eumelanin 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 2026-07-29. Where a claim depends on a specific study, the study is described rather than over-claimed.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
The peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
Melanotan-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
No regulatory authority has approved melanotan-2 for human use, and several countries classify it as a prescription-only or controlled substance, which restricts lawful supply. Material sold online is generally labelled as a research chemical and is not required to meet pharmaceutical standards of identity or purity. Published human data consist mainly of small uncontrolled studies, case reports and adverse-event notifications, so the evidence base is descriptive rather than confirmatory. Whether repeated melanocyte stimulation alters long-term naevus behaviour remains an open question that no completed trial has resolved.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Alpha-MSH analogue with a lactam ring |
| Molecular formula | C50H69N15O9 | Commonly cited value for the neutral peptide |
| Molecular weight | 1024.18 g/mol | Calculated for the free molecule |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water, DMSO and ethanol | Dissolution in pure water is often slow |
Structurally, Melanotan-2 retains the core recognition motif of alpha-melanocyte-stimulating hormone while adding a lactam bridge that links two side chains and constrains the molecule into a ring. This modification lowers susceptibility to enzymatic degradation. The compound acts as an agonist at melanocortin receptors, particularly subtypes associated with melanin production. Because the same receptor family influences several physiological processes, researchers note that its activity is not confined to pigmentation alone. Receptor selectivity continues to be examined in published studies.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its sequence incorporates modified residues that increase potency and extend biological activity relative to the native hormone. The compound binds receptors of the melanocortin family and is examined mainly in laboratory research. It does not occur naturally and exists only as a manufactured chemical entity produced by solid-phase synthesis.
The peptide was developed during the 1980s by researchers investigating melanocortin signalling and skin pigmentation pathways. Early work focused on analogues of alpha-melanocyte-stimulating hormone that would resist enzymatic breakdown more effectively than the parent molecule. Melanotan-2 emerged from that programme as a shortened, cyclised variant. Reports describing its synthesis and receptor activity later appeared in the scientific literature. Commercial availability grew through unregulated channels rather than through pharmaceutical approval.
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.
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.
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.
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.
=== mz5 === The mz5 format addresses the performance problems present in other XML based formats (such as the above ones). It uses mzML's ontology, but saves the data using the HDF5 backend for reduced storage space requirements and improved read/write speed.
== Types == Consistent with the three modes of fruit development, plant scientists have classified fruits into three main groups: simple fruits, aggregate fruits, and multiple (or composite) fruits. The groupings reflect how the ovary and other flower organs are arranged and how the fruits develop, but they are not evolutionarily relevant as diverse plant taxa may be in the same group. While the section of a fungus that produces spores is called a fruiting body, fungi are members of the fungi kingdom and not of the plant kingdom.
=== White chuño === White chuño is obtained by washing the frozen potatoes. The washing may take various forms. In Bolivia, the potatoes are spread on blankets or straw and constantly sprayed with water to moisten. In Peru, the frozen potatoes are transported to a river, and deposited in pools. This washing typically takes about a week. The final step is drying in the sun. The result is now called chuño, also known as papas secas (Spanish for 'dry potatoes'). In Bolivia, white chuño is also called tunta.
During the COVID-19 pandemic, many jurisdictions around the world introduced biosecurity measures at internal borders. This ranged from quarantine measures imposed upon individuals crossing state lines within America to prohibitions on interstate travel in Australia.
