Everything below concerns alpha-MSH. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-09-24. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Handling guidance for melanotan II follows general practice for small synthetic peptides rather than a product-specific monograph. Lyophilized powder is typically kept at minus twenty degrees Celsius or colder, protected from light and moisture, because warmth and humidity accelerate degradation. Once reconstituted, solutions are usually refrigerated and used within a short window, as hydrolysis and microbial growth both become concerns. Repeated freeze-thaw cycles are generally avoided. These conventions come from laboratory peptide chemistry and not from formal stability studies on this specific compound.
Analytical confirmation of identity relies on mass spectrometry, most often coupled to liquid chromatography. Reversed-phase high-performance liquid chromatography separates the peptide from related impurities and provides a purity estimate based on peak area. Electrospray ionization mass spectrometry then confirms the expected molecular mass, while tandem mass spectrometry can map the fragment sequence. For research-grade material, these two techniques together form the standard minimum. Purity figures reported by vendors are frequently not traceable to an independent laboratory.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms add to total mass |
| Molecular mass | About 1024 daltons | Calculated for the free base |
| Structural class | Cyclic heptapeptide | Contains D-phenylalanine and norleucine |
| Parent hormone | Alpha-melanocyte-stimulating hormone | Endogenous tridecapeptide of 13 residues |
| Receptor profile | Non-selective melanocortin agonist | Interacts with MC1R, MC3R, MC4R and MC5R |
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.
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.
Melanotan-2 has not received marketing authorisation from major regulatory agencies for any therapeutic indication. Several jurisdictions classify it as a prescription-only medicine or a controlled substance when supplied for human use. Because approved products do not exist, material sold online usually sits outside pharmaceutical supply chains and formal quality oversight. Regulators have issued public notices describing the compound as unapproved. Enforcement varies, and the legal position differs between countries, which complicates any single general statement about its status.
Scientific discussion of Melanotan-2 spans pharmacology, dermatology, and public-health literature. Laboratory studies examine its receptor binding and cellular effects, while clinical reports describe outcomes observed after unregulated use. These two bodies of work differ in rigour and intent. Peer-reviewed trials of the compound as a medicine are limited, so much of the available information comes from case reports and surveillance data. Authors frequently note the gap between experimental findings and real-world use.
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.
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.
== External links == Biological Products at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Debbie Strickland (2007). "Guide to Biotechnology" (PDF). Biotechnology Industry Organization (BIO). Archived from the original (PDF) on 2007-09-27. Retrieved 2007-12-17. Timothy B. Coan; Ron Ellis (2001-06-01). "Report for USA Specialty Pharmaceuticals: Generic Biologics: The Next Frontier" (PDF). Consumer Project on Technology. Retrieved 2007-12-17. "About biologics". National Psoriasis Foundation. 2006-11-01. Archived from the original on 2006-01-01. Retrieved 2007-12-17.
==== Perissodactyl research ==== Tissier & Smith (2026) reconstruct the early evolutionary history of Perissodactyla on the basis of a new phylogenetic study, recovering purported horse relatives Hyracotherium and Pliolophus as not belonging to Hippomorpha, and reporting evidence of rapid dispersals of Pliolophus and Cardiolophus in the northern continents around the Paleocene–Eocene thermal maximum. New fossil material of Ancylotherium hennigi, providing new information on the anatomy of members of this species, is described from the Plio-Pleistocene strata from Laetoli (Tanzania) by Harrison & Kwekason (2026). Radović et al. (2026) identify dental remains of Tapirus arvernensis from the Pliocene strata from the Ridjake fossil site (Serbia). Sun et al. (2026) describe new fossil material of Tapirus sanyuanensis from the Pleistocene strata from Renzidong Cave (Anhui, China), providing information on changes in anatomy of members of this species during their ontogeny, as well as evidence of morphological differences between populations of this species from Renzidong Cave and from the Wushan Longgupo Site (Chongqing, China). Handa et al. (2026) describe rhinocerotid fossils from the Phra Phut sandpit (Thailand), interpreted as indicative of late Miocene age of the studied assemblage, and report evidence of similarity of composition of the studied assemblage and other late Miocene rhinocerotid assemblages from sandpits in Chaloem Phra Kiat District in Nakhon Ratchasima. Sanisidro & Gutiérrez-Marco (2026) describe fossil material of Brachydiceratherium sp.
