Everything below concerns MC1R. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry. Retention time supports identity, while the mass spectrum confirms the molecular weight of the intact peptide. Purity is frequently reported as a percentage of total peak area, a figure that depends on the wavelength, column and gradient used. Impurity profiling may also look for truncated sequences, oxidised forms and residual counterions. Amino acid analysis and peptide mapping provide orthogonal confirmation when required.
| 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 |
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.
Regulatory treatment varies by country. In the United States the peptide is not approved as a medicine, and products offered for human use may be treated as unapproved new drugs; some states also restrict sale. Australia, the United Kingdom, and European Union member states apply comparable restrictions to unapproved peptide products. Border agencies have seized shipments labelled as research chemicals. Classification may change over time, and the legal position for personal importation is not clearly settled in most published guidance.
Lyophilised melanotan-2 is supplied as a solid, which is more stable than a solution. The material is hygroscopic, so weighing is done quickly, in low humidity, with the container kept sealed. Reconstitution usually uses water for injection or bacteriostatic water, added down the wall of the vial to limit foaming. A reconstituted solution is held at 2 to 8 °C and kept away from light. Repeated freezing and thawing of the same vial is avoided because ice crystal formation and concentration effects degrade the peptide.
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.
== History == The individual subunits of the G protein complex were first identified in 1980 when the regulatory component of adenylate cyclase was successfully purified, yielding three polypeptides of different molecular weights. Initially, it was thought that Gα, the largest subunit, was the major effector regulatory subunit, and that Gβγ was largely responsible for inactivating the Gα subunit and enhancing membrane binding. However, downstream signalling effects of Gβγ were later discovered when the purified Gβγ complex was found to activate a cardiac muscarinic K+ channel. Shortly after, the Gβγ complex associated with a mating factor receptor-coupled G protein in yeast was found to initiate a pheromone response. Although these hypotheses were initially controversial, Gβγ has since been shown to directly regulate as many different protein targets as the Gα subunit. Recently, possible roles of the Gβγ complex in retinal rod photoreceptors have been investigated, with some evidence for the maintenance of Gα inactivation. However, these conclusions were drawn from in vitro experiments under unphysiological conditions, and the physiological role of the Gβγ complex in vision is still unclear. Nevertheless, recent in vivo findings demonstrate the necessity of the transducin Gβγ complex in the functioning of rod photoreceptors under low light conditions.
covalent bond Also molecular bond. A bond that involves the sharing of electron pairs between atoms. The stable balance of attractive and repulsive forces that occurs between atoms when they share electrons is known as covalent bonding.
For services to the community in Ross-on-Wye, Herefordshire. Sylvia Joan West. For services to the community in County Down. The Venerable Thomas Roderic West. Minister, Church of Ireland. For services to the community in County Down. David Wheeler. Chair, Lisnaskea Rovers Football Club. For services to Association Football in County Fermanagh. Martin John White. For services to Music in Northern Ireland. Dorothy Margaret Whittington. Volunteer, Oxford University Newcomers. For services to Volunteering and Higher Education. Gwendoline Ann Wickham. President, Guild of the Royal Hospital of St Bartholomew. For services to Charity and to the community in London. Dr Jane Wilcock. Chair, North West Faculty, Royal College of General Practitioners and lately General Practitioner, Silverdale Medical Practice, Swinton, Greater Manchester. For services to General Practice. Martin Peter Wild. For services to the community in Tamworth, Staffordshire. Jonathan Peter Willcocks. Musical Director, The Chichester Singers. For services to Music. Matthew James Willer. Founder, The Papillon Project. For services to Young People. Goodeson Lloyd Williams. For services to the community in the London Borough of Enfield during Covid-19. Howard Mansell Williams. For services to the Royal British Legion and to the community in Spondon, Derbyshire. Joan Barbara Williams. Diary Manager, Minister of State for Industry and Economic Security, Department for Business and Trade. For Public Service. Linda Elaine Williams. Volunteer Support Administrator, Welsh Ambulance Services NHS Trust.
having an acceptable treatment protocol in place that changes the outcome for patients diagnosed early with the disease an understanding of the condition's natural history an understanding about who will be treated as a patient a screening test that is reliable for both affected and unaffected patients and is acceptable to the public As diagnostic techniques have progressed, debates have arisen as to how screening programs should adapt. Tandem mass spectrometry has greatly expanded the potential number of diseases that can be detected, even without satisfying all of the other criteria used for making screening decisions. Duchenne muscular dystrophy is a disease that has been added to screening programs in several jurisdictions around the world, despite the lack of evidence as to whether early detection improves the clinical outcome for a patient.
