melanocortin comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2026-03-24. Numbers and descriptions here follow the published literature rather than marketing material.
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.
The peer-reviewed record is dominated by small early-phase studies, case reports and pharmacovigilance summaries rather than large randomised trials. Papers typically examine tanning response, receptor selectivity or patterns of reported adverse events. Many note that participants obtained the peptide outside a clinical setting, which limits verification of composition and administered amount. Reported events vary widely, and causality is frequently unclear because the identity and purity of self-sourced material are unknown. Open questions include whether repeated melanocortin receptor stimulation produces cumulative effects, and how often label claims match actual content.
Identification in laboratories relies on reversed-phase liquid chromatography coupled with tandem mass spectrometry, with product-ion spectra compared against a certified reference standard. High-resolution mass spectrometry supplies accurate mass confirmation, and peptide mapping after enzymatic digestion separates melanotan II from closely related analogues. Quantitation of seized material is complicated by unknown counter-ions and residual trifluoroacetate left from purification. Immunoassays raised against alpha-melanocyte-stimulating hormone can cross-react, so chromatographic confirmation is normally required. Urinary detection windows are short, and reported limits of detection differ substantially between laboratories.
Melanotan II holds no marketing authorisation from the Food and Drug Administration, the European Medicines Agency, the UK Medicines and Healthcare products Regulatory Agency or Australia's Therapeutic Goods Administration. Products sold under that name are treated as unapproved new drugs, and their sale or import is prohibited in several jurisdictions. Other countries classify the peptide as a prescription-only medicine or place it among controlled substances, so the legal position changes with the destination market. No pharmacopoeial monograph supplies an official specification, because the material is not a licensed pharmaceutical. Consequently, products offered online are not manufactured to a shared public standard.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic cyclic heptapeptide | Analog of alpha-MSH with an internal lactam bridge |
| Molecular weight | Approximately 1024 daltons | Free base value; salt forms differ |
| Appearance | White to off-white powder | Usually supplied as a lyophilized solid |
| Solubility | Freely soluble in water | Poorly soluble in nonpolar solvents |
| Typical storage | −20 °C, dry, protected from light | Repeated freeze-thaw cycles degrade peptides |
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
Melanotan II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
Receptor-binding studies classify melanotan II as a non-selective melanocortin agonist. It interacts with MC1R, MC3R, MC4R and MC5R, with reported affinities in the low nanomolar range and no strong subtype preference. Activation of MC1R on dermal melanocytes shifts pigment synthesis toward eumelanin, the dark polymer deposited in melanosomes and transferred to keratinocytes. Because the same peptide engages MC4R in the hypothalamus, it also appears in animal work on food intake and erectile response, which is why it is discussed in both pigment and metabolic research. Which receptor populations dominate after systemic exposure in humans is not fully established.
Verification of a purchased sample requires documentation linking a batch to a certificate of analysis, and that document should be read for the methods used rather than the headline purity figure. A single chromatographic percentage does not establish identity. Independent laboratories can perform identity and content assays, but no such test establishes that a product is suitable for human use. Claims about efficacy rest largely on small, early studies rather than on replicated controlled trials, and that gap remains open.
Identity testing for a cyclic peptide of this size usually relies on reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The mass spectrum confirms molecular weight, while the chromatographic trace indicates the proportion of related impurities. Tandem mass spectrometry can provide sequence-level information when fragmentation data are compared against a reference standard. Nuclear magnetic resonance is sometimes used to confirm the lactam bridge, although it requires more material and greater operator expertise than routine chromatographic methods.
=== 2000–2010: Further expansion === In 2001, Henry McKinnell became CEO, replacing William C. Steere, Jr. In 2002, The Bill & Melinda Gates Foundation purchased stock in Pfizer. In 2004, the company received approval for Lyrica (pregabalin), an anticonvulsant and anxiolytic medication used to treat epilepsy, neuropathic pain, fibromyalgia, restless leg syndrome, and generalized anxiety disorder. The United States patent on Lyrica was challenged by generic manufacturers and was upheld in 2014, extending the expiration date to 2018. In July 2006, Jeff Kindler was named CEO, replacing Henry McKinnell. On December 3, 2006, Pfizer ceased development of torcetrapib, a drug that increases production of HDL, which reduces LDL thought to be correlated to heart disease. During a Phase III clinical trial involving 15,000 patients, more deaths than expected occurred in the group that took the medicine, and the mortality rate of patients taking the combination of torcetrapib and Lipitor (82 deaths during the study) was 60% higher than those taking Lipitor alone (52 deaths during the study). Lipitor alone was not implicated in the results, but Pfizer lost nearly $1 billion developing the failed drug and its stock price dropped 11% on the day of the announcement. Between 2007 and 2010, Pfizer spent $3.3 million on investigations and legal fees and recovered about $5.1 million, and had another $5 million of pending recoveries from civil lawsuits against makers of counterfeit prescription drugs.
