If you have been reading about Melanotan II and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-05-11. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analog of alpha-melanocyte-stimulating hormone |
| Primary receptor family | Melanocortin receptors MC1R through MC5R | Binding is not subtype-selective |
| Development period | 1980s | Synthesized during pigmentation and appetite research |
| Regulatory status | Not an approved medicine | No major regulator has authorized human use |
| Related compound | Afamelanotide | Linear analog studied for photoprotection |
Two structural changes distinguish the synthetic peptide from the natural hormone. A norleucine residue replaces methionine at one position, and a D-configured phenylalanine replaces the natural L-form at another. Both substitutions slow enzymatic breakdown, which extends the molecule's persistence relative to the parent hormone. The lactam bridge further constrains the backbone into a stable conformation. These features are standard design strategies in peptide chemistry and are not unique to this compound; they appear across many research peptides built for improved stability.
The compound was developed in the late 1980s and early 1990s by academic researchers investigating melanocortin signaling and pigmentation. Early work explored whether synthetic analogs could reproduce effects of the natural hormone under controlled conditions. The molecule never advanced through the full regulatory pathway required for approval as a medicine. From the mid-2000s onward it appeared in unregulated consumer markets, often distributed through informal channels. That gap between research origins and commercial availability shapes how the compound is discussed today.
Melanotan II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
Receptor-binding studies classify melanotan II as a non-selective melanocortin agonist. It interacts with MC1R, MC3R, MC4R and MC5R, with reported affinities in the low nanomolar range and no strong subtype preference. Activation of MC1R on dermal melanocytes shifts pigment synthesis toward eumelanin, the dark polymer deposited in melanosomes and transferred to keratinocytes. Because the same peptide engages MC4R in the hypothalamus, it also appears in animal work on food intake and erectile response, which is why it is discussed in both pigment and metabolic research. Which receptor populations dominate after systemic exposure in humans is not fully established.
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.
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.
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.
By 1562 the tulip trade had reached Europe with the first shipment to Antwerp, where they were mistaken for vegetables, although they had been cultivated in Portugal since 1530, and first appeared in illustration in 1559, and the first tulip flowers were seen in the Netherlands in 1625. Tulips spread rapidly across Europe in the seventeenth century, and became an important trading item, initially in France before concentrating in the Netherlands. Eventually speculative trading in tulips became so intense as to cause a financial bubble which eventually collapsed, a period known as tulip mania (tulipomania), from 1634 to 1637, similar to the Ottoman Empire's Tulip era. Nevertheless, since then the tulip has become indelibly associated with the Netherlands and all things Dutch. it was during this period that the tulipiere, a ceramic vase for growing tulips indoors was devised, and the Golden Age of Dutch Painting was replete with images of tulips. Although tulip festivals are held around the world in the spring, the most famous of these is the display at Keukenhof. One of the better-known novels on tulips is The Black Tulip by Alexandre Dumas, père in 1850, dealing with a contest to grow a black tulip in late seventeenth-century Haarlem.
Isobutyryl-coenzyme A is a necessary cofactor required for Polyketide synthase (PKS) enzyme(s), to catalyze the a,b-dehydrogenation of acyl-CoA esters to make many natural products via Polyketide synthase (PKS) assembly lines, as well as PKS-NRPS hybrid assembly lines. The resulting products comprise antibiotics and other bioactive molecules. Notably, isobutyryl-coenzyme A is also an intermediate in the metabolism of the amino acid valine, and it is structurally similar to intermediates in the catabolism of other small amino acids. Defective Isobutyryl-coenzyme A, produced by the body, often results in a metabolic disease.
==== 1400–1499 ==== Valuation Timetable (Scotland) Amendment (No.2) Order 1993 (S.I. 1993/1400) Nene Valley Light Railway (Transfer) Order 1993 (S.I. 1993/1402) Home-Grown Cereals Authority (Rate of Levy) Order 1993 (S.I. 1993/1405) Offshore Installations (Safety Zones) Order 1993 (S.I. 1993/1406) High Court and County Courts Jurisdiction (Amendment) Order 1993 (S.I. 1993/1407) Foreign Fields (Specification) Order 1993 (S.I. 1993/1408) Aeroplane Noise (Limitation on Operation of Aeroplanes) Regulations 1993 (S.I. 1993/1409) Fire Safety and Safety of Places of Sport Act 1987 (Commencement No. 7) Order 1993 (S.I. 1993/1411) Sports Grounds and Sporting Events (Designation) (Scotland) Amendment Order 1993 (S.I. 1993/1412) Food Protection (Emergency Prohibitions) (Paralytic Shellfish Poisoning) (No. 2) Order 1993 (S.I. 1993/1413) Removal, Storage and Disposal of Vehicles (Prescribed Sums and Charges etc.) (Amendment) (No. 2) Regulations 1993 (S.I. 1993/1415) Goods Vehicles (Operators' Licences) (Temporary Use in Great Britain) (Amendment) Regulations 1993 (S.I. 1993/1416) Hackney, Haringey and Islington (London Borough Boundaries) Order 1993 (S.I. 1993/1417) Non-Domestic Rating Act 1993 (Commencement No. 1) Order 1993 (S.I. 1993/1418) Suckler Cow Premium Regulations 1993 (S.I. 1993/1441) Feeding Stuffs (Amendment) Regulations 1993 (S.I. 1993/1442) East London Boroughs (London Borough Boundaries) Order 1993 (S.I. 1993/1443) East London Boroughs (London Borough Boundaries) (No. 2) Order 1993 (S.I. 1993/1444) City and London Borough Boundaries Order 1993 (S.I.