== History == The Tetra Brik package was introduced in 1963, after a long process of development and built on the previous Tetra Classic tetrahedron package that laid the foundation for Tetra Pak. Despite the revolutionary character of the new retail system, by the end of the 1950s Ruben Rausing and the Tetra Pak management team realised that the Tetra Pak package portfolio needed to be supplemented by an additional rectangular model to continue to be competitive. Large amounts were spent on development, and in 1963 the first Tetra Brik packaging machine was installed in Motala in central Sweden. Due to its effective use of space and materials and the increased efficiency in distribution and storage that resulted from the rectangular shape, the Tetra Brik soon became Tetra Pak's best seller in Sweden and internationally and paved the way for Tetra Pak's enormous success during the 1970s and onwards. The Tetra Brik package family has since been extended and is currently composed of Tetra Brik and Tetra Brik Aseptic in the shapes Base, Square and Edge, ranging from volumes of 80 to 2000 ml and with a number of different caps. Tetra Brik has been distinguished as one of the 20th century's design icons. It featured in the 2004 Museum of Modern Art New York exhibition Humble Masterpieces and in the 2011 London Science Museum/Vitra Design Museum exhibition Hidden Heroes – The Genius of Everyday Things. It is now part of the permanent collection at the MoMA in New York.
Sources: en.wikipedia.org
=== Controlling pore size === The microstructural wavelength (average pore + wall thickness) can be described as a function of the solidification velocity v (λ= Av−n) where A is dependent on solids loading. There are two ways then that the pore size can be controlled. The first is to change the solidification speed that then alters the microstructural wavelength, or the solids loading can be changed. In doing so, the ratio of pore size to wall size is changed. It is often more prudent to alter the solidification velocity seeing as a minimum solid loading is usually desired. Since microstructural size (λ) is inversely related to the velocity of the freezing front, faster speeds lead to finer structures, while slower speeds produce a coarse microstructure. Controlling the solidification velocity is, therefore, crucial to being able to control the microstructure.
== Adverse effects == Vanillin can trigger migraine headaches in a small fraction of the people who experience migraines. Some people have allergic reactions to vanilla. They may be allergic to synthetically produced vanilla but not to natural vanilla, or the other way around, or to both. Vanilla orchid plants can trigger contact dermatitis, especially among people working in the vanilla trade if they come into contact with the plant's sap. An allergic contact dermatitis called vanillism produces swelling and redness, and sometimes other symptoms. The sap of most species of vanilla orchid which exudes from cut stems or where beans are harvested can cause moderate to severe dermatitis if it comes in contact with bare skin. The sap of vanilla orchids contains calcium oxalate crystals, which are thought to be the main causative agent of contact dermatitis in vanilla plantation workers. A pseudophytodermatitis called vanilla lichen can be caused by handling vanilla pods. It is not caused by vanilla itself but flour mites (Tyroglyphus farinae).
Estrogens can be produced in the brain from steroid precursors. As antioxidants, they have been found to have neuroprotective function. The positive and negative feedback loops of the menstrual cycle involve ovarian estradiol as the link to the hypothalamic-pituitary system to regulate gonadotropins. Estrogen is considered to play a significant role in women's mental health, with links suggested between the hormone level, mood and well-being. Sudden drops or fluctuations in, or long periods of sustained low levels of estrogen may be correlated with significant mood-lowering. Clinical recovery from depression postpartum, perimenopause, and postmenopause was shown to be effective after levels of estrogen were stabilized and/or restored. The volumes of sexually dimorphic brain structures in transgender women were found to change and approximate typical female brain structures when exposed to estrogen concomitantly with androgen deprivation over a period of months, suggesting that estrogen and/or androgens have a significant part to play in sex differentiation of the brain, both prenatally and later in life. There is also evidence the programming of adult male sexual behavior in many vertebrates is largely dependent on estradiol produced during prenatal life and early infancy. It is not yet known whether this process plays a significant role in human sexual behavior, although evidence from other mammals tends to indicate a connection.
=== Initial development === A predecessor compound of minoxidil was developed in the late 1950s by the Upjohn Company (later became part of Pfizer) to treat ulcers. In trials using dogs, the compound did not cure ulcers but proved to be a powerful vasodilator. Upjohn synthesized over 200 variations of the compound, including the one it developed in 1963 and named minoxidil. These studies resulted in the U.S. Food and Drug Administration (FDA) approving minoxidil (with the brand name Loniten) in the form of oral tablets to treat high blood pressure in 1979.