Ractopamine () is an animal feed additive used to promote leanness and increase food conversion efficiency in farmed animals in few countries, banned in most. Pharmacologically, it is a phenol-based TAAR1 agonist and β adrenoreceptor agonist that stimulates β1 and β2 adrenergic receptors. It is most commonly administered to animals for meat production as ractopamine hydrochloride. It is the active ingredient in products marketed in the US as Paylean for swine, Optaflexx for cattle, and Topmax for turkeys. It was developed by Elanco Animal Health, a former division of Eli Lilly and Company. As of 2025, the use of ractopamine "is banned or its use restricted in 168 nations", including the European Union, China and Russia, while it is legal in some other countries, with differing maximum residual limits (MRLs) in meat. Examples include the United States (50 ppb in pork, 30 ppb in beef); Japan, Taiwan and South Korea (10 ppb, in accordance with the Codex Alimentarius Commission); and New Zealand (0.1 ppb). Commercial ractopamine is a mixture of all four possible stereoisomers. It is also a positional isomer of dobutamine, a related drug.
Kyiv came under air attack in the early hours of the morning. Vitali Klitschko, Kyiv's Mayor, said that debris from intercepted missiles struck the city zoo in the Solomianskyi District and the Shevchenkivskyi District, as well as several cars, and wounded three people. According to Kyiv's military administrator, Serhiy Popko, the attack was "exceptional", as it involved "the maximum number of attack missiles in the shortest period of time." Ukraine stated all eighteen missiles were shot down, including six Kh-47M2 Kinzhal missiles. The attacks came from the north, south and east while being launched from air, land and sea, according to Ukrainian military commander Valerii Zaluzhny. However, Russian Defence Minister Sergei Shoigu dismissed the Ukrainian claims, saying that they had launched a lesser amount of missiles. The Russian Ministry of Defence claimed to have destroyed a US-built Patriot surface-to-air missile defense system with a Kinzhal missile. A US official later told CNN that a Patriot system was likely damaged but not destroyed during the attack, and that assessments for potential damage were ongoing. According to a US official the Patriot system could be repaired in Ukraine. Due to modular nature of the system it may just require the replacement of a damaged component with a new one. Denis Pushilin, head of the Russian-backed Donetsk People's Republic, said that Russian forces had seized several Ukrainian positions near Avdiivka.
Two different Dromaius species were present in Australia at the time of European settlement, and one additional species is known from fossil remains. The insular dwarf emus, D. n. baudinianus and D. n. minor, originally present on Kangaroo Island and King Island respectively, both became extinct shortly after the arrival of Europeans. D. n. diemenensis, another insular dwarf emu from Tasmania, became extinct around 1865. The mainland subspecies, D. n. novaehollandiae, remains common. The population of these birds varies from decade to decade, largely being dependent on rainfall; in 2009, it was estimated that there were between 630,000 and 725,000 birds. Emus were introduced to Maria Island off Tasmania, and Kangaroo Island off the coast of South Australia, during the 20th century. The Maria Island population died out in the mid-1990s. The Kangaroo Island birds have successfully established a breeding population. In 1912, the Australian ornithologist Gregory M. Mathews recognised three living subspecies of emu, D. n. novaehollandiae (Latham, 1790), D. n. woodwardi Mathews, 1912 and D. n. rothschildi Mathews, 1912. The Handbook of the Birds of the World, however, argues that the last two of these subspecies are invalid; natural variations in plumage colour and the nomadic nature of the species make it likely that there is a single race in mainland Australia. Examination of the DNA of the King Island emu shows this bird to be closely related to the mainland emu and hence best treated as a subspecies.
