Research chemical 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 2025-08-18. Where a claim depends on a specific study, the study is described rather than over-claimed.
Identity and purity are checked by reversed-phase high-performance liquid chromatography, usually with ultraviolet detection near 214 nanometres, where the peptide bond absorbs. Mass spectrometry confirms the expected mass and reveals whether truncation products or adducts are present. Acid hydrolysis followed by amino acid analysis gives the residue ratio, which should approximate one alanine, one glutamate, one aspartate and one glycine. Counter-ions such