melanotan-2 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.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Reported observations after unregulated use include shifts in skin pigmentation and, in some accounts, unintended changes to moles and other lesions. Whether these outcomes are causally linked to the compound, and how often they occur, remain open questions because controlled data are scarce. The absence of standardised dosing and verified product purity complicates interpretation. Researchers have called for better surveillance and analytical characterisation of samples obtained outside regulated channels. Conclusions drawn from anecdotal evidence should be treated as provisional.
| 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 |
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.
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-2 is handled in the laboratory as a lyophilised powder that dissolves readily in water, dimethyl sulfoxide and dimethylformamide, with limited solubility in ethanol. Stock solutions prepared in an organic solvent often precipitate when diluted into aqueous buffer, so gradual dilution with mixing is standard practice. The peptide carries a tryptophan residue and a histidine residue, both sensitive to oxidation and to alkaline conditions. Working solutions are therefore kept near neutral to slightly acidic pH, protected from light, and consumed within the same working session whenever that is practical.
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.
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.
=== Labeling and advertising === Studies conducted by the US Food and Drug Administration (FDA) from 2014 through 2019, determined that a majority of CBD products are not accurately labeled with the amount of CBD they contain. For example, a 2017 analysis of cannabidiol content in oil, tincture, or liquid vape products purchased online in the United States showed that 69% were mislabeled, with 43% having higher and 26% having lower content than stated on product labels. In 2020, the FDA conducted a study of 147 CBD products and found that half contained THC. From 2015 through 2022, the FDA issued dozens of warning letters to American manufacturers of CBD products for false advertising and illegal interstate marketing of CBD as an unapproved drug to treat diseases, such as cancer, osteoarthritis, symptoms of opioid withdrawal, Alzheimer's disease, and pet disorders. Chemical analysis of CBD products found that many did not contain the levels of CBD claimed in advertising. In December 2020, the US Federal Trade Commission initiated a law enforcement crackdown on American companies marketing CBD products as unapproved drugs. The warning also applied to hemp CBD capsules and oil that were being marketed illegally while not adhering to the federal definition of a dietary supplement.
== See also == AFGROW – Fracture mechanics and fatigue crack growth analysis software Concrete cone failure – Failure mode of anchors in concrete submitted to tensile force Concrete degradation – Damage to concrete affecting its mechanical strength and its durability Earthquake – Sudden movement of the Earth's crust Fatigue – Initiation and propagation of cracks in a material due to cyclic loading Fault (geology) – Fracture or discontinuity in displaced rock Material failure theory – Science of predicting if, when, and how a given material will fail under loading Notch (engineering) – Externally-produced indentation in a planar material Peridynamics – Non-local formulation of continuum mechanics, a formulation of continuum mechanics that is oriented toward deformations with discontinuities, especially fractures Shock (mechanics) – Sudden transient acceleration Strength of materials Stress corrosion cracking – Growth of cracks in a corrosive environment Structural fracture mechanics – Field of structural engineering
==== Other exercise types ==== A 2021 meta-analysis found that meditative exercise programs (tai chi, yoga, qigong) were superior to other forms of exercise (aerobic, flexibility, resistance) in improving sleep quality. Other meta-analyses also found positive effects of tai chi for sleep, fibromyalgia symptoms, and pain, fatigue, depression and quality of life. These tai chi interventions frequently included 1-hour sessions practiced 1–3 times a week for 12 weeks. Meditative exercises, as a whole, may achieve desired outcomes through biological mechanisms such as antioxidation, anti-inflammation, reduction in sympathetic activity, and modulation of glucocorticoid receptor sensitivity. Several reviews and meta-analyses suggest that aquatic training can improve symptoms and wellness in people with fibromyalgia. It is recommended to practice aquatic therapy at least twice a week using a low to moderate intensity. However, aquatic therapy does not appear to be superior to other types of exercise. Combinations of different exercises, such as flexibility and aerobic training, may improve stiffness. However, the evidence is of low-quality. It is not clear if flexibility training alone, compared to aerobic training, is effective at reducing symptoms or has any adverse effects. According to a 2017 systematic review it is uncertain whether vibration training in combination with exercise may improve pain, fatigue, and stiffness.
== External links == Countercurrent multiplier animation from Colorado University. Research about elephant seals using countercurrent heat exchange to keep heat from leaving their body while breathing out, during hibernation. Patent for a snow mask with a removable countercurrent exchange module which keeps the warmth from leaving the mask when breathing out.