Sources: en.wikipedia.org
Native to cold temperate coastal areas of Japan, Korea, China, and Russia, in recent decades it has become established in temperate regions around the world, including New Zealand, the United States, Belgium, France, Great Britain, Spain, Italy, Argentina, Australia and Mexico. It was nominated one of the 100 worst invasive species in the world. Undaria is commonly initially introduced or recorded on artificial structures, where its r-selected growth strategy facilitates proliferation and spread to natural reef sites. Undaria populations make a significant but inconsistent contribution of food and habitat to intertidal and subtidal reefs. Undaria invasion can cause changes to native community composition at all trophic levels. As well as increasing primary productivity, it can reduce the abundance and diversity of understory algal assemblages, out-compete some native macroalgal species and affect the abundance and composition of associated epibionts and macrofauna, including gastropods, crabs, urchins and fish. Its dense congregation and capability to latch onto any hard surface has caused it to become a major cause of damage to aquaculture apparatus, decreasing efficiency of fishing industries by clogging underwater equipment and fouling boat hulls. Eradication of wakame within a localized area usually involves getting rid of the algae underwater, often via regular inspection of aquatic environments.
== Notable people == Jacob M. Gile (1849–1937), architect in Colorado, born in Lebanon Doug Jones, MLB All-Star relief pitcher Mel Kenyon, Hall of Fame midget car driver; had four top-five finishes in Indianapolis 500 Sylvia Likens, murder victim, born in Lebanon, murdered in Indianapolis in 1965 when she was 16 Ray Long, editor of Cosmopolitan from 1919 to 1931, born in Lebanon Ami McKay, novelist, playwright and journalist Rick Mount, 1966 Indiana "Mr. Basketball" award recipient, 3x All-American Purdue player William Perigo, basketball head coach at Western Michigan University and University of Michigan Drew Powell, actor, is best known for his role as Hoss Cartwright on the TV series Ponderosa Allen Saunders, cartoonist and writer, Mary Worth G. Thomas Tanselle, textual critic, bibliographer, and book collector, especially known for his work on Herman Melville Craig Terrill, former Purdue and Seattle Seahawks football player Herman B Wells, former President of Indiana University, attended Lebanon High School
In 2005–06, fragrance mix was the third-most-prevalent allergen in USA patch tests (11.5%). 'Fragrance' was voted Allergen of the Year in 2007 by the American Contact Dermatitis Society. An academic study in the United States published in 2016 has shown that "34.7 % of the population reported health problems, such as migraine headaches and respiratory difficulties, when exposed to fragranced products". The composition of fragrances is usually not disclosed in the label of the products, hiding the actual chemicals of the formula, which raises concerns among some consumers. In the United States, this is because the law regulating cosmetics protects trade secrets. In the United States, fragrances are regulated by the Food and Drug Administration if present in cosmetics or drugs, by the Consumer Product Safety Commission if present in consumer products. No pre-market approval is required, except for drugs. Fragrances are also generally regulated by the Toxic Substances Control Act of 1976 that "grandfathered" existing chemicals without further review or testing and put the burden of proof that a new substance is not safe on the EPA. The EPA, however, does not conduct independent safety testing but relies on data provided by the manufacturer. A 2019 study of the top-selling skin moisturizers found 45% of those marketed as "fragrance-free" contained fragrance. Cosmetics are regulated in the United Kingdom and the composition of products must be provided.
Riders are recruited by Spider-Man into the initiative to stop his malfunctioning Spider-Bots. Web Slingers was directed by Spider-Man director Jon Watts along with Brett Strong, and was written by Steven Spiegel and featured visual effects by Framestore. A one-act version of Rogers: The Musical premiered at the Hyperion Theater on June 30, 2023, and ran for a limited time until August 31. Two new attractions, Avengers Infinity Defense and Stark Flight Lab, feature Downey reprising his role as Tony Stark along with additional returning MCU actors. Both rides are expected to open in 2028.
== Construction of expression plasmids == A number of engineered genetic sequences must be incorporated into the host cell to perform two-hybrid analysis or one of its derivative techniques. The considerations and methods used in the construction and delivery of these sequences differ according to the needs of the assay and the organism chosen as the experimental background. There are two broad categories of hybrid library: random libraries and cDNA-based libraries. A cDNA library is constituted by the cDNA produced through reverse transcription of mRNA collected from specific cells of types of cell. This library can be ligated into a construct so that it is attached to the BD or AD being used in the assay. A random library uses lengths of DNA of random sequence in place of these cDNA sections. A number of methods exist for the production of these random sequences, including cassette mutagenesis. Regardless of the source of the DNA library, it is ligated into the appropriate place in the relevant plasmid/phagemid using the appropriate restriction endonucleases.
