The short version of melanotan II fits in a sentence. The long version — which is the one that helps — is below.
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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.
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 II is a synthetic cyclic heptapeptide that acts as an agonist at melanocortin receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide involved in pigment production. The analogue carries a lactam bridge that constrains the ring and slows enzymatic breakdown relative to the native hormone. In research literature it appears under several abbreviations, and naming conventions are not fully standardized. Published descriptions usually place it within the broader melanocortin agonist family.
| 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 |
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.
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.
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.
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.
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-2 is a synthetic peptide designed as an analog of alpha-melanocyte-stimulating hormone, a signaling molecule produced in the pituitary and skin. Its structure is a linear chain of seven amino acids that folds into a ring through an internal lactam bridge joining two side chains. The compound is sometimes written as MT-II or MEL-2 in informal and commercial contexts. It belongs to the melanocortin peptide family, a group of short signaling molecules that share a conserved core sequence recognized by melanocortin receptors.
The jalapeño is variously named huachinango, for the ripe red jalapeño, and chile gordo (meaning "fat chili pepper") also known as cuaresmeño. The name jalapeño is Spanish for "from Xalapa", the capital city of Veracruz, Mexico. Contrary to popular belief, the jalapeño pepper is not grown in or around Xalapa, but Vicente Jiménez invented the process of pickling and canning the peppers in Xalapa. Genetic analysis of Capsicum annuum places jalapeños as a distinct genetic clade with no close sisters that are not directly derived from jalapeños. Jalapeños were in use by the Aztecs prior to the Spanish conquest; Bernardino de Sahagún in the Florentine Codex writes of Aztec markets selling chipotles (smoked jalapeños) and mole made from chipotles, besides the sale of fresh chilies. The use of peppers in the Americas dates back thousands of years, including the practice of smoking some varieties of peppers in order to preserve them; further well preserved samples and genetic testing would be needed to determine the usage and existence of the jalapeño clade and pod type in the past.
== Reactions == The cycle comprises three enzyme-catalysed reactions. The first stage is the deamination of the purine nucleotide adenosine monophosphate (AMP) to form inosine monophosphate (IMP), catalysed by the enzyme AMP deaminase:
During this period, Aden became important for British military and commercial purposes in the region, as well as a base for the Royal Navy and the Royal Air Force. The colony's surrounding hinterland, was governed separately as the Aden Protectorate. By the early 1960s, widespread dissatisfaction with British rule led to the Aden Emergency, a violent uprising against colonial authorities. In 1963, Aden Colony was reconstituted as the State of Aden within the newly created Federation of South Arabia in an attempt to grant limited self-governance, but the unrest continued. The British withdrew in 1967, and the colony was succeeded by the People's Republic of Southern Yemen, marking the end of British control after 128 years of rule.
Shorter D-stem: To understand the role of the unusual long D-stem in tRNASec, artificial variants with shorter D-stems were put into E. coli. It turns out that these variants work faster than the standard version at regular temperatures but easily lose function at high temperatures. This suggests that the long D-stem evolved as an adaptation to high temperature. Removal of SelB and SECIS requirement: In 2013, a new kind of tRNA was artificially created by putting the acceptor stem and CUA anticodon of E. coli tRNASec on the backbone of E. coli tRNASer. This new tRNAUTu can be recognized by ordinary EF-Tu, removing the requirement for SelB and SECIS for elongation. However, about 40% of the insertions were serine instead of selenocystine, suggesting that SelA is not efficiently recognizing this tRNA. In 2014, directed evolution was used to greatly improve the ability of tRNAUTu to be recognized by SelA, achieving a version that results in no detected misincorporation of serine. This enables simple replacement of any residue by Sec in future protein engineering efforts. By 2018, the E. coli system has matured to be suitable for "industrial scale" production. In one case this was achieved by laborotaory evolution. In another case this was achieved by incorporating elements of allo-tRNAs. The tRNAUTu system was adapted to Saccharomyces cerevisiae (yeast), which has no natural selenocystine system, in 2023. A mixture of bacterial and mouse enzymes work on a modified yeast tRNASer, which is able to be recognized by eEF1A.
=== UNGASS guidance === Three Special Session of the United Nations General Assembly (UNGASS) sessions have been held on the subject of drugs: "Drug abuse" (1990), "World drug problem" (1998), and "World drug problem" (2016). These high-level gatherings, involving heads of state and ministers, are documented usually in the form of a political declaration, an action plan, or a strategy that provide additional treaty guidance. These sessions can indicate whether the status quo will be maintained or if there is a broad openness to reform. In March 2016, the INCB stated that the UN drug treaties do not mandate a "war on drugs" and that the choice is not between "'militarized' drug law enforcement on one hand and the legalization of non-medical use of drugs on the other", health and welfare should be the focus of drug policy. That April, at the UNGASS on the "World drug problem", the Wall Street Journal assessed the attendees' positions as "somewhat" in two camps: "Some European and South American countries as well as the U.S. favored softer approaches.
Sources: en.wikipedia.org
Homochirality is a uniformity of chirality, or handedness. Objects are chiral when they cannot be superposed on their mirror images. For example, the left and right hands of a human are approximately mirror images of each other but are not their own mirror images, so they are chiral. In chemistry, chirality is a geometric property of some compounds and ions. These compounds exist in two different chiral conformations, enantiomers, often described as the left-handed and right-handed isomers of a compound (denoted by L- (levorotatory to the left) and D- (dextrorotatory to the right), respectively, from how chiral molecules rotate plane-polarized light). The term homochiral is used to describe enantiopure samples of substances in which all the constituents are the same enantiomer. Enantiomers have the same chemical properties in an achiral environment, so abiotic chemical processes typically produce racemic mixtures of chiral compounds, i.e., mixtures containing equal amounts of L- and D-isomers. However, many biologically-synthesized compounds are homochiral. For example, 19 of the 20 genetically-coded proteinogenic amino acids are left-handed, with exception of the achiral glycine, and biological sugars are right-handed. Many theories have been proposed for the "function" of homochirality in nature: it may be a form of information storage and may reduce entropy barriers in the formation of large organized molecules. It has been experimentally verified that amino acids form large aggregates in larger abundance from enantiopure samples than from racemic ones.
Although the mechanical properties of the synthetic skin do not need to be exactly the same as human, the main ones that should be similar include modulus of elasticity, tear strength, and fracture energy.
=== Orientational anisotropy === SHG polarization anisotropy can be used to determine the orientation and degree of organization of proteins in tissues since SHG signals have well-defined polarizations. By using the anisotropy equation:
Lungs Some impairment in lung function is almost universally seen in patients with diffuse scleroderma on pulmonary function testing, but it does not necessarily cause symptoms, such as shortness of breath. Some patients can develop pulmonary hypertension, or elevation in the pressures of the pulmonary arteries. This can be progressive, and can lead to right-sided heart failure. The earliest manifestation of this may be a decreased diffusion capacity on pulmonary function testing. Other pulmonary complications in more advanced disease include aspiration pneumonia, pulmonary hemorrhage and pneumothorax.
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.
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.