The short version of cyclic heptapeptide fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-07-24 and is reviewed periodically as new material appears.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Compound class | Synthetic cyclic heptapeptide | Alpha-MSH analogue containing a D-phenylalanine residue |
| Molecular formula | C50H69N15O9 | Average molecular mass approximately 1024.2 g/mol |
| Appearance | White to off-white lyophilised powder | Normally supplied as a freeze-dried solid in a sealed vial |
| Solubility | Freely soluble in water and polar solvents | Dissolves readily in aqueous buffers and in alcohol-water mixtures |
| Receptor targets | MC1R, MC3R, MC4R, MC5R | Acts as a non-selective melanocortin receptor agonist |
Outside regulated medicine, melanotan II circulates through online vendors as a research chemical, often marketed for tanning. Products sold this way vary widely in purity, concentration, and labeling accuracy, and independent testing has documented discrepancies. Published reports describe both pigment effects and adverse reactions, including nausea, flushing, and darkening of existing moles. Long-term safety data are sparse, and no large controlled trial has established a risk profile. Questions about cumulative effects on melanocytes remain unresolved in the literature.
Melanotan II is a synthetic peptide analog modeled on alpha-melanocyte-stimulating hormone, a naturally occurring signaling peptide involved in pigmentation. Its structure is a cyclic heptapeptide containing two non-natural substitutions, norleucine at position four and D-phenylalanine at position seven. These modifications resist enzymatic breakdown and extend the molecule's activity relative to the native hormone. The compound binds melanocortin receptors and is studied mainly as a pharmacological tool rather than a therapeutic product. It has never received approval as a medicine in any major jurisdiction.
Subsequent research has found that the delayed dopaminergic phase is associated with the highly potent dopamine D4 receptor agonism of LSD's metabolite 13-hydroxy-LSD. The first phase is described as a "psychedelic experience", with "meaningfulness and portentousness" as the primary effects, while the latter phase is "clearly a paranoid state", including feeling "at the least self-centered, and usually suspicious, with ideas of reference or even paranoid convictions". The second phase typically develops about 4 to 6 hours after administration but at times up to 10 hours after administration. Parallels have been drawn between this phase and amphetamine psychosis. There is no indication that similar effects occur with other psychedelics like phenethylamines and simple tryptamines, which lack dopamine receptor agonism. The preceding findings have been described by researchers like Daniel X. Freedman and David E. Nichols.
Re2O7 + 17 CO → Re2(CO)10 + 7 CO2 If metal oxides are used carbon dioxide is formed as a reaction product. In the reduction of metal chlorides with carbon monoxide phosgene is formed, as in the preparation of osmium carbonyl chloride from the chloride salts. Carbon monoxide is also suitable for the reduction of sulfides, where carbonyl sulfide is the byproduct.
Seaport terminals handle a wide range of maritime cargoes. Break bulk / general cargo are goods that are handled and stowed piecemeal to some degree, as opposed to cargo in bulk or modern shipping containers. They are typically bundled in batches for hoisting, (with cargo nets, slings or crates), or stacked on trays, pallets or skids. They are generally lifted directly into and out of a vessel's holds, by cranes or derricks present on the dock or on the ship itself. If hoisted onto the deck instead of straight into the hold, cargo then is manhandled and stowed by stevedores. Securing break bulk and general freight inside a vessel includes the use of dunnage. When no hoisting equipment is available, break bulk would previously be man-carried on and off the ship, over a plank, or by passing via human chain. Since the 1960s, the volume of break bulk cargo has enormously declined worldwide in favour of mass adoption of containers. Bulk cargo, such as salt, oil, tallow, but also scrap metal, is usually defined as commodities that are neither on pallets nor in containers. Bulk cargoes are not handled as individual pieces, the way heavy-lift and project cargo are. Alumina, grain, gypsum, logs, and wood chips, for instance, are bulk cargoes. Bulk cargo is classified as liquid or dry.
== Mold == Mold is a generic term for a specific type of fungi. Mildew may also refer to types of mold. Since there are so many species of mold, their appearance varies in color and growth habit. In general, active mold has a musty odor and appears fuzzy, slimy, or damp. Inactive mold looks dry and powdery. Mold propagates via spores, which are always present in the environment. Mold spores can be transferred to an object by mechanical instruments or air circulation. When spores attach to another organism, and the environment is favorable, they begin to germinate. Mold produce mycelium which growth pattern resembles cobwebs. Mycelium allows the mold to obtain food and nutrients through the host. Inevitably, the mycelium produces spore sacs and release new spores into the air. Eventually the spores land on new material, and the reproductive cycle begins again. Identifying mold can be a challenge, because some species resemble dust, dirt, or spiderwebs. In addition, staining caused by mold can be confused with water damage. Ultraviolet light and magnification are two tools to aid in identifying mold on library collections. Poor air circulation, moisture, high temperatures, and environmental humidity are the main causes of mold outbreaks in library collections. When the temperature is above 70 °F (21 °C) and the relative humidity is above 55 percent, mold begins to develop. Collections kept in basements or environments with uncontrolled temperature and humidity are most likely to be impacted by a mold outbreak.
