Everything below concerns research chemical. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-03-18. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Outside regulated medicine, melanotan II circulates through online vendors as a research chemical, often marketed for tanning. Products sold this way vary widely in purity, concentration, and labeling accuracy, and independent testing has documented discrepancies. Published reports describe both pigment effects and adverse reactions, including nausea, flushing, and darkening of existing moles. Long-term safety data are sparse, and no large controlled trial has established a risk profile. Questions about cumulative effects on melanocytes remain unresolved in the literature.
Solid peptide material is generally stable when kept cold and dry. Common practice is storage at -20 degrees Celsius or lower, with desiccant and protection from light. Repeated freeze-thaw cycles and exposure to moisture are associated with degradation, aggregation, or loss of material. Once dissolved, stability depends on solvent, concentration, and temperature, and solutions are usually treated as short-lived unless stability data support longer periods. Handling notes typically emphasise minimising time at ambient temperature.
Identity and purity are assessed with chromatographic and mass spectrometric techniques. Reversed-phase high-performance liquid chromatography separates the target peptide from related impurities and degradation products, and the resulting retention time is compared against a reference standard. Mass spectrometry, often coupled to liquid chromatography, confirms molecular mass. Amino acid analysis or peptide mapping can provide additional sequence-level confirmation when required. Results are only as reliable as the reference materials used alongside them.
Regulatory treatment varies by country. In the United States, melanotan-2 is not approved for any indication, and products marketed for human use fall outside the approved drug framework. Some other jurisdictions have placed it under prescription controls or listed it as a prohibited or restricted substance. Online listings frequently describe the material as a research chemical, a category that does not carry the same manufacturing and labelling requirements as approved medicines.
| 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 |
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.
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.
Identity testing for a synthetic peptide relies on several complementary methods. Reversed-phase high-performance liquid chromatography separates the target from related impurities and reports purity as a percentage of total peak area. Mass spectrometry confirms molecular mass and can reveal deletions or truncations. Amino acid analysis and peptide mapping provide sequence-level confirmation, while counter-ion content and residual solvents are measured separately. A purity figure alone does not establish identity, so a complete dataset combines chromatographic and spectrometric evidence.
Lyophilized peptide powder is generally stored frozen, protected from light and moisture. Tryptophan residues are susceptible to oxidation, and the lactam bridge can hydrolyze under strongly acidic or basic conditions. Solutions prepared for laboratory work degrade faster than dry powder, and repeated freeze-thaw cycles accelerate loss. Common practice is to aliquot solutions before freezing and to avoid alkaline buffers. Reported stability windows vary with concentration, buffer, and temperature, so exact shelf lives are method-specific rather than universal.
The enzyme was incorrectly classified as acting on a CH-OH group EC 1.1.3.23: Thiamine oxidase EC 1.1.3.24: L-galactonolactone oxidase EC 1.1.3.25: Now included with EC 1.1.99.18, cellobiose dehydrogenase (acceptor) EC 1.1.3.26: Now EC 1.21.3.2, columbamine oxidase EC 1.1.3.27: hydroxyphytanate oxidase EC 1.1.3.28: nucleoside oxidase EC 1.1.3.29: N-acylhexosamine oxidase EC 1.1.3.30: polyvinyl-alcohol oxidase EC 1.1.3.31: deleted, cannot be distinguished from EC 1.1.3.13, alcohol oxidase EC 1.1.3.32: Now EC 1.14.21.1, (S)-stylopine synthase EC 1.1.3.33: Now EC 1.14.21.2, (S)-cheilanthifoline synthase EC 1.1.3.34: Now EC 1.14.21.3, berbamunine synthase EC 1.1.3.35: Now EC 1.14.21.4, salutaridine synthase EC 1.1.3.36: Now EC 1.14.21.5, (S)-canadine synthase EC 1.1.3.37: D-arabinono-1,4-lactone oxidase EC 1.1.3.38: vanillyl-alcohol oxidase EC 1.1.3.39: nucleoside oxidase (H2O2-forming) EC 1.1.3.40: D-mannitol oxidase EC 1.1.3.41: xylitol oxidase EC 1.1.3.42: prosolanapyrone-II oxidase EC 1.1.3.43: paromamine 6′-oxidase EC 1.1.3.44: 6′′′-hydroxyneomycin C oxidase EC 1.1.3.45: aclacinomycin-N oxidase EC 1.1.3.46: 4-hydroxymandelate oxidase EC 1.1.3.47: 5-(hydroxymethyl)furfural oxidase EC 1.1.3.48: 3-deoxy-α-D-manno-octulosonate 8-oxidase EC 1.1.3.49: (R)-mandelonitrile oxidase