Wine yeast and LAB competing for resources (including glucose) and potential antagonism between the microbes Heterofermenters such as O. oeni metabolizing the glucose still present in the must and potentially creating undesirable byproducts such as acetic acid Many of the advantages for postalcoholic fermentation answer the disadvantages of early inoculation (namely less antagonism and potential for undesirable byproducts). Also, the advantage is seen of the lees being a nutrient source through the autolysis of the dead yeast cells, though that nutrient source may not always be enough to ensure MLF runs successfully to completion. Conversely, many of the disadvantages of late inoculation are the absence of the advantages that come from early inoculation (higher temperatures, potentially quicker completion, etc.).
Sources: en.wikipedia.org
=== Halide addition === Ethylene oxide readily reacts with aqueous solutions of hydrochloric, hydrobromic, and hydroiodic acids to form halohydrins. The reaction occurs easier with the last two acids:
Ian Goldin professor at University of Oxford, author of over twenty books and 60 scholarly academic monographs, founding director of the Oxford Martin School at the University of Oxford; currently the director of the Oxford Martin Research Programmes on Technological and Economic Change, Future of Work and Future of Development; also Professor of Globalisation and Development and holds a professorial fellowship at Balliol College at the University of Oxford; was principal economist at the European Bank for Reconstruction and Development (EBRD) in London, and program director at the OECD in Paris, where he directed the Development Centre's Programs on Trade, Environment and Sustainable Development; was chief executive and managing director of the Development Bank of Southern Africa (DBSA); served as adviser to President Nelson Mandela; Louis Golding novelist Lawrence Goldman (b.1957) ; historian, academic, Executive Editor of History Reclaimed, journalist; has written for Daily Mail, The Guardian, The Daily Telegraph, was director of the Oxford Dictionary of National Biography and of the Institute of Historical Research, University of London. Vivien Goldman British author and academic of German Jewish ancestry, focusing on the historiography, Praxis (process), dialectic and epistemology of punk rock, dub, and reggae.
== Description == Croton lechleri belongs to the family Euphorbiaceae and are medium-sized trees with evergreen foliage, growing 10 to 20 meters (33 to 66 ft) in height. Despite their relatively large height, the trees have very narrow trunks, averaging a bole diameter of about 30 centimeters (0.98 feet). The leaves are large, alternate cordate (heart-shaped), bright green and 15–30 cm in width and length. The flowers are greenish-white, white or amber, which produce small, three-part capsule fruits that appear on a thin spike that measures 30–50 cm. Both the smooth, mottled bark and viscous, red, latex-rich resin excreted from the wounded trunk of the tree are used medicinally.[9] While the sap can be harvested with a tap much like natural latex from rubber trees, trees that are repeatedly tapped become vulnerable to fungal infections. Croton lechleri are native to the Amazon basin and are distributed across the tropical regions of the South American countries of Bolivia, Brazil, Colombia, Ecuador, Peru, and Venezuela. They are most commonly found in the northwest lowlands between sea level up to 1000 m in elevation, mostly in mineral-rich disturbed soil and along rivers.
Sources: en.wikipedia.org
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.
Melanotan-1, also called afamelanotide, is a linear analogue with greater selectivity for MC1R and has received approval in some jurisdictions for a specific photosensitivity disorder. Melanotan-2 is cyclic, less selective, and reaches central receptors more readily. The two are often confused in online discussion despite different pharmacology and regulatory status.
Alpha-MSH is an endogenous tridecapeptide derived from pro-opiomelanocortin. Melanotan-2 reproduces its core receptor-binding sequence inside a shortened, stabilised ring. The result is a molecule with a longer effective half-life and higher potency than the parent hormone.
The lyophilized powder is generally held at minus twenty degrees Celsius or below, away from light and moisture. Reconstituted solutions are typically refrigerated and used quickly. These practices derive from general peptide handling rather than a formal stability study.