Black Hippy Padma Lakshmi, actress, model, television personality, and cookbook writer Manute Bol, former NBA player. Bol died from complications of Stevens–Johnson syndrome as well as kidney failure. Gene Sauers, three-time PGA Tour winner Samantha Reckis, a seven-year-old Plymouth, Massachusetts girl who lost the skin covering 95% of her body after taking children's Motrin in 2003. She survived, and in 2013, a jury awarded her $63M in a lawsuit against Johnson & Johnson, one of the largest lawsuits of its kind. The decision was upheld in 2015. Karen Elaine Morton, a model and actress who appeared in Tommy Tutone's "867-5309/Jenny" video and was Playmate of the Month in the July 1978 issue of Playboy Magazine.
An agonist is a chemical capable of binding to a receptor, such as a neurotransmitter receptor, and initiating the same reaction typically produced by the binding of the endogenous substance. An agonist of a neurotransmitter will thus initiate the same receptor response as the transmitter. In neurons, an agonist drug may activate neurotransmitter receptors either directly or indirectly. Direct-binding agonists can be further characterized as full agonists, partial agonists, inverse agonists. Direct agonists act similar to a neurotransmitter by binding directly to its associated receptor site(s), which may be located on the presynaptic neuron or postsynaptic neuron, or both. Typically, neurotransmitter receptors are located on the postsynaptic neuron, while neurotransmitter autoreceptors are located on the presynaptic neuron, as is the case for monoamine neurotransmitters; in some cases, a neurotransmitter utilizes retrograde neurotransmission, a type of feedback signaling in neurons where the neurotransmitter is released postsynaptically and binds to target receptors located on the presynaptic neuron. Nicotine, a compound found in tobacco, is a direct agonist of most nicotinic acetylcholine receptors, mainly located in cholinergic neurons. Opiates, such as morphine, heroin, hydrocodone, oxycodone, codeine, and methadone, are μ-opioid receptor agonists; this action mediates their euphoriant and pain relieving properties.
==== By phosphate ==== In cyanobacteria, inorganic phosphate (Pi) also participates in the co-ordinated regulation of photosynthesis: Pi binds to the RuBisCO active site and to another site on the large chain where it can influence transitions between activated and less active conformations of the enzyme. In this way, activation of bacterial RuBisCO might be particularly sensitive to Pi levels, which might cause it to act in a similar way to how RuBisCO activase functions in higher plants.
== Adverse effects == As a diuretic, ethacrynic acid can cause frequent urination, but this usually resolves after taking the drug for a few weeks. Ethacrynic acid can also cause low potassium levels, which may manifest as muscle cramps or weakness. It has also been known to cause reversible or permanent hearing loss (ototoxicity) and liver damage when administered in extremely high dosages. On oral administration, it produces diarrhea; intestinal bleeding may occur at higher doses.
== Etymology == The singular alga is the Latin word for "seaweed" and retains that meaning in English. The etymology is obscure. Although some speculate that it is related to Latin algēre, "be cold", no reason is known to associate seaweed with temperature. A more likely source is alliga, "binding, entwining". The Ancient Greek word for "seaweed" was φῦκος (phŷkos), which could mean either the seaweed (probably red algae) or a red dye derived from it. The Latinization, fūcus, meant primarily the cosmetic rouge. The etymology is uncertain, but a strong candidate has long been some word related to the Biblical פוך (pūk), "paint" (if not that word itself), a cosmetic eye-shadow used by the Ancient Egyptians and other inhabitants of the eastern Mediterranean. It could be any color: black, red, green, or blue. The study of algae is most commonly called phycology (from Greek phykos 'seaweed'); the term algology is falling out of use.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.
No national medicines agency has approved melanotan-2 for clinical use. Afamelanotide, a related but distinct peptide, holds a marketing authorisation in the European Union for a rare photosensitivity disorder. Melanotan-2 itself is handled as a laboratory chemical.
Its broad activity across melanocortin receptors makes it a tool for probing pigmentation, appetite and vascular signalling. Early trials recorded skin darkening and other effects that were not the original focus of the work. Those observations generated hypotheses that later studies have examined.
Solutions are best kept cold, protected from light, and buffered to a pH that limits hydrolysis. Dividing a stock into single-use aliquots avoids repeated freeze-thaw cycles, which measurably reduce the intact parent peak over time.