Everything below concerns cyclic heptapeptide. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-02-23. Numbers and descriptions here follow the published literature rather than marketing material.
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 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.
Pharmacologically, melanotan-2 behaves as a non-selective agonist across the melanocortin receptor family. Binding at MC1R on dermal melanocytes promotes eumelanin synthesis, which underlies the tanning response described in early human work. Activity at the centrally expressed MC4R receptor is associated with reported effects on appetite and erectile function. Because the peptide does not discriminate strongly among receptor subtypes, attributing any single observed effect to one receptor pathway is generally not possible without selective antagonists or receptor knockout models.
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.
| Property | Value | Notes |
|---|---|---|
| Regulatory status | Unapproved for therapeutic use | No marketing authorisation from major agencies |
| Legal classification | Varies by jurisdiction | Prescription-only or controlled in several countries |
| Common synonyms | Melanotan II; MT-II | Also referenced by catalogue codes |
| Typical analytical method | Reverse-phase HPLC | Often paired with mass spectrometry |
| Primary literature focus | Receptor pharmacology | Pigmentation and melanocortin signalling |
Solid peptide kept dry at minus twenty degrees Celsius, shielded from light and moisture, is generally considered stable for extended periods. Solutions are divided into single-use aliquots and held at minus twenty or minus eighty degrees Celsius, because repeated freeze-thaw cycles promote aggregation and loss of material to container surfaces. Hydrolysis of the backbone and oxidation of tryptophan are the principal degradation routes in aqueous solution, and both accelerate at ambient temperature. Hygroscopic uptake after a vial is opened can also shift the actual mass weighed, which affects any concentration calculated from it.
Routine characterisation relies on reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, using a C18 column and a water-acetonitrile gradient containing trifluoroacetic acid. Electrospray ionisation mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidised by-products that co-elute poorly. Sequence and stereochemistry require additional work, such as peptide mapping or amino acid analysis, because a chromatographic purity figure alone does not distinguish a diastereomer from the target peptide. Independent testing of research-grade material frequently shows measured content below the stated label, so a certificate of analysis is best read together with the method that produced it.
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.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, which separates the target peptide from truncated or oxidised impurities. Mass spectrometry, most often coupled to liquid chromatography, confirms molecular mass and detects substitutions that chromatography alone may miss. Amino acid analysis and peptide mapping supply additional structural evidence, while nuclear magnetic resonance is reserved for full structural confirmation. Laboratories that examine samples sold online report wide variation in actual content, with some vials containing little or none of the labelled material.
Melanotan-2 appears on the World Anti-Doping Agency prohibited list within the peptide hormone class, and several national regulators treat it as an unapproved prescription substance. Some countries restrict importation or sale for personal use. Because the compound is widely traded as a research chemical, the practical legal picture differs between jurisdictions and shifts over time. Human safety data covering long periods are limited, and whether repeated pigmentation changes carry any lasting risk to melanocytes remains an open question.
Freeze-dried melanotan-2 is normally kept as a desiccated powder at minus twenty degrees Celsius or lower, shielded from light and moisture. Peptides of this size degrade through hydrolysis, oxidation and deamidation, and each pathway accelerates as temperature and water activity rise. Repeated freeze-thaw cycles promote aggregation and loss of material, so aliquoting a stock solution before freezing is standard laboratory practice. Once dissolved, the solution is markedly less stable than the powder. In laboratory work, solutions are generally refrigerated and used within days rather than kept for months.
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.
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.
== External links == UniProt: Bisphosphoglycerate mutase - Homo sapiens (Human) UniProt-Information about bisphosphoglycerate mutase A live model of the effect of changing 2,3-bisphosphoglycerate on the oxyhaemoglobin saturation curve
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Sources: en.wikipedia.org
Senate delegation to visit China during the second Trump presidency, with the group traveling to Beijing and Shanghai to meet Chinese officials and visit technology companies. On 7 May, Chinese premier Li Qiang and National People's Congress Standing Committee chairman Zhao Leji separately met with the delegation in Beijing.