Sources: en.wikipedia.org
==== Volatile organic compounds ==== Volatile organic compounds (VOCs) include a variety of chemicals, some of which may have short- and long-term adverse health effects. There are numerous sources of VOCs indoors, which means that their concentrations are consistently higher indoors (up to ten times higher) than outdoors. Some VOCs are emitted directly indoors, and some are formed through the subsequent chemical reactions that can occur in the gas-phase, or on surfaces. VOCs presenting health hazards include benzene, formaldehyde, tetrachloroethylene and trichloroethylene. VOCs are emitted by thousands of indoor products. Examples include: paints, varnishes, waxes and lacquers, paint strippers, cleaning and personal care products, pesticides, building materials and furnishings, office equipment such as copiers and printers, correction fluids and carbonless copy paper, graphics and craft materials including glues and adhesives, permanent markers, and photographic solutions. Chlorinated drinking water releases chloroform when hot water is used in the home. Benzene is emitted from fuel stored in attached garages. Human activities such as cooking and cleaning can also emit VOCs. Cooking can release long-chain aldehydes and alkanes when oil is heated and terpenes can be released when spices are prepared and/or cooked. Leaks of natural gas from cooking appliances have been linked to elevated levels of VOCs including benzene in homes in the USA. Cleaning products contain a range of VOCs, including monoterpenes, sesquiterpenes, alcohols and esters.
=== International agencies === The European Food Safety Authority (EFSA) warned that children who ate large amounts of confectionery and biscuits with high milk content could theoretically be consuming melamine at more than three times above prescribed EU safety limits (0.5 mg/kg of body weight). The EFSA said children with a mean consumption of products such as milk toffee, biscuits and chocolate containing contaminated powdered milk would not be at risk, and adults would not be at risk even in the worst-case scenarios. The World Health Organization, which was only notified on 11 September, asked Beijing why it took so many months for the scandal to become public, and to establish whether failure was deliberate or due to ignorance. WHO's representative in China, Hans Troedsson, said the issue of who knew what and when was critical, because knowledge would be the distinction between ignorance and neglect. WHO and UNICEF jointly decried the "deliberate contamination of foods intended for ... vulnerable infants and young children." Following a spate of mass national bans, the WHO urged national food safety authorities on 25 September to test Chinese dairy products for health risks before placing import bans or recalls. On 26 September, the WHO warned health officials to look out for tainted dairy products imported from China. International Food Safety Authorities (INFOSAN), a network organized by WHO and the Food and Agriculture Organization, suggested that countries should focus on smuggled formula.
The hundreds of steroids found in animals, fungi, and plants are made from lanosterol (in animals and fungi; see examples above) or cycloartenol (in other eukaryotes). Both lanosterol and cycloartenol derive from cyclization of the triterpenoid squalene. Lanosterol and cycloartenol are sometimes called protosterols because they are the starting compounds for all other steroids. Steroid biosynthesis is an anabolic pathway which produces steroids from simple precursors. A unique biosynthetic pathway is followed in animals (compared to many other organisms), making the pathway a common target for antibiotics and other anti-infection drugs. Steroid metabolism in humans is also the target of cholesterol-lowering drugs, such as statins. In humans and other animals the biosynthesis of steroids follows the mevalonate pathway, which uses acetyl-CoA as building blocks for dimethylallyl diphosphate (DMAPP) and isopentenyl diphosphate (IPP). In subsequent steps DMAPP and IPP conjugate to form farnesyl diphosphate (FPP), which further conjugates with each other to form the linear triterpenoid squalene. Squalene biosynthesis is catalyzed by squalene synthase, which belongs to the squalene/phytoene synthase family. Subsequent epoxidation and cyclization of squalene generate lanosterol, which is the starting point for additional modifications into other steroids (steroidogenesis). In other eukaryotes, the cyclization product of epoxidized squalene (oxidosqualene) is cycloartenol.
The Analyst then taunts Neo in the Matrix with bullet time by threatening to kill Trinity with a pistol, and then forces Neo to meet him in a café that he and Trinity had frequented. The crew then uses that opportunity to unplug Trinity. At the café, surrounded by riot officers, Neo distracts the Analyst while the team unplugs Trinity. They successfully unplug her, and Trinity gets her memories back and helps Neo fight the officers. Eventually, Smith fights the two, but gets away. In a final attempt to get rid of Neo and Trinity, the Analyst activates the Swarm, which forces many people to try to kill Bugs' team. The team survives, and when Neo and Trinity are cornered by police helicopters, they then decide to fly, which indeed does happen. The Analyst is defeated, and Neo and Trinity finally rekindle their romance and remake the Matrix in their own image.
== History == AMP was formed in 1995 to provide structure and leadership to the emerging field of molecular diagnostics. The motivation for forming AMP came from numerous discussions and workshops that took place in the late 1980s and early 1990s. As new molecular technologies and applications emerged, questions about their use, standardization, licensing and accreditation, as well as medical training created consensus for a professional focus. At a workshop in November 1993, participants formed working groups that later became the Association’s initial four subdivisions: Hematopathology, Solid Tumors, Genetics, and Infectious Diseases. In 2012, Informatics was added as a fifth concentration, reflecting the new challenges and opportunities that Big Data management and interpretation has brought to the molecular field.
Sources: en.wikipedia.org
No. It is a laboratory-made peptide, while the natural hormone is alpha-melanocyte-stimulating hormone, a longer peptide produced by the pituitary gland and by skin cells. Melanotan-2 mimics only a short active region of that hormone and contains non-natural residues such as D-phenylalanine.
No approved regulatory indication exists in major markets. An approval exists for a different peptide, afamelanotide, which is used for a rare photosensitivity disorder called erythropoietic protoporphyria. Melanotan-2 itself remains a research compound with no cleared clinical role.
Melanocortin-1 receptors on melanocytes are the receptor most closely linked to pigment production. The peptide is not selective, however, and also activates melanocortin-3, melanocortin-4, and melanocortin-5 receptors. That lack of selectivity is the usual explanation offered for both its range of observed effects and its off-target effects.
No. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.