Everything below concerns MC1R. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-12-21. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Reversed-phase high-performance liquid chromatography is the routine method for purity assessment. Peptides absorb near 214 nm because of the peptide bond, and a gradient of acetonitrile in water separates the intact peptide from deletion sequences, oxidised products, and earlier-eluting fragments at neutral pH. Electrospray ionisation mass spectrometry provides an orthogonal check: the measured mass must agree with the theoretical value. Amino acid analysis and peptide mapping confirm structure but are used less often. Reference standards remain scarce because the peptide is not described in any pharmacopoeia.
No regulatory authority has approved melanotan-2 for human use, and several countries classify it as a prescription-only or controlled substance, which restricts lawful supply. Material sold online is generally labelled as a research chemical and is not required to meet pharmaceutical standards of identity or purity. Published human data consist mainly of small uncontrolled studies, case reports and adverse-event notifications, so the evidence base is descriptive rather than confirmatory. Whether repeated melanocyte stimulation alters long-term naevus behaviour remains an open question that no completed trial has resolved.
Melanotan-2 is a synthetic cyclic heptapeptide designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous tridecapeptide that regulates pigment production. Two modifications distinguish it from the natural hormone: norleucine replaces methionine at the N-terminus, which limits oxidation, and a D-phenylalanine substitution raises receptor affinity. The ring is closed through an aspartate-lysine lactam bridge, giving the molecule a constrained conformation. The free base has a molecular mass near 1024 daltons, and commercial material is usually supplied as an acetate salt. It appears in the literature as a research peptide rather than an approved therapeutic agent.
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
| Property | Value | Notes |
|---|---|---|
| Lyophilised storage | −20 °C, dry, protected from light | Vials are sealed and allowed to reach room temperature before opening |
| Reconstituted storage | 2 to 8 °C, protected from light | Short-term holding; avoid repeated freeze-thaw cycles |
| Reconstitution solvent | Water for injection or bacteriostatic water | Added slowly along the vial wall to reduce foaming and shear |
| Purity measurement | RP-HPLC with area normalisation | Acetonitrile-water gradient monitored at roughly 214 nm |
| Identity confirmation | Electrospray ionisation mass spectrometry | Observed mass compared against the calculated peptide mass |
Verification of a purchased sample requires documentation linking a batch to a certificate of analysis, and that document should be read for the methods used rather than the headline purity figure. A single chromatographic percentage does not establish identity. Independent laboratories can perform identity and content assays, but no such test establishes that a product is suitable for human use. Claims about efficacy rest largely on small, early studies rather than on replicated controlled trials, and that gap remains open.
Identity testing for a cyclic peptide of this size usually relies on reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The mass spectrum confirms molecular weight, while the chromatographic trace indicates the proportion of related impurities. Tandem mass spectrometry can provide sequence-level information when fragmentation data are compared against a reference standard. Nuclear magnetic resonance is sometimes used to confirm the lactam bridge, although it requires more material and greater operator expertise than routine chromatographic methods.
Lyophilised peptide powder is comparatively stable when kept dry, cold and protected from light. Once dissolved, the molecule is exposed to hydrolysis, oxidation and microbial growth, and degradation accelerates at higher temperatures and in alkaline solution. Repeated freeze-thaw cycles concentrate solutes and promote aggregation. Handling guidance for research peptides commonly clusters around freezer temperatures for powder and short refrigerated use for reconstituted solutions, with pH control and sterile technique applied throughout.
The peptide was developed during the 1980s by researchers investigating melanocortin signalling and skin pigmentation pathways. Early work focused on analogues of alpha-melanocyte-stimulating hormone that would resist enzymatic breakdown more effectively than the parent molecule. Melanotan-2 emerged from that programme as a shortened, cyclised variant. Reports describing its synthesis and receptor activity later appeared in the scientific literature. Commercial availability grew through unregulated channels rather than through pharmaceutical approval.
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.
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.
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.
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.
Melanotan-2, also written Melanotan II, is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, and the lactam bridge between the aspartate and lysine side chains constrains the peptide into a ring. This structural change increases receptor affinity and metabolic stability relative to the native hormone. The compound was created in the 1980s as a research tool for studying pigmentation biology.
=== Copulation === Copulation begins as the males use their chelicerae to rapidly move back and forth across the female's ventral body surface. This is an attempt to grab hold of the female's body and mount onto their epigyne. For some males, it can take up to 100 attempts to properly mount. Once mounted, the males pull the females closer to them resulting in rotation of the female opisthosoma from a horizontal to vertical position. At this point, the male is able to insert his pedipalps into the genital cavity of the female. During the multiple insertions, the male pedipalps are twisted into different motions in a synchronous fashion with the procursi being inserted deeply into the female genital cavity to release sperm into the uterus externus. As the coupling duration lengthens, the amount of palpal insertions decreases. The duration of copulation is dependent upon whether or not the female P. phalangioides have previously mated with any males. If the females have mated, second males are only allowed to engage in copulation for a few minutes. On the other hand, first males are able to copulate for anywhere between 16 and 122 minutes. Once the mating has finished, the females often act aggressively towards the males in an attempt to drive them off.
