This is a working overview of melanocortin receptor, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-06-04. Anything still debated is marked as such rather than presented as settled.
Melanotan II is a synthetic peptide analog modeled on alpha-melanocyte-stimulating hormone, a naturally occurring signaling peptide involved in pigmentation. Its structure is a cyclic heptapeptide containing two non-natural substitutions, norleucine at position four and D-phenylalanine at position seven. These modifications resist enzymatic breakdown and extend the molecule's activity relative to the native hormone. The compound binds melanocortin receptors and is studied mainly as a pharmacological tool rather than a therapeutic product. It has never received approval as a medicine in any major jurisdiction.
The compound was developed in the late 1980s and 1990s by academic researchers investigating photoprotection. The rationale held that stimulating melanin production might reduce ultraviolet damage to skin and lower skin cancer risk. Early work examined receptor binding, pigment response, and short-term tolerability in small studies. That program did not produce an approved drug, and formal development stalled after early-phase trials. Whether induced pigmentation confers meaningful photoprotection remains an open question.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Belongs to the melanocortin agonist family |
| Key substitutions | Nle4 and D-Phe7 | Improve resistance to enzymatic degradation |
| Molecular formula | C50H69N15O9 | Approximately 1024 g/mol |
| Regulatory status | Not approved as a medicine | Distributed as a research chemical |
| Common synonyms | Melanotan II, MT-II, MT-2 | Spelling varies across sources |
=== Dry granular flows === Under certain circumstances, flows of granular materials can be modelled as a continuum, for example using the μ(I) rheology. Such continuum models tend to be non-Newtonian, since the apparent viscosity of granular flows increases with pressure and decreases with shear rate. The main difference is the shearing stress and rate of shear.
==== Phosphorylated tau ==== Alzheimer's disease is also considered a tauopathy due to the abnormal aggregation of the tau protein within cells. Every neuron has a cytoskeleton, an internal support structure partly made up of organelles called microtubules. These microtubules act like tracks, guiding nutrients and molecules from the body of the cell to the ends of the axon and back. The tau protein stabilises the microtubules when phosphorylated, and it is therefore called a microtubule-associated protein. In Alzheimer's disease, tau undergoes chemical changes, becoming hyperphosphorylated; it then begins to pair with other threads, creating neurofibrillary tangles and disintegrating the neuron's transport system. Pathogenic tau can also cause neuronal death through transposable element dysregulation. Necroptosis has also been reported as a mechanism of cell death in brain cells affected with tau tangles.
He has advocated for better media representation of clinical laboratories and is developing a television drama series centered on a clinical laboratory director and his team of scientists solving medical cases using diagnostic tools. He has drawn comparisons between the potential impact of a lab-focused TV show and the forensic science popularity surge following programs such as CSI and NCIS.
Sources: en.wikipedia.org
== Books == Mager, A.K. (1999) Gender and the Making of a South African Bantustan: A Social History of the Ciskei, 1945–1959, Heinemann. Switzer, L. (1993) Power and Resistance in an African Society: The Ciskei Xhosa and the Making of South Africa, University of Wisconsin Press.
Portugal's legislative body is the Assembly of the Republic, a unicameral parliament. It consists of a single chamber with a minimum of 180 seats and a maximum of 230, elected by popular vote every four years or when dissolved. The members of parliament represent the whole country and not the constituencies for which they are elected. The Assembly of the Republic is dominated by three political parties, the Social Democratic Party (PSD), Chega (CH), and the Socialist Party (PS). As the head of government, the prime minister directs government policy, leads the Council of Ministers which includes ministers and junior ministers that execute government policy, and is appointed by the president in light of electoral results after consulting with the parties with parliament seats. Portugal's current prime minister is Luís Montenegro, who took office after the AD – PSD/CDS Coalition won enough seats to form a minority government following the 2024 Portuguese legislative election. Portugal has a civil law system based on Roman law and on Canon Law and influenced by German civil law. The Constitution is the supreme law of Portugal. In the Portuguese legal system, private civil law and criminal law are codified in the Código Civil and the Código Penal respectively. Portugal's court system is organised into judicial, administrative, and fiscal branches with three levels of jurisdiction and separate courts of last appeal, while the Constitutional Court is responsible for constitutional review and oversight of elections, referendums and political parties.
Dahlgren (1985) suggested there were in fact forty – not one – families distributed over three orders (predominantly Liliales and Asparagales). In the context of a general review of the classification of angiosperms, the Liliaceae were subjected to more intense scrutiny. Considerable progress in plant phylogeny and phylogenetic theory enabled a phylogenetic tree to be constructed for all of the flowering plants, as elaborated by the Angiosperm Phylogeny Group (1998).
Sources: en.wikipedia.org
=== Industry === Formaldehyde is produced industrially by the catalytic oxidation of methanol. The most common catalysts are silver metal (i.e. the FASIL process), iron(III) oxide, iron molybdenum oxides (e.g. iron(III) molybdate) with a molybdenum-enriched surface, or vanadium oxides. In the commonly used formox process, methanol and oxygen react at c. 250–400 °C in presence of iron oxide in combination with molybdenum or vanadium to produce formaldehyde according to the chemical equation
== Early life and education == Born in Dublin, the youngest son of Henry Horatio Dixon, he was interested in science from a young age; his discovery of an optical illusion arising from binocular vision was described by his father in Nature Magazine when he was only nine years old. After education at Shrewsbury School he was awarded a scholarship in 1946 to study Natural Sciences at King's College, Cambridge where his elder brother Kendal was a fellow, achieving firsts in Part I and Part II and specialising in biochemistry. He remained at King's for his graduate studies on peptide hormones, supervised by Frank Young, and was awarded a Ph.D. in 1954.
== Function == Morpholinos do not trigger the degradation of their target RNA molecules, unlike many antisense structural types (e.g., phosphorothioates, siRNA). Instead, Morpholinos act by "steric blocking", binding to a target sequence within an RNA, inhibiting molecules that might otherwise interact with the RNA. Morpholino oligos are often used to investigate the role of a specific mRNA transcript in an embryo. Developmental biologists inject Morpholino oligos into eggs or embryos of zebrafish, African clawed frog (Xenopus), sea urchin and killifish (F. heteroclitus) producing morphant embryos, or electroporate Morpholinos into chick embryos at later development stages. With appropriate cytosolic delivery systems, Morpholinos are effective in cell culture. Vivo-Morpholinos, in which the oligo is covalently linked to a delivery dendrimer, enter cells when administered systemically in adult animals or in tissue cultures. Gene knockdown is achieved by reducing the expression of a particular gene in a cell. In the case of protein-coding genes, this usually leads to a reduction in the quantity of the corresponding protein in the cell. Knocking down gene expression is a method for learning about the function of a particular protein; in a similar manner, causing a specific exon to be spliced out of the RNA transcript encoding a protein can help to determine the function of the protein moiety encoded by that exon or can sometimes knock down the protein activity altogether.
Sources: en.wikipedia.org
It is a synthetic cyclic peptide designed as an analog of alpha-melanocyte-stimulating hormone. It acts on melanocortin receptors and is best known from research into pigmentation. It is not an approved pharmaceutical product.
No regulatory agency has approved it for any indication. It is encountered as a research chemical sold outside pharmaceutical supply chains. Products marketed this way are not subject to the manufacturing and labeling requirements that apply to approved drugs.
Reports describe increased skin pigmentation as well as side effects such as nausea, flushing, and changes to existing moles. Much of the evidence comes from small studies and case reports rather than large trials. The long-term safety profile is therefore uncertain.
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.