The short version of research chemical fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-09-20 and is reviewed periodically as new material appears.
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.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | -20 °C or below | For the lyophilised powder, desiccated |
| Storage form | Sealed vial, protected from light | Amber glass or foil-wrapped containers |
| Reconstituted stability | Short, refrigerate | Degradation accelerates in solution |
| Typical analytical method | Reversed-phase HPLC with mass spectrometry | Purity assessment plus identity confirmation |
| Common synonyms | Melanotan II, MT-II | Also written melanotan-2 |
Regulatory treatment varies by country. In the United States the peptide is not approved as a medicine, and products offered for human use may be treated as unapproved new drugs; some states also restrict sale. Australia, the United Kingdom, and European Union member states apply comparable restrictions to unapproved peptide products. Border agencies have seized shipments labelled as research chemicals. Classification may change over time, and the legal position for personal importation is not clearly settled in most published guidance.
Lyophilised melanotan-2 is supplied as a solid, which is more stable than a solution. The material is hygroscopic, so weighing is done quickly, in low humidity, with the container kept sealed. Reconstitution usually uses water for injection or bacteriostatic water, added down the wall of the vial to limit foaming. A reconstituted solution is held at 2 to 8 °C and kept away from light. Repeated freezing and thawing of the same vial is avoided because ice crystal formation and concentration effects degrade the peptide.
Reversed-phase high-performance liquid chromatography is the routine method for purity assessment. Peptides absorb near 214 nm because of the peptide bond, and a gradient of acetonitrile in water separates the intact peptide from deletion sequences, oxidised products, and earlier-eluting fragments at neutral pH. Electrospray ionisation mass spectrometry provides an orthogonal check: the measured mass must agree with the theoretical value. Amino acid analysis and peptide mapping confirm structure but are used less often. Reference standards remain scarce because the peptide is not described in any pharmacopoeia.
Published human data come mostly from small, short studies rather than large controlled trials. Reported outcomes include increased skin pigmentation and, in some reports, effects on appetite and libido, but sample sizes are small and follow-up is limited. Whether long-term use produces durable pigment changes or adverse effects is not established. Because products sold outside pharmacies are not standardized, the actual content of any given vial is often unknown. Independent testing of such material is uncommon.
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.
Published research on the compound remains limited. Much of the human data comes from small, early-stage studies rather than large controlled trials, and several questions about effects and variability between individuals remain open. Investigators have examined receptor activity, pigment pathways, and related physiological responses in laboratory and animal models. Findings from those models do not automatically translate to human outcomes. Reviews frequently note the scarcity of rigorous clinical evidence and call for better-characterized study material.
Because the substance circulates mainly through informal markets, verification is a recurring theme in technical discussion. Independent analyses have found that labeled content and actual content can diverge, and that purity varies between samples. Analytical laboratories use reversed-phase chromatography to separate components and mass spectrometry to confirm identity. Isotope-labeled internal standards improve quantification in complex matrices. Such methods describe what a sample contains but say nothing about its sterility, lawful status, or suitability for any use. Open questions remain about how consistently testing is applied across the supply chain.
Regulatory treatment of this peptide varies by country. It holds no marketing authorization as a medicine in the United States, the European Union, or most other jurisdictions. Some countries classify products containing it as prescription-only or unlicensed medicines, which restricts lawful supply. Authorities have issued public notices warning that unregulated products may contain undeclared or incorrect ingredients. The molecule also appears on prohibited lists for competitive sport. These measures address supply oversight rather than any approved therapeutic role.
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.
=== U.S. response on humanitarian aid === In May 2026, U.S. Secretary of State Marco Rubio said the United States had offered $100 million in humanitarian aid to Cuba, including food and medical supplies. He criticized the Cuban government, saying it was preventing humanitarian aid from reaching the population. The statement was made in the context of long-standing U.S. sanctions and trade restrictions on Cuba, which have restricted economic and humanitarian flows to the country. Rubio also described the situation in Cuba as "unacceptable" and called for major changes in the country's governance.