TMA-2's affinity (Ki) for the serotonin 5-HT2A receptor has been found to be 1,300 nM. Its EC50Tooltip half-maximal effective concentration at the receptor was 190 nM and its EmaxTooltip maximal efficacy was 84%. The drug was also active at the serotonin 5-HT2B receptor and, to a much lesser extent, at the serotonin 5-HT2C receptor. In an earlier study, its affinities (Ki) were 1,650 nM at the serotonin 5-HT2 receptor and 46,400 nM at the serotonin 5-HT1 receptor. TMA-2 is inactive at the monoamine transporters. It was inactive at the mouse trace amine-associated receptor 1 (TAAR1), whereas it bound to the rat TAAR1 with an affinity (Ki) of 3,100 nM and was not assessed at the human TAAR1.
Although Mr Galloway, Mr Halford and Mr Al-Mukhtar have confirmed that they were unaware of the source of Mr Zureikat's donations, the Commission has concluded that the charity trustees should have made further enquiries when accepting such large single and cumulative donations to satisfy themselves as to their origin and legitimacy. The Commission's conclusion is that the charity trustees did not properly discharge their duty of care as trustees to the Appeal in respect of these donations ... The Commission is also concerned, having considered the totality of the evidence before it, that Mr Galloway may also have known of the connection between the Appeal and the Programme. Galloway, in response, stated: "I've always disputed the Commission's retrospective view that a campaign to win a change in national and international policy – a political campaign – was, in fact, a charity".
==== U.S. regulatory restrictions ==== The US Food and Drug Administration (FDA) position is that red yeast rice products that contain monacolin K are identical to a prescription drug and, thus, subject to regulation as a drug. In 1998, the FDA initiated action to ban a product (Cholestin) containing red yeast rice extract. The U.S. District Court in Utah ruled in favor of allowing the product to be sold without restriction. This decision was reversed on appeal to the U.S. Court of Appeals in 2001. In 2007, the FDA sent warning letters to two dietary supplement companies. One was making a monacolin content claim about its RYR product and the other was not, but the FDA noted that both products contained monacolins. Both products were withdrawn. In a press release the FDA "...is warning consumers to not buy or eat red yeast rice products... may contain an unauthorized drug that could be harmful to health." The rationale for "harmful to health" was that consumers might not understand that the dangers of monacolin-containing red yeast rice are the same as those of prescription statin drugs. A products analysis report from 2010 tested 12 products commercially available in the U.S. and reported that per 600 mg capsule, total monacolins content ranged from 0.31 to 11.15 mg. A 2017 study tested 28 brands of red yeast rice supplements purchased from U.S. retailers, stating "the quantity of monacolin K varied from none to prescription strength". Many of these avoid FDA regulation by not having any appreciable monacolin content.
Because of their costs, many transgender women cannot afford GnRH modulators and must use other, often less effective options for testosterone suppression. However, in countries with publicly funded health care, such as France, they are becoming more common: they are for instance prescribed as standard practice for transgender women in the United Kingdom, where the National Health Service (NHS) covers them. This is in contrast to the United States. Another drawback of GnRH modulators is that most of them are peptides and are not orally active, requiring administration by injection, implant, or nasal spray. However, non-peptide and orally active GnRH antagonists, elagolix (Orilissa) and relugolix (Relumina), were introduced for medical use in 2018 and 2019, respectively. But they are under patent protection and, as with other GnRH modulators, are very expensive at present. In adolescents of either sex, GnRH modulators can be used to suppress puberty. The eighth edition of the World Professional Association for Transgender Health's Standards of Care permit its use from Tanner stage 2 and recommends GnRH agonists as the preferred method of puberty blocking.