Sources: en.wikipedia.org
Minoxidil — first-line, low dose topical drug for hair loss, can also be used orally at a high dose for hypertension; oral minoxidil has been implicated in heart problems including pericardial effusion. Monoamine oxidase inhibitors — used for treatment-resistant depression; may have potentially lethal dietary and drug interactions which may trigger hypertensive crisis and/or serotonin syndrome. Thalidomide — originally prescribed for morning sickness, withdrawn in 1961 owing to widespread incidence of severe birth defects (phocomelia or tetraamelia) after prenatal use by pregnant women; approved by the US Food and Drug Administration for erythema nodosum leprosum (ENL) in 1998, and new cases of multiple myeloma (administered with dexamethasone) in 2008; also used "off-label" for rare cancers; can cause multiple severe side effects and cannot be prescribed to pregnant women. Tolcapone — used in patients with Parkinson's disease who are not appropriate candidates for other adjunctive therapies; use is restricted due to hepatotoxicity. Vigabatrin — used for extreme treatment-resistant epilepsy; carries risk of permanent vision loss.
When FGF19 was inhibited by specific anti-FGF19 antibodies in monkeys, severe diarrhea was the result. There was also evidence of liver toxicity. Increases in bile acid synthesis, serum and fecal total bile acids, and specific bile acid transporters were found.
April 1 Trump says US military action in Iran could end in "two to three weeks", and that the US will "leave whether we have a deal or not" once he's certain Iran cannot build a nuclear weapon "for years". NASA launches the Artemis II lunar flyby mission from the Kennedy Space Center in Florida, the first crewed flight beyond low Earth orbit since Apollo 17 in 1972. With a crew of four astronauts – Reid Wiseman (commander) Victor Glover (pilot), Christina Koch (mission specialist), and Canadian astronaut Jeremy Hansen (mission specialist) – it also becomes the first time a person of color, a woman, and a non-United States citizen have left low Earth orbit. The Supreme Court hears oral arguments over the constitutionality of Trump's Executive Order 14160 ending birthright citizenship. Trump is in attendance, a first for a sitting president. The DOJ publishes an opinion that the Presidential Records Act is an unconstitutional overreach of congressional power, and advises Trump that he can refuse to hand over records to the National Archives and Records Administration at the end of his term. April 2 Trump fires Attorney General Pam Bondi, who is replaced by Todd Blanche in an acting capacity. Defense Secretary Hegseth fires three high-ranking U.S. Army generals: Chief Staff Randy George, Chief of Chaplins William Green Jr., and T2COM Commander David Hodne. The Pentagon did not provide a reason. The Colorado Court of Appeals vacates the nine-year sentence of 2020 election denier Tina Peters on First Amendment free speech grounds and remands the case for resentencing.
=== Breeder reactors === 238U can produce energy via "fast" fission. In this process, a neutron that has a kinetic energy in excess of 1 MeV can cause the nucleus of 238U to split. Depending on design, this process can contribute some one to ten percent of all fission reactions in a reactor, but too few of the average 2.5 neutrons produced in each fission have enough speed to continue a chain reaction (this is why natural uranium will not work in a bomb). 238U can be used as a source material for creating plutonium-239, which can in turn be used as nuclear fuel. Breeder reactors carry out such a process of transmutation to convert the fertile isotope 238U into fissile 239Pu. It has been estimated that there is anywhere from 10,000 to five billion years worth of 238U for use in these power plants. Breeder technology has been used in several experimental nuclear reactors. By December 2005, the only breeder reactor producing power was the 600-megawatt BN-600 reactor at the Beloyarsk Nuclear Power Station in Russia. Russia later built another unit, BN-800, at the Beloyarsk Nuclear Power Station which became fully operational in November 2016. Also, Japan's Monju breeder reactor, which has been inoperative for most of the time since it was originally built in 1986, was ordered for decommissioning in 2016, after safety and design hazards were uncovered, with a completion date set for 2047. Both China and India have announced plans to build nuclear breeder reactors.
Lente insulin (derived from the Italian word lento, meaning "slow"), also known as insulin zinc suspension, was an intermediate-acting insulin that is no longer used in humans. Its effects begin one to two hours after administration, with peak activity occurring approximately 8 to 12 hours post-injection, and some residual effects lasting beyond 24 hours. Manufacturers discontinued Lente insulin and other similar insulin analogs in the mid-2000s, and it is no longer approved for human use in the United States. This decision was partly due to the medical community's preference for more predictable insulin formulations, such as recombinant NPH insulin. Similarly to the modern brands of NPH and regular insulin, which are still sold, lente insulins would be marketed under the name of the rest of the insulins in a brand's product line, followed by the letter L.
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.
The dry powder is more stable during transport and storage than a solution. It also allows a known amount of material to be reconstituted at a chosen concentration.