== Medical applications == Vitamin E has been suggested as a supplement for helping many health conditions, mostly due to its antioxidant activity and potential to protect cells from oxidative damage. In the US, the vitamin is widely available as an over-the-counter supplement; however, medical evidence supporting its effectiveness and safety for treating or preventing a variety of health conditions is mixed. Vitamin E can also interact with some medications and other supplements. Vitamin E has been studied as a treatment for skin health and skin ageing, immune function, and managing conditions like cardiovascular disease or Alzheimer's disease (AD), or certain types of cancer. Most studies have found limited or inconclusive benefits and the potential for some risks. It is most often recommended to obtain vitamin E through a balanced diet because high-dose supplementation may have health risks. There is evidence that the sale of dietary supplement vitamin E has decreased by up to 33% following a report showing little or no effect of vitamin E in preventing cancer or cardiovascular disease. In 2023, it was the 290th most commonly prescribed medication in the United States, with more than 500,000 prescriptions.
== Taxonomy == The American kestrel was formally described in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae under the current binomial name Falco sparverius. Linnaeus based his account on the "little hawk" that had been described and illustrated by the English naturalist Mark Catesby in his book The Natural History of Carolina, Florida and the Bahama Islands that was published between 1729 and 1732. Linnaeus specified the type locality as America but this was restricted to South Carolina based on Catesby. Based on appearance and behavior it was for many years considered a member of the primarily European and African kestrel clade within the genus Falco, but DNA analysis shows the American kestrel is instead genetically more closely related to all other falcons, placed basal to all of the "non-kestrel" falcons. Though the species is thus not actually a kestrel in the phylogenetic sense, it has not been renamed as a result of these genetic analyses. A process of convergent evolution to fit a similar ecosystem niche, hunting small, largely ground-dwelling, prey in the same manner as the true kestrels, have left it with similar physical characteristics and hunting methods. The entire genus are all so closely related that most or all can be hybridized by artificial insemination.
3D Realms was eventually acquired in part by Interceptor Entertainment, and in 2014, Interceptor announced plans to make a new Duke Nukem game, Duke Nukem: Mass Destruction. Gearbox filed suit against 3D Realms and Interceptor based on the fact that Gearbox now owned the rights to the Duke Nukem franchise. The case was settled out of court in August 2015, with 3D Realms and Interceptor acknowledging that Gearbox has full rights to the Duke Nukem series. Following the settlement, Gearbox released Duke Nukem 3D: 20th Anniversary Edition World Tour in September 2016. The game included new levels developed in conjunction with some of the original developers, re-recorded lines by original Duke voice actor Jon St. John, and new music from original composer Lee Jackson. It was released on October 11, 2016.
Hematologic diseases in which it is positive include ALL, angioimmunoblastic T cell lymphoma, Burkitt lymphoma, chronic myelogenous leukemia in blast crisis (90%), diffuse large B-cell lymphoma (variable), follicular center cells (70%), hairy cell leukemia (10%), and myeloma (some). It tends to be negative in acute myeloid leukemia, chronic lymphocytic leukemia, mantle cell lymphoma, and marginal zone lymphoma. CD10 is found on non-T ALL cells, which derive from pre-B lymphocytes, and in germinal center-related non-Hodgkin lymphoma such as Burkitt lymphoma and follicular lymphoma, but not on leukemia cells or lymphomas, which originate in more mature B cells.
Sources: en.wikipedia.org
==== Dissolution and reestablishment ==== On August 9, 2017, President Rodrigo Duterte signed Executive Order No. 38, revoking the Executive Order No. 183 signed by (former) President Benigno Aquino III on May 29 of 2015, due to the reason of the lack of funds to fully establish the NIR according to Benjamin Diokno, the Secretary of Budget and Management. Its dissolution upset the NIR regional officials and provoked strong negative reactions from the Negrenses. On June 13, 2024, Negros island together with neighboring Siquijor were grouped together under the reestablished Negros Island Region with the signing of Republic Act No. 12000 by President Bongbong Marcos.