Sources: en.wikipedia.org
Jürgen Sundermann (28 May 1991 – 30 June 1993) Bernd Stange (1 July 1993 – 21 February 1994) Jürgen Sundermann (22 February 1994 – 8 April 1994) Damian Halata (9 April 1994 – 30 June 1994) Tony Woodcock (1 July 1994 – 30 October 1994) August "Gustl" Starek (31 October 1994 – 30 May 1996) Damian Halata (1 June 1996 – 30 June 1996) Sigfried "Siggi" Held (1 July 1996 – 7 October 1997) Damian Halata (8 October 1997 – 30 June 1998) Hans-Ulrich "Uli" Thomale (1 July 1998 – 28 March 1999) Dragoslav Stepanović (29 March 1999 – 29 August 1999) Joachim Steffens (30 August 1999 – 22 July 2001) Hans-Jürgen "Dixie" Dörner (23 July 2001 – 26 March 2003) Detlef Schößler (27 March 2003 – 3 June 2003) Hermann Andreev (24 June 2003 – 19 March 2004) Michael Breitkopf and Jörg Engelmann (20 March 2004 – 22 April 2004) Mike Sadlo (23 April 2004 – 30 June 2004) – Player/manager 1. FC Lok Leipzig
In 2022, more than 1 billion adolescent girls and women suffered from undernutrition, according to UNICEF's 2023 report "Undernourished and Overlooked: A Global Nutrition Crisis in Adolescent Girls and Women". The gender gap in food insecurity more than doubled between 2019 (49 million) and 2021 (126 million). The report shows that globally, 30% of women aged 15–49 years are living with anaemia while 10 per cent of women aged 20–49 years suffer from underweight. South Asia, West and Central Africa and Eastern and Southern Africa are home to 60% of women with anaemia and 65% of women being underweight. In contrast, overweight is affecting more than 35% of women aged 20–49 years, of which 13% are living with obesity. The Middle East and North Africa has the highest prevalence of overweight with 61% affected. North America closely follows at 60%. Fewer than 1 in 3 adolescent girls and women have diets meeting the minimum dietary diversity in the Sudan (10%), Burundi (12%), Burkina Faso (17%) and Afghanistan (26%). In Niger, the percentage of women accessing a minimally diverse diet fell from 53% to 37% between 2020 and 2022. Researchers from the Centre for World Food Studies in 2003 found that the gap between levels of undernutrition in men and women is generally small, but that the gap varies from region to region and from country to country. These small-scale studies showed that female undernutrition prevalence rates exceeded male undernutrition prevalence rates in South/Southeast Asia and Latin America and were lower in Sub-Saharan Africa.
He added that efforts were ongoing to secure and defend remote and hard-to-reach areas. Also, on 25 March, two TTP militants were killed in a CTD operation in Tank District. On 27 March, BBC Dari citing satellite imagery, reported that Pakistan had fenced off 32 square kilometers of land in Paktika province, raising speculation that it may have occupied the area. According to BBC Dari, no visible fence line could be seen on 20 March, but by 23 March satellite imagery showed a new fence that had been built 12 kilometers inside Afghan territory. BBC Dari also reported that, after the completion of the first fence line, a second fence was built at the mouth of the same area, more than 13.5 kilometers inside Afghan territory. However, the Afghan Ministry of Defense said that Mali Khan Siddiq, the deputy army chief of the Afghan armed forces, had visited border areas in Paktika and dismissed claims that Pakistani forces had occupied Terwa district as false propaganda. Naseer Ahmad Faiq, Afghanistan's acting Permanent Representative to the UN, said that if reports of Pakistan seizing Afghan territory were true, they would amount to "naked aggression" and should be condemned in the strongest terms. He added that any occupation of Afghan land would be illegal under international law, violate the UN Charter and Afghanistan's territorial integrity, and that Afghanistan's sovereignty was non-negotiable.
Irvine stated that he "criticized Freud and other theorists for projecting male constructs of sexuality onto women" and "viewed the clitoris as the main center of sexual response". He considered the vagina to be "relatively unimportant" for sexual satisfaction, relaying that "few women inserted fingers or objects into their vaginas when they masturbated". Believing that vaginal orgasms are "a physiological impossibility" because the vagina has insufficient nerve endings for sexual pleasure or climax, he "concluded that satisfaction from penile penetration [is] mainly psychological or perhaps the result of referred sensation". Masters and Johnson's research, as well as Shere Hite's, generally supported Kinsey's findings about the female orgasm. Masters and Johnson were the first researchers to determine that the clitoral structures surround and extend along and within the labia. They observed that both clitoral and vaginal orgasms have the same stages of physical response, and found that the majority of their subjects could only achieve clitoral orgasms, while a minority achieved vaginal orgasms. On that basis, they argued that clitoral stimulation is the source of both kinds of orgasms, reasoning that the clitoris is stimulated during penetration by friction against its hood. The research came at the time of the second-wave feminist movement, which inspired feminists to reject the distinction made between clitoral and vaginal orgasms.