Li2CO3 + CO2 + H2O ⇌ 2 LiHCO3 The extraction of lithium carbonate at high pressures of CO2 and its precipitation upon depressurizing is the basis of the Quebec process. Lithium carbonate can also be purified by exploiting its diminished solubility in hot water. Thus, heating a saturated aqueous solution causes crystallization of Li2CO3. Lithium carbonate, and other carbonates of group 1, do not decarboxylate readily. Li2CO3 decomposes at temperatures around 1300 °C.
=== Nativity === A native antigen is an antigen that is not yet processed by an APC to smaller parts. T cells cannot bind native antigens, but require that they be processed by APCs, whereas B cells can be activated by native ones.
Sources: en.wikipedia.org
In 1997, the Asian financial crisis threatened to devastate Malaysia's economy. The value of the ringgit plummeted due to currency speculation, foreign investment fled, and the main stock exchange index fell by over 75 per cent. At the urging of the International Monetary Fund (IMF), the government cut government spending. It raised interest rates, which only served to exacerbate the economic situation. In 1998, Mahathir defied the IMF's recommendations and implemented bold measures to stabilize the economy. These included pegging the ringgit at RM3.80 to the US dollar, banning offshore trading of the ringgit to curb speculation, and introducing capital controls. Mahathir also launched domestic policies, such as establishing the National Higher Education Fund Corporation (PTPTN) to provide education loans during the crisis. He argued that relying on a floating exchange rate would exacerbate financial speculation and increase the burden of repaying foreign-denominated loans. Concurrently, Mahathir authorized the repatriation of Malaysian assets from abroad. Malaysia recovered from the crisis faster than its Southeast Asian neighbours, aided by an unorthodox capital control policy. The IMF's 1999 Article IV consultation report acknowledged that Malaysia's capital controls and exchange rate peg, initially met with scepticism, had produced more positive results than expected. The report also recognized that Mahathir's policies had helped stabilize the economy, allowing Malaysia to recover faster than many had anticipated.
Ibotenic acid acts as a potent agonist of the NMDA and group I (mGluR1 and mGluR5) and II (mGluR2 and mGluR3) metabotropic glutamate receptors. It is inactive at group III mGluRs. Ibotenic acid also acts as a weak agonist of the AMPA and kainate receptors. In vivo decarboxylation converts ibotenic acid into muscimol, which acts as a potent GABAA and GABAA-ρ receptor agonist. Unlike muscimol—the principal psychoactive constituent of Amanita muscaria that is understood to cause sedation and delirium—ibotenic acid's psychoactive effects are not known independent of its serving as a prodrug to muscimol, although some researchers have speculated that it would act as a stimulant. Ibotenic acid is an agonist of glutamate receptors, specifically at both the N-methyl-D-aspartate, or NMDA, and trans-ACPD receptor sites in multiple systems in the central nervous system. Ibotenic neurotoxicity can be enhanced by glycine and blocked by dizocilpine. Dizocilpine acts as an uncompetitive antagonist at NMDA receptors. Ibotenic acid toxicity comes from activation of the NMDA receptors. NMDA receptors are related to synaptic plasticity and work with metabotropic glutamate receptors to establish long term potentiation or LTP. The process of long term potentiation is believed to be related to the acquisition of information. The NMDA receptor functions properly by allowing Ca2+ ions to pass through after activation at the receptor site.
=== Forum === A major feature of Planet Half-Life, and all other Planet sites was its public forum. These forums included boards ranging from general discussion to technical help. In August 2007, the forums changed format to comply with GameSpy's ForumPlanet standard (the IGN SnowBoards system), removing some outdated features and adding many new ones, such as a dynamic news box that streams in late-breaking news from not only PHL, but all other planet sites as well. This also changed the registration process for the forum, from a per-planet account basis to a network-wide, global account basis. At this time Planet Half-Life's sister sites Planet Fortress and CS.net were officially unsupported and their forums were to be merged into PHL's, although this process lasted over a year before it was complete.
Due to the presence of its valeric acid ester and differences in molecular weight, estradiol valerate contains about 76% of the same amount of estradiol by weight. As a result, 2 mg oral estradiol valerate produces equivalent estradiol levels to about 1.5 mg oral estradiol.
Sources: en.wikipedia.org
No regulator in a major market has approved it for human use. It appears in research settings and in products marketed outside pharmacy channels. Legal status for personal possession varies by country.
Afamelanotide is a linear analog that has received approval in some jurisdictions for a specific photoprotection indication. Melanotan II is cyclic and less selective across melanocortin receptors. The two are related but are not interchangeable in regulatory or clinical terms.
A compound that activates several receptor subtypes may produce effects beyond pigmentation. Selectivity influences which tissues respond and shapes the side-effect profile described in reports. Designing subtype-selective analogs is a stated goal of melanocortin research.
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.