Like gars, bowfin are bimodal breathers—they have the capacity to breathe both water and air. Their gills exchange gases in the water, allowing them to breathe, but they also have a gas bladder that serves to maintain buoyancy and also allows them to breathe air by means of a small pneumatic duct connected from the foregut to the gas bladder. They can break the surface to gulp air, which allows them to survive conditions of aquatic hypoxia that would be lethal to most other species. The bowfin is long-lived, with ages up to 33 years reported.
bacterial and mitochondrial N-formyl peptides and thereby initiates innate host immune responses. various synthetic N-formyl and non-formylated peptides that show distinguishing differences from those that interact with FPR2 and FPR3. T20/DP178 & T21/DP107, N-acetylated polypeptides derived from the gp41 HIV-1 envelope protein. This interaction is of unknown physiological significance although peptide T20/DP178 is a licensed anti-retrovirus agent (pentafuside) termed Enfuvirtide which acts at the level of HIV-target cell fusion and is used clinically to treat HIV-1 infection). Annexin A1 (also termed ANXA1 and lipocortin 1) and its N-terminal peptides (Ac2–26 and Ac9–25). At low concentrations, these agents stimulate neutrophils to raise cytosolic Ca2+ levels and thereby activate Ca2+-dependent signaling pathways; however, they do not fully activate the MAPK pathway but rather leave the neutrophil desensitized (i.e. unresponsive) to chemokine IL-8. At high concentrations, in contrast, the agents fully activate neutrophils and are potent pro-inflammatory stimulants.
Circumduction is a conical movement of a body part, such as a ball and socket joint or the eye. Circumduction is a combination of flexion, extension, adduction and abduction. Circumduction may be performed at ball and socket joints, such as the hip and shoulder, as well as other parts of the body such as fingers, hands, feet, and head. For example, circumduction occurs when spinning the arm when performing a serve in tennis or bowling a cricket ball.
The males of ancient Greece believed that small penises were ideal. Scholars believe that most ancient Greeks probably had the same size penises as other Europeans, but Greek artistic portrayals of handsome youths show them with inordinately small, uncircumcised penises with disproportionately large foreskins, indicating that these were seen as ideal. Large penises in Greek art are reserved for comically grotesque figures, such as satyrs, a class of hideous, horse-like woodland spirits, who are shown in Greek art with absurdly massive penises. Actors portraying male characters in ancient Greek comedy wore enormous, fake, red penises, which dangled underneath their costumes; these were intended as ridiculous and were meant to be laughed at. In Aristophanes's comedy The Clouds, "Mr. Good Reason" gives the character Pheidippides a description of the ideal youth: "A glistening chest and glowing skin / Broad shoulders, a small tongue /A mighty bottom and a tiny prong." In Greek mythology, Priapus, the god of fertility, had an impossibly large penis that was permanently erect. Priapus was widely seen as hideous and unattractive. A scholion on Apollonius of Rhodes's Argonautica states that when Priapus' mother Aphrodite, the goddess of love and beauty, gave birth to him, she was so horrified by the size of his penis, his massive potbelly, and his huge tongue that she abandoned him to die in the wilderness. A herdsman found him and raised him as his son, later discovering that Priapus could use his massive penis to aid in the growth of plants.
Sources: en.wikipedia.org
== Society and culture == Gynecomastia can result in psychological distress for those with the condition. Support groups exist to help improve the self-esteem of affected people. Moob, a portmanteau of man and boob, is a popular term to refer to male breasts. Use of anabolic steroids can result in gynecomastia, and male breasts are sometimes referred to using the pejorative bitch tits in bodybuilding communities. In Murray v. Janssen Pharmaceuticals, Murray was a Risperidone user who was prescribed the medication at age nine and developed male breasts. A jury decided in Murray's favor in November 2015 and awarded him $1.75 million. The $1.75 million jury verdict represented damages for "disfigurement and mental anguish", though it was later reduced to $680,000. In the second portion of the bifurcated trial, the plaintiffs sought to prove that the companies knew and deliberately disregarded evidence that Risperidone could lead to gynecomastia in young males, and nonetheless promoted the medication off-label and released the medication into the open market for prescription and use by patients without disclosing the side effects. The jury found for the plaintiffs in the second portion of the trial and awarded $8 billion in punitive damages. The amount was later reduced to $6.8 million by Judge Kenneth Powell Jr. In 2019, a 12-person Philadelphia jury awarded $8 billion in punitive damages to plaintiffs tied to the use of risperidone. Risperidone is an atypical antipsychotic that was originally approved to treat psychosis.