== Diagnosis == Parker and colleagues used a variety of standardised neuropsychological tests in their diagnosis of Price's hyperthymesia. These included tests of memory, lateralisation, executive functions, language, calculations, IQ, and visual-spatial and visual-motor functions. They also devised novel tests to examine the extent of her memory abilities. These mostly consisted of questions pertaining to specific dates and events in history. Some of her personal recollections were verified with diary entries, as well as by her mother. Neuroscientist David Eagleman at Stanford University developed a free online test for hyperthymesia (no longer available). Participants first give their year of birth, and then are challenged to match dates to 60 famous events that happened between the time they were five years old and the present day. To qualify as potentially hyperthymestic, participants must achieve a score at least three standard deviations above the average. To prevent people from searching for answers on-line during the test, reaction time for each question is measured; answers must be chosen within 11 seconds to qualify for consideration. However, many of the questions are sourced in American culture and test results could have a strong cultural bias against non-Americans.
Sources: en.wikipedia.org
The lift force is not generated by the air taking the same time to travel above and below an aircraft's wing. This misconception, sometimes called the equal transit-time fallacy, is widespread among textbooks and non-technical reference books, and even appears in pilot training materials. In fact, the air moving over the top of an aerofoil generating lift is always moving much faster than the equal transit theory would imply, as described in the incorrect and correct explanations of lift force.
The carotid sheath is a condensation of the deep cervical fascia enveloping multiple vital neurovascular structures of the neck, including the common and internal carotid arteries, the internal jugular vein, the vagus nerve (CN X), and ansa cervicalis. The carotid sheath helps protects the structures contained therein.
The 3D framework [Cu3(btc)2(H2O)3] (btc: benzene-1,3,5-tricarboxylate) (HKUST-1) used in this study was first reported by Williams et al. The open framework of [Cu3(btc)2(H2O)3] is built from dimeric cupric tetracarboxylate units (paddle-wheels) with aqua molecules coordinating to the axial positions and btc bridging ligands. The resulting framework after removal of two water molecules from axial positions possesses porous channel. This activated MOF catalyzes the trimethylcyanosilylation of benzaldehydes with a low conversion (<5% in 24 h) at 293 K. As the reaction temperature was raised to 313 K, a good conversion of 57% with a selectivity of 89% was obtained after 72 h. In comparison, less than 10% conversion was observed for the background reaction (without MOF) under the same conditions. But this strategy suffers from some problems like 1) the decomposition of the framework with increase of the reaction temperature due to the reduction of Cu(II) to Cu(I) by aldehydes; 2) strong solvent inhibition effect; electron donating solvents such as THF competed with aldehydes for coordination to the Cu(II) sites, and no cyanosilylation product was observed in these solvents; 3) the framework instability in some organic solvents. Several other groups have also reported the use of metal centres in MOFs as catalysts. Again, electron-deficient nature of some metals and metal clusters makes the resulting MOFs efficient oxidation catalysts. Mori and coworkers reported MOFs with Cu2 paddle wheel units as heterogeneous catalysts for the oxidation of alcohols.
=== Biochemistry === In solution, detergents help solubilize a variety of chemical species by dissociating aggregates and unfolding proteins. Popular surfactants in the biochemistry laboratory are sodium lauryl sulfate (SDS) and cetyl trimethylammonium bromide (CTAB). Detergents are key reagents to extract protein by lysis of the cells and tissues: they disorganize the membrane's lipid bilayer (SDS, Triton X-100, X-114, CHAPS, DOC, and NP-40), and solubilize proteins. Milder detergents such as octyl thioglucoside, octyl glucoside or dodecyl maltoside are used to solubilize membrane proteins such as enzymes and receptors without denaturing them. Non-solubilized material is harvested by centrifugation or other means. For electrophoresis, for example, proteins are classically treated with SDS to denature the native tertiary and quaternary structures, allowing the separation of proteins according to their molecular weight. Detergents have also been used to decellularise organs. This process maintains a matrix of proteins that preserves the structure of the organ and often the microvascular network. The process has been successfully used to prepare organs such as the liver and heart for transplant in rats. Pulmonary surfactants are also naturally secreted by type II cells of the lung alveoli in mammals.
Sources: en.wikipedia.org
Low temperature slows hydrolysis and oxidation, the two main routes by which the peptide backbone and side chains are modified. A lyophilised powder stored at −20 °C is more stable than one kept at room temperature, and once the material is dissolved the degradation rate rises, making refrigeration more important.
Liquid chromatography coupled to mass spectrometry is the most common approach because it combines a retention time with a mass measurement. A chromatographic peak alone cannot establish which peptide is present, so mass determination or amino acid analysis is used as an orthogonal confirmation alongside the separation.
This depends on buffer, pH, and concentration, and published stability data for this peptide are limited. In practice laboratories work through a refrigerated solution within a few weeks and discard samples that show cloudiness or visible particles. Freezing and thawing repeatedly is generally discouraged.
No regulatory agency has authorised melanotan-2 as a medicine for any indication. It circulates mainly as a research chemical or through unregulated channels. As a result, identity, purity and content are not independently guaranteed.