Sources: en.wikipedia.org
== Honors and awards == 2010 American Chemical Society The Delaware Section Award 2015 Dupont Pederson Medal 2016 the Analytical Scientist The Power List 2016 Top 50 most influential women 2020 Eastern Analytical Symposium (EAS) Award for Outstanding Achievements in Mass Spectrometry
By the mid-1900s, lichenologists were already exploiting chemical traits for classification—decades before such methods reached vascular plant taxonomy. Because many lichens synthesize distinctive secondary metabolites (specialized compounds including lichen products unique to these organisms), workers devised simple spot tests in which reagents applied to the thallus yield diagnostic colour changes. The technique dates to the 1860s, but by 1951, the tests were routine. Elke Mackenzie listed K (potassium hydroxide solution), C (sodium hypochlorite), and Pd (p-phenylenediamine) as key diagnostic reagents because species often differ in their colour reactions. For example, a yellow K reaction usually signals the presence of the common metabolite atranorin, whereas a deep-red Pd reaction suggests certain depsidones. The chemical toolbox expanded sharply with the adoption of thin-layer chromatography (TLC) in the late 1960s. Chicita F. Culberson's Chemical and Botanical Guide to Lichen Products (1969) laid out a reproducible protocol for separating trace compounds from minute thallus chips, making TLC profiles a standard component of species descriptions. David Hawksworth's 1976 synthesis went a step further by integrating metabolite patterns into family‑ and order‑level frameworks, demonstrating that chemistry could diagnose natural groups and foreshadowing the molecular phylogenies that would follow. Chemical tests revealed cryptic diversity beneath outwardly uniform lichens.
Argon has approximately the same solubility in water as oxygen and is 2.5 times more soluble in water than nitrogen. Argon is colorless, odorless, nonflammable and nontoxic as a solid, liquid or gas. Argon is chemically inert under most conditions and forms no confirmed stable compounds at room temperature. Although argon is a noble gas, it can form some compounds under various extreme conditions. Argon fluorohydride (HArF), a compound of argon with fluorine and hydrogen that is stable below 17 K (−256.1 °C; −429.1 °F), has been demonstrated. Although the neutral ground-state chemical compounds of argon are presently limited to HArF, argon can form clathrates with water when atoms of argon are trapped in a lattice of water molecules. Ions, such as ArH+, and excited-state complexes, such as ArF, have been demonstrated. Theoretical calculation predicts several more argon compounds that should be stable but have not yet been synthesized.
== Interaction with juvenile hormone == Juvenile hormone is synthesised in the corpora allata. In every insect tested, at least one of the three types of Allatostatin inhibits the biosynthesis of juvenile hormone. This is achieved by paracrine release of Allatostatin from neurons in the brain which terminate in the corpora allata. The signal is transduced by GPCR receptors, but the intracellular pathway is not yet known. Other amine and neuropeptide neurotransmitters may also inhibit juvenile hormone biosynthesis.
The constitutional status of a union territory is similar to a state under the perennial president's rule per Article 356 subject to specific exemptions to a few union territories with legislative assembly. As Per Article 240 (1), supreme power is accorded to the president in regulating the affairs of all the union territories except Chandigarh, NCT and Puducherry, including powers to override the laws made by Parliament and the constitution of India. Article 240(2) allows implementing tax haven laws in these union territories to attract foreign capital and investments into India instead of depending on foreign tax haven countries. The difference between states as listed in the First Schedule of the constitution and union territories with legislative assembly is that states were given autonomous powers as provided in the constitution without any possible interference by the parliament whereas UTs with legislative assembly (Part VIII) has similar powers but parliament is empowered to modify or repeal or suspend the laws made by a union territory (ultimate authority by the parliament unlike the independent nature of the states). Three of the union territories have representation in the upper house of the Indian Parliament, the Rajya Sabha: Delhi, Jammu and Kashmir, and Puducherry. Puducherry, Jammu and Kashmir and NCT of Delhi are the only three union territories that are exceptional among union territories in that each has its own locally elected legislative assembly and have a chief minister.
Sources: en.wikipedia.org
Homocystinuria (HCU) is an inherited disorder of the metabolism of the amino acid methionine due to a deficiency of cystathionine beta synthase or methionine synthase. It is an inherited autosomal recessive trait, which means a child needs to inherit a copy of the defective gene from both parents to be affected. Symptoms of homocystinuria can also be caused by a deficiency of vitamins B6, B12, or folate.
PA 6/66: [NH−(CH2)6−NH−CO−(CH2)4−CO]n−[NH−(CH2)5−CO]m made from caprolactam, hexamethylenediamine and adipic acid; PA 66/610: [NH−(CH2)6−NH−CO−(CH2)4−CO]n−[NH−(CH2)6−NH−CO−(CH2)8−CO]m made from hexamethylenediamine, adipic acid and sebacic acid. The term polyphthalamide (abbreviated to PPA) is used when 60% or more moles of the carboxylic acid portion of the repeating unit in the polymer chain is composed of a combination of terephthalic acid (TPA) and isophthalic acid (IPA).