Sources: en.wikipedia.org
{\displaystyle {\frac {1}{\sqrt {f_{\mathrm {D} }}}}=-1.93\,\log _{10}\left({\frac {1.91}{\mathrm {Re} {\sqrt {f_{\mathrm {D} }}}}}\left\{1+0.34R_{*}\;\left(1-\exp {\frac {-R_{*}}{26}}\right)\right\}\right),}
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the second-largest country by total area, with the longest coastline of any country. Its border with the United States is the longest international land border. The country is characterized by a wide range of both meteorologic and geological regions. With a population of over 41 million, it has widely varying population densities, with the majority residing in its urban areas and large areas being sparsely populated. Its capital is Ottawa and its three largest metropolitan areas are Toronto, Montreal, and Vancouver. Indigenous peoples have continuously inhabited what is now Canada for thousands of years. Beginning in the 16th century, British and French expeditions explored and later settled along the Atlantic coast. As a consequence of various armed conflicts, France ceded nearly all of its colonies in North America in 1763. In 1867, with the union of three British North American colonies through Confederation, Canada was formed as a federal dominion of four provinces. This began an accretion of provinces and territories resulting in the displacement of Indigenous populations, and a process of increasing autonomy from the United Kingdom. This increased sovereignty was highlighted by the Statute of Westminster, 1931, and culminated in the Canada Act 1982, which severed the vestiges of legal dependence on the Parliament of the United Kingdom.
Anthropological research has suggested that humans "may have evolved to counter-exploit plant neurotoxins". The ability to use botanical chemicals to serve the function of endogenous neurotransmitters may have improved survival rates, conferring an evolutionary advantage. A typically restrictive prehistoric diet may have emphasized the apparent benefit of consuming psychoactive drugs, which had themselves evolved to imitate neurotransmitters. Chemical–ecological adaptations and the genetics of hepatic enzymes, particularly cytochrome P450, have led researchers to propose that "humans have shared a co-evolutionary relationship with psychotropic plant substances that is millions of years old."
==== Impact-resistant polystyrene (PS-I) ==== PS-I (impact resistant polystyrene) consists of a continuous polystyrene matrix and a rubber phase dispersed therein. It is produced by polymerization of styrene in the presence of polybutadiene dissolved (in styrene). Polymerization takes place simultaneously in two ways:
=== Tolerance, dependence and withdrawal === Prolonged use of bromazepam can cause tolerance and may lead to both physical and psychological dependence on the drug, and as a result, it is a medication which is controlled by international law. It is nonetheless important to note that dependence, long-term use and misuse occur in a minority of cases and are not representative of most patients' experience with this type of medication. It shares with other benzodiazepines the risk of abuse, misuse, psychological dependence or physical dependence. A withdrawal study demonstrated both psychological dependence and physical dependence on bromazepam including marked rebound anxiety after 4 weeks chronic use. Those whose dose was gradually reduced experienced no withdrawal. Patients treated with bromazepam for generalised anxiety disorder were found to experience withdrawal symptoms such as a worsening of anxiety, as well as the development of physical withdrawal symptoms when abruptly withdrawn bromazepam. Abrupt or over rapid withdrawal from bromazepam after chronic use even at therapeutic prescribed doses can lead to a severe withdrawal syndrome including status epilepticus and a condition resembling delerium tremens. Animal studies have shown that chronic administration of diazepam (or bromazepam) causes a decrease in spontaneous locomotor activity, decreased turnover of noradrenaline and dopamine and serotonin, increased activity of tyrosine hydroxylase and increased levels of the catecholamines.
Sources: en.wikipedia.org
Biden married Neilia Hunter, a student at Syracuse University, on August 27, 1966, after overcoming her parents' disinclination for her to wed a Catholic. Their wedding was held in a Catholic church in Skaneateles, New York. They had three children: Joseph R. "Beau" Biden III, Robert Hunter Biden, and Naomi Christina "Amy" Biden. A few weeks after Biden was elected senator, his wife Neilia and one-year-old daughter Naomi were killed in an automobile accident in Hockessin, Delaware, on December 18, 1972. Their sons Beau (aged 3) and Hunter (aged 2) were in the car and were taken to hospital with non-life-threatening injuries. He considered resigning to care for them, but Senate Majority Leader Mike Mansfield persuaded him not to. Biden contemplated suicide and was filled with anger and religious doubt. He wrote that he "felt God had played a horrible trick" on him and had trouble focusing on work. Biden met teacher Jill Tracy Jacobs in 1975 on a blind date. They married at the United Nations chapel in New York on June 17, 1977, and spent their honeymoon at Lake Balaton in the Hungarian People's Republic. Biden credits her with the renewal of his interest in politics and life. In 1981, the couple had a daughter, Ashley Biden, who is a social worker, activist, and fashion designer. Jill helped raise her stepsons, Hunter and Beau, who were seven and eight respectively at the time of her marriage.