== S == sarcoplasmic reticulum - satellite DNA - scientific notation - SDS-PAGE - second messenger - second messenger system - secondary structure - secretin - selectin - sensory receptor - sequence (biology) - sequence homology - sequence motif - sequencing - serine - serotonin - serotonin receptor - serpin - sexual reproduction - SH3 domain - SI - sigma factor - signal peptide - signal recognition particle - signal sequence - signal transduction - sincalide - skeleton - skin - smooth ER - sodium channel - sodium-hydrogen antiporter - soluble - solution - solvation - solvent - somatomedin - somatomedin receptor - somatostatin - somatostatin receptor - somatotropin - somatotropin receptor - somatotropin-releasing hormone - somatropin - sp1 transcription factor - spectrin - spectroscopy - src gene - src-family kinase - SSRI - starch - stem cell - stereochemistry - steroid 17alpha-monooxygenase - steroid 21-monooxygenase - steroid receptor - stimulatory gs G-protein - stoichiometry - structural biology - structural domain - Structural formula - structural motif - substance P - substrate - sugar - sulfur - supercoil - superfamily - superoxide - surface immunoglobulin - surface plasmon resonance - suspension (chemistry) - synapse - synthetic vaccine - systems biology
A κ-opioid receptor agonist, or simply KOR agonist or kappa agonist, is a drug which acts as an agonist of the κ-opioid receptor (KOR), the target of the endogenous dynorphin peptides such as dynorphin A and one of several types of opioid receptors. They can variably produce hallucinogenic effects, pro-depressive and dysphoric effects, sedation, analgesic effects, antipruritic (anti-itch) effects, and anti-addictive effects, among others. Due to their various effects, KOR agonists are used for a variety of medical uses and for other purposes. Salvinorin A is a highly potent and selective KOR agonist and hallucinogen found in Salvia divinorum (diviner's sage) which has been used as an entheogen by the Mazatec people of Mexico and as a recreational drug elsewhere. The psychoactive and other effects of salvinorin A have been evaluated in clinical studies. The non-selective opioid receptor antagonist naltrexone blocks the effects of salvinorin A. Synthetic analogues with greater potency and/or duration include salvinorin B methoxymethyl ether (2-MMSB) and salvinorin B ethoxymethyl ether (2-EMSB). The irreversible G protein-biased agonist RB-64 (22-thiocyanatosalvinorin A) has unknown psychoactivity. Nalorphine (N-allylnormorphine; Lethidrone; Nalline) was an early opioid antagonist used to reverse opioid overdose which acts as a dual μ-opioid receptor (MOR) agonist–antagonist and KOR agonist and was superseded by other drugs like naloxone due to producing dysphoria and hallucinogenic effects among other drawbacks.
== Medical uses == Varicella vaccine is 70% to 90% effective for preventing varicella and more than 95% effective for preventing severe varicella. Follow-up evaluations have taken place in the United States of children immunized that revealed protection for at least 11 years. Studies were conducted in Japan which indicated protection for at least 20 years. People who do not develop enough protection when they get the vaccine may develop a mild case of the disease when in close contact with a person with chickenpox. In these cases, people show very little sign of illness. This has been the case of children who get the vaccine in their early childhood and later have contact with children with chickenpox. Some of these children may develop mild chickenpox also known as breakthrough disease. Another vaccine, known as zoster vaccine, is simply a larger-than-normal dose of the same vaccine used against chickenpox and is used in older adults to reduce the risk of shingles (also called herpes zoster) and postherpetic neuralgia, which are caused by the same virus. The recombinant zoster (shingles) vaccine is recommended for adults aged 50 years and older.
Sources: en.wikipedia.org
=== School psychology === School psychologists are primarily concerned with the academic, social, and emotional well-being of children and adolescents within a scholastic environment. In the UK, they are known as "educational psychologists". Like clinical (and counseling) psychologists, school psychologists with doctoral degrees are eligible for licensure as health service psychologists, and many work in private practice. Unlike clinical psychologists, they receive much more training in education, child development and behavior, and the psychology of learning. Common degrees include the Educational Specialist Degree (EdS), Doctor of Philosophy (PhD), and Doctor of Education (EdD). Traditional job roles for school psychologists employed in school settings have focused mainly on assessment of students to determine their eligibility for special education services in schools, and on consultation with teachers and other school professionals to design and carry out interventions on behalf of students. Other major roles also include offering individual and group therapy with children and their families, designing prevention programs (e.g. for reducing dropout), evaluating school programs, and working with teachers and administrators to help maximize teaching efficacy, both in the classroom and systemically.
=== Lego peptides / Ionic self-complementary peptides === These peptides are approximately 5 nm in size and have 16 amino acids. The class of Lego peptides has the unique characteristics of having two distinct surfaces being either hydrophobic or hydrophilic, similar to the pegs and holes of Lego blocks. The hydrophobic side promotes self-assembly in water and the hydrophilic side has a regular arrangement of charged amino-acid residues, which in turn brings about a defined pattern of ionic bonds. The arrangement of the residues can be classified according to the order of the charges; Modulus I has a charge pattern of + − + − + −, modulus II + + − − + + − −, and modulus III + + + − − − + + +, and so on. The peptides self-assemble into nanofibers approximately 10 nm long in the presence of alkaline cations or an addition of peptide solution. The fibers form ionic interactions with each other to form checkerboard-like matrices, which develop into a scaffold hydrogel with a high water content of larger than 99.5–99.9% and pores of 10–200 nm in diameter. These hydrogels allow neurite outgrowth and therefore can be used as scaffolds for tissue engineering.
=== Silicone gel sheeting === Silicone gel sheeting is sometimes used to treat hypertrophic scars. Silicone gel sheets may improve the appearance of scars slightly compared with applying onion extract and may reduce pain compared with no treatment with silicone gel sheets or pressure garments. It is uncertain whether silicone gel sheets are more effective than other treatment methods.
Sources: en.wikipedia.org
Major regulatory agencies have not approved it for any indication. Some countries permit it only under prescription frameworks, while others classify it as a controlled substance.
Much of the evidence comes from case reports and accounts of unregulated use rather than controlled trials. Differences in product purity and dosing add further variability.
Laboratory work focuses on receptor binding and cellular signalling. Observational reports document outcomes after use, and analytical chemists examine samples to assess content and purity.
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.