Medical conditions that can cause joint hypermobility include FASDs, Stickler syndrome, Ehlers–Danlos syndrome, Marfan syndrome, Loeys–Dietz syndrome, rheumatoid arthritis, osteogenesis imperfecta, lupus, polio, Fragile X syndrome, Down syndrome, Morquio syndrome, cleidocranial dysostosis and myotonia congenita. All have other diagnostic criteria as well. Current thinking suggests four causative factors:
Phosphagens, also known as macroergic compounds, are high energy storage compounds, also known as high-energy phosphate compounds, chiefly found in muscular tissue in animals. They allow a high-energy phosphate pool to be maintained in a concentration range, which, if it all were adenosine triphosphate (ATP), would create problems due to the ATP-consuming reactions in these tissues. As muscle tissues can have sudden demands for much energy, these compounds can maintain a reserve of high-energy phosphates that can be used as needed, to provide the energy that could not be immediately supplied by glycolysis or oxidative phosphorylation. Phosphagens supply immediate but limited energy. The actual biomolecule used as a phosphagen is dependent on the organism. The majority of animals use arginine as phosphagen; however, the phylum Chordata (i.e., animals with spinal cords) use creatine. Creatine phosphate (CP), or phosphocreatine (PCr), is made from ATP by the enzyme creatine kinase in a reversible reaction:
Sources: en.wikipedia.org
ω (omega) is the angle in the chain Cα − C' − N − Cα, φ (phi) is the angle in the chain C' − N − Cα − C' ψ (psi) is the angle in the chain N − Cα − C' − N (called φ′ by Ramachandran) The figure at right illustrates the location of each of these angles (but it does not show correctly the way they are defined). The planarity of the peptide bond usually restricts ω to be 180° (the typical trans case) or 0° (the rare cis case). The distance between the Cα atoms in the trans and cis isomers is approximately 3.8 and 2.9 Å, respectively. The vast majority of the peptide bonds in proteins are trans, though the peptide bond to the nitrogen of proline has an increased prevalence of cis compared to other amino-acid pairs. The side chain dihedral angles are designated with χn (chi-n). They tend to cluster near 180°, 60°, and −60°, which are called the trans, gauche−, and gauche+ conformations. The stability of certain sidechain dihedral angles is affected by the values φ and ψ. For instance, there are direct steric interactions between the Cγ of the side chain in the gauche+ rotamer and the backbone nitrogen of the next residue when ψ is near −60°. This is evident from statistical distributions in backbone-dependent rotamer libraries. Dihedral angles have also been defined by the IUPAC for other molecules, such as the nucleic acids (DNA and RNA) and for polysaccharides.
Slavery in Korea existed since before the Three Kingdoms of Korea period, in the first century BCE. Slavery has been described as "very important in medieval Korea, probably more important than in any other East Asian country, but by the 16th century, population growth was making [it] unnecessary". Slavery went into decline around the 10th century but came back in the late Goryeo period when Korea also experienced multiple slave rebellions. In the Joseon period of Korea, members of the slave class were known as nobi. The nobi were socially indistinct from freemen (i.e., the middle and common classes) other than the ruling yangban class, and some possessed property rights, and legal and civil rights. Hence, some scholars argue that it is inappropriate to call them "slaves", while some scholars describe them as serfs. The nobi population could fluctuate up to about one-third of the total, but on average the nobi made up about 10% of the total population. In 1801, the majority of government nobi were emancipated, and by 1858, the nobi population stood at about 1.5 percent of the Korean population. During the Joseon period, the nobi population could fluctuate up to about one-third of the population, but on average the nobi made up about 10% of the total population. The nobi system declined beginning in the 18th century. Since the outset of the Joseon dynasty and especially beginning in the 17th century, there was harsh criticism among prominent thinkers in Korea about the nobi system.