Stratum basale (basal layer) Stratum spinosum (prickle layer) Stratum granulosum (granular layer) Stratum corneum (keratinized layer) In nonkeratinised epithelium, the two deep layers (basale and spinosum) remain the same but the outer layers are termed the intermediate and superficial layers. Depending on the region of the mouth, the epithelium may be nonkeratinized or keratinized. Nonkeratinized squamous epithelium covers the soft palate, inner lips, inner cheeks, the floor of the mouth, and ventral surface of the tongue. Keratinized squamous epithelium is present in the gingiva and hard palate as well as areas of the dorsal surface of the tongue. Keratinization is the differentiation of keratinocytes in the stratum granulosum into nonvital surface cells or squames to form the stratum corneum. The cells terminally differentiate as they migrate to the surface from the stratum basale where the progenitor cells are located to the superficial surface. Unlike keratinized epithelium, nonkeratinized epithelium normally has no superficial layers showing keratinization. Nonkeratinized epithelium may, however, readily transform into a keratinizing type in response to frictional or chemical trauma, in which case it undergoes hyperkeratinization. This change to hyperkeratinization commonly occurs on the usually nonkeratinized buccal mucosa when the linea alba forms, a white ridge of calloused tissue that extends horizontally at the level where the maxillary and mandibular teeth come together and occlude.
[A] is the concentration of reagent A, etc. It is possible in principle to obtain values of the activity coefficients, γ. For solutions, equations such as the Debye–Hückel equation or extensions such as Davies equation Specific ion interaction theory or Pitzer equations may be used. However this is not always possible. It is common practice to assume that Γ is a constant, and to use the concentration quotient in place of the thermodynamic equilibrium constant. It is also general practice to use the term equilibrium constant instead of the more accurate concentration quotient. This practice will be followed here. For reactions in the gas phase partial pressure is used in place of concentration and fugacity coefficient in place of activity coefficient. In the real world, for example, when making ammonia in industry, fugacity coefficients must be taken into account. Fugacity, f, is the product of partial pressure and fugacity coefficient. The chemical potential of a species in the real gas phase is given by
21 July to 21 September Operation Strangle was conducted by the U.S. 1st Infantry Division and the ARVN 8th Regiment, 5th Division in Bình Dương Province. The operation resulted in 365 PAVN/VC killed and 35 captured.
Newborn screening (NBS) is a public health program of screening in infants shortly after birth for conditions that are treatable, but not clinically evident in the newborn period. The goal is to identify infants at risk for these conditions early enough to confirm the diagnosis and provide intervention that will alter the clinical course of the disease and prevent or ameliorate the clinical manifestations. NBS started with the discovery that the amino acid disorder phenylketonuria (PKU) could be treated by dietary adjustment, and that early intervention was required for the best outcome. Infants with PKU appear normal at birth, but are unable to metabolize the essential amino acid phenylalanine, resulting in irreversible intellectual disability. In the 1960s, Robert Guthrie developed a simple method using a bacterial inhibition assay that could detect high levels of phenylalanine in blood shortly after a baby was born. Guthrie also pioneered the collection of blood on filter paper which could be easily transported, recognizing the need for a simple system if the screening was going to be done on a large scale. Newborn screening around the world is still done using similar filter paper. NBS was first introduced as a public health program in the United States in the early 1960s, and has expanded to countries around the world. Screening programs are often run by state or national governing bodies with the goal of screening all infants born in the jurisdiction for a defined panel of treatable disorders.
Sources: en.wikipedia.org
The lyophilised solid is best kept cold, dry and dark, typically at minus twenty degrees Celsius. Moisture and repeated warming cycles are the main causes of degradation. Solutions prepared from the powder are less stable and are normally used quickly.
Reversed-phase liquid chromatography assesses purity, while mass spectrometry confirms molecular mass and detects sequence errors. Amino acid analysis and peptide mapping add structural detail. These techniques are complementary rather than interchangeable.
It is listed as a prohibited peptide hormone by the World Anti-Doping Agency. No medicines regulator has approved it for human use. Import and sale rules vary by country.
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.