Plants are referred to as annuals which live only one year, biennials which live two years, and perennials which live longer than that. The longest-lived perennials, woody-stemmed plants such as trees and bushes, often live for hundreds and even thousands of years (one may question whether or not they may die of old age). A giant sequoia, General Sherman, is alive and well in its third millennium. A Great Basin Bristlecone Pine called Methuselah is 4,858 years old. Another Bristlecone Pine called Prometheus was a little older still, showing 4,862 years of growth rings. The exact age of Prometheus, however, remains unknown as it is likely that growth rings did not form every year due to the harsh environment in which it grew but it was estimated to be ~4,900 years old when it was cut down in 1964. The oldest known plant (possibly oldest living thing) is a clonal Quaking Aspen (Populus tremuloides) tree colony in the Fishlake National Forest in Utah called Pando at about 16,000 years. Lichen, a symbiotic algae and fungal proto-plant, such as Rhizocarpon geographicum can live upwards of 10,000 years.
Vision loss can occur and is associated with strabismus, refractive errors, and anisometropia. It can also be caused by severely dry eyes, a consequence of lower eyelid abnormalities and frequent eye infections. Although an abnormally shaped skull is not distinctive for Treacher Collins syndrome, brachycephaly with bitemporal narrowing is sometimes observed. Cleft palate is also common. Dental anomalies are seen in 60% of affected people, including tooth agenesis (33%), discoloration (enamel opacities) (20%), malplacement of the maxillary first molars (13%), and wide spacing of the teeth. In some cases, dental anomalies in combination with mandible hypoplasia result in a malocclusion. This can lead to problems with food intake and the ability to close the mouth. Less common features of TCS may add to an affected person's breathing problems, including sleep apnea. Choanal atresia or stenosis is a narrowing or absence of the choanae, the internal opening of the nasal passages, which may also be observed. Underdevelopment of the pharynx can also narrow the airway. Features related to TCS that are seen less frequently include nasal deformities, high-arched palate, macrostomia, preauricular hair displacement, cleft palate, hypertelorism, notched upper eyelid, and congenital heart defects. Although facial deformity is often associated with developmental delay and intellectual disability, more than 95% of people affected with TCS have normal intelligence. The psychological and social problems associated with facial deformity can affect quality of life in individuals with TCS.
===== Surface area ===== The general trend in MOFs used for hydrogen storage is that the greater the surface area, the more hydrogen the MOF can store. High surface area materials tend to exhibit increased micropore volume and inherently low bulk density, allowing for more hydrogen adsorption to occur.
At Alan Gross's espionage trial in 2011, the Cuban government prosecutors alleged that Alan Gross was running a secret program for USAID called the "Cuba democracy program." The prosecution said that Gross had been coordinating with Akram Elias about this project, and at their meeting in December 2009, they discussed extending USAID's development program into Freemasonry in Cuba. The prosecution also presented evidence at the trial of two flash drives that contained material relating to projects "against the Cuban state." In 2004, they alleged that Alan Gross smuggled a video camera to Grand Master José Manuel Collera Vento, which originated from the office of Marc Wachtenheim. That office, they pointed out, was a block away from the White House. In 2011, Grand Master Collera Venta went on a series of Cuban television broadcasts called Las Razones de Cuba, in which he publicly admitted that he had been working for the Cuban government as a counterintelligence officer his entire life, and that he had only been planted as Grand Master so that the Cuban government could monitor Freemasons. On April 1, 2011, the Cuban government awarded José Manuel Collera Vento with the Escudo Pinareño (English: Shield of Pinar del Rio), the highest award of the Provincial Assembly of People's Power in Pinar del Río. This was awarded for his services to the state. Exiled Cuban Freemasons called this a betrayal of the institution of Freemasonry itself.
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.
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.