==== Entertainment industry ==== Glycerol is used by set decorators when filming scenes involving water to prevent an area meant to look wet from drying out too quickly. Glycerine is also used in the generation of theatrical smoke and fog as a component of the fluid used in fog machines as a replacement for glycol, which has been shown to be an irritant if exposure is prolonged.
Sources: en.wikipedia.org
== Food chain versus food web == A food chain differs from a food web as a food chain follows a direct linear pathway of consumption and energy transfer. Natural interconnections between food chains make a food web, which are non-linear and depict interconnecting pathways of consumption and energy transfer.
Parathyroid hormone regulates serum calcium through its effects on bone, kidney, and the intestine: In bone, PTH enhances the release of calcium from the large reservoir contained in the bones. Bone resorption is the normal destruction of bone by osteoclasts, which are indirectly stimulated by PTH. Stimulation is indirect since osteoclasts do not have a receptor for PTH; rather, PTH binds to osteoblasts, the cells responsible for creating bone. Binding stimulates osteoblasts to increase their expression of RANKL and inhibits their secretion of osteoprotegerin (OPG). Free OPG competitively binds to RANKL as a decoy receptor, preventing RANKL from interacting with RANK, a receptor for RANKL. The binding of RANKL to RANK (facilitated by the decreased amount of OPG available for binding the excess RANKL) stimulates osteoclast precursors, which are of a monocyte lineage, to fuse. The resulting multinucleated cells are osteoclasts, which ultimately mediate bone resorption. Estrogen also regulates this pathway through its effects on PTH. Estrogen suppresses T cell TNF production by regulating T cell differentiation and activity in the bone marrow, thymus, and peripheral lymphoid organs. In the bone marrow, estrogen downregulates the proliferation of hematopoietic stem cells through an IL-7-dependent mechanism. In the kidney, around 250 mmol of calcium ions are filtered into the glomerular filtrate per day. Most of this (245 mmol/d) is reabsorbed from the tubular fluid, leaving about 5 mmol/d to be excreted in the urine.
Prior to the development of biological therapy as a modality to treat IBD, other medications that modulate the immune system—including 5-aminosalicylates, steroids, azathioprine, and other immunosuppressants—were primarily used in treatment. Corticosteroids are effective in inducing clinical remission in patients with active IBD, but they can't be used long term due to the risk of steroid-dependence and harsh side effects. The other medications like 5-aminosalicylates and azathioprine are often used to reduce steroid use while maintaining remission, but their actual effect on the state of the disease and the need for surgery remains unknown. Patients with Crohn's disease that developed complications, including fistulae (= abnormal connections to the bowel) were treated with surgery. Patients with ulcerative colitis who do not respond to medications are still treated with colectomy (= removal of the colon). However, basic science research showed that many cytokines were elevated in both Crohn's disease and ulcerative colitis. Crohn's disease cytokines are of the type 1 (Th1) cytokines, which include TNF-α, interleukin-2, and interferon γ. Ulcerative colitis was less conclusively linked to the production of Th2 cytokines. TNF inhibiting biological therapies were initially used in IBD patients who weren't responding to conventional therapy. They proved to be very effective in some patients, shifting treatment goals from simply improving symptoms to actually changing the course of the disease by reversing mucosal inflammation and preventing long-term complications and surgery.
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.
Laboratory confirmation typically combines retention time matching on a chromatographic system with mass measurement. A reference standard of known identity is needed for a meaningful comparison. Sequence-level techniques can add further confirmation.