The flesh of the [black] bear is savoury, but rather luscious, and tastes not unlike pork. It was once so common an article of food in New-York as to have given the name of Bear Market to one of the principal markets of the city. Theodore Roosevelt likened the flesh of young American black bears to that of pork, and not as coarse or flavorless as the meat of grizzly bears. The most favored cuts are concentrated in the legs and loins. Meat from the neck, front legs and shoulders is usually ground into minced meat or used for stews and casseroles. Keeping the fat on tends to give the meat a strong flavor. As American black bears can have trichinosis, cooking temperatures need to be high in order to kill the parasites. Bear fat was once valued as a cosmetic article that promoted hair growth and gloss. The fat most favored for this purpose was the hard white fat found in the body's interior. As only a small portion of this fat could be harvested for this purpose, the oil was often mixed with large quantities of hog lard. However, animal rights activism over the last decade has slowed the harvest of these animals; therefore the lard from bears has not been used in recent years for the purpose of cosmetics.
== Contraindications == Quinolones are not recommended in people with epilepsy, Marfan's syndrome, Ehlers–Danlos syndrome, QT prolongation, pre-existing CNS lesions, or CNS inflammation, or who have had a stroke. They are best avoided in the athlete population. Safety concerns exist for fluoroquinolone use during pregnancy, so they are contraindicated unless no other safe alternative antibiotic exists. However, one meta-analysis looking at the outcome of pregnancies involving quinolone use in the first trimester found no increased risk of malformations. They are also contraindicated in children due to the risks of damage to the musculoskeletal system. Their use in children is not absolutely contraindicated, however for certain severe infections where other antibiotics are not an option, their use can be justified. Quinolones should also not be given to people with a known hypersensitivity to the drug class. The basic pharmacophore, or active structure, of the fluoroquinolone class is based upon the quinoline ring system. The addition of the fluorine atom at C6 distinguishes the successive-generation fluoroquinolones from the first-generation of quinolones. The addition of the C6 fluorine atom has since been demonstrated not to be required for the antibacterial activity of this class (circa 1997).
and hit .409 with 11 home runs, 20 walks and 1.384 OPS and collected his second consecutive Player of the Month award. He would hit another three home runs with six walks in nine August games before a pitch from Andy Benes fractured his left hand on August 10 and ended his season in the same manner the season before. Entering that game, Bagwell carried an 18-game hitting streak. Two days later, the strike ended the season for all the major leagues. His production accelerated in 26 games after the All-Star break, as he posted a .432 batting average, .530 OBP, .916 SLG, 1.446 OPS, 10 doubles, 12 home runs, 34 RBI and 30 runs scored. The Astros finished one-half game out of first place in the inaugural season of the National League Central division, a product of MLB's division realignment. Bagwell played in 110 games in the 1994 season, batting .368 with a .750 SLG, 1.201 OPS, 39 home runs, 116 RBI, 104 runs scored, 300 total bases and 213 adjusted OPS (OPS+) in 400 at bats. He led the major leagues in SLG, OPS+, RBI, and total bases, and the NL in runs scored and OPS, but fell short of winning the batting Triple Crown, finishing second for the batting title to Tony Gwynn, who, after batting .394, had the highest average in the major leagues since Ted Williams in 1941. Bagwell finished second in home runs to Matt Williams, who hit 43.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.
No national medicines agency has approved melanotan-2 for clinical use. Afamelanotide, a related but distinct peptide, holds a marketing authorisation in the European Union for a rare photosensitivity disorder. Melanotan-2 itself is handled as a laboratory chemical.
Its broad activity across melanocortin receptors makes it a tool for probing pigmentation, appetite and vascular signalling. Early trials recorded skin darkening and other effects that were not the original focus of the work. Those observations generated hypotheses that later studies have examined.
No regulatory agency has authorised melanotan-2 as a medicine for any indication. It circulates mainly as a research chemical or through unregulated channels. As a result, identity, purity and content are not independently guaranteed.