Sources: en.wikipedia.org
The renin–angiotensin–aldosterone system is a major blood pressure regulating mechanism. Markers of electrolyte and water imbalance in the body such as hypotension, low distal tubule sodium concentration, decreased blood volume and high sympathetic tone trigger the release of the enzyme renin from the cells of juxtaglomerular apparatus in the kidney. Renin activates a circulating liver derived prohormone angiotensinogen by proteolytic cleavage of all but its first ten amino acid residues known as angiotensin I. ACE (angiotensin converting enzyme) then removes a further two residues, converting angiotensin I into angiotensin II. ACE is found in the pulmonary circulation and in the endothelium of many blood vessels. The system increases blood pressure by increasing the amount of salt and water the body retains. Angiotensin II is also a potent vasoconstrictor.
Several phase 1 clinical trials have been performed by experts in the field of adoptive immunotherapy of cancer. Hans Klingemann and Sally Arai completed a US trial at Rush University Medical Center (Chicago) in renal cell cancer and melanoma patients in 2008, and Torsten Tonn, MD and Oliver Ottmann, MD completed the European trial at the University of Frankfurt in patients with various solid and hematological malignancies in 2013. Armand Keating at Princess Margaret Hospital in Toronto conducted a trial in which NK-92 cells were given to patients who had relapsed after autologous bone marrow transplants for leukemia or lymphoma. In all clinical trials so far, NK-92 cells were administered as a simple intravenous infusion, dosed two or three times per treatment course, and given in the outpatient setting. Of the 39 patients enrolled across the three studies, 2 serious (grade 3–4) side-effects occurred during or after the infusion of NK-92 cells, the side effects disappeared afterward. The doses given to patients ranged from 1 × 108 cells/m2 to 1 × 1010 cells/m2 per infusion. Patients received between two and three infusions over a period of less than a week. About one-third of the treated patients had clinically meaningful responses with some of them fully recovering.
The image above shows the interpretation of an antibody panel used in serology to detect antibodies towards the most relevant blood group antigens. Each row represents "reference" or "control" red blood cells of donors which have known antigen compositions and are ABO group O. The + symbol means that the antigen is present on the reference red blood cells, and 0 means it is absent; nt means "not tested". The "result" column to the right displays reactivity when mixing reference red blood cells with plasma from the patient in 3 different phases: room temperature, 37 °C and AHG (with anti-human globulin, by the indirect antiglobulin test).
Symptoms of ethanol overdose may include nausea, vomiting, CNS depression, coma, acute respiratory failure, or death. Levels of even less than 0.1% can cause intoxication, with unconsciousness often occurring at 0.3–0.4%. Death from ethanol consumption is possible when blood alcohol levels reach 0.4%. A blood level of 0.5% or more is commonly fatal. The oral median lethal dose (LD50) of ethanol in rats is 5,628 mg/kg. Directly translated to human beings, this would mean that if a person who weighs 70 kg (150 lb) drank a 500 mL (17 US fl oz) glass of pure ethanol, they would have an estimated 50% risk of dying. The highest blood alcohol level ever recorded, in which the subject survived, is 1.41%.
It is also used off-label in the management of moderate to severe cases of serotonin syndrome, a complex of symptoms associated with the use of serotonergic drugs, such as selective serotonin reuptake inhibitors (and monoamine oxidase inhibitors), and in cases of high levels of serotonin in the blood resulting from a serotonin-producing carcinoid tumor. There is uncertainty about the proper dose of cyproheptadine for treatment of serotonin syndrome, with doses of 4 to 16 mg having been employed but doses of 20 to 30 mg possibly actually being necessary based on positron emission tomography (PET) imaging research. Cyproheptadine has sedative effects and can be used to treat insomnia similarly to other centrally-acting antihistamines. The recommended dose for this use is 4 to 8 mg.
Sources: en.wikipedia.org
It is a synthetic seven-amino-acid peptide modeled on alpha-melanocyte-stimulating hormone. It carries two non-natural substitutions and a cyclic bridge that increase its stability relative to the natural hormone. It circulates as a research chemical and is not an approved medicine.
Melanotan-1, also called afamelanotide, is a shorter linear analog with a different amino acid sequence and no lactam ring. It has been evaluated in formal clinical programs, while melanotan-2 has not. The two are distinct molecules and are not interchangeable.
No. Bremelanotide is a related but distinct cyclic peptide that reached approved status for one specific clinical indication. Melanotan-2 is a separate molecule with its own sequence and properties. Shared ancestry in the melanocortin family does not make them the same substance.
Regulatory treatment varies by country. In the United States, the European Union and Australia it is an unapproved drug and its sale is restricted, while some other jurisdictions list it as prescription-only or controlled. The applicable rules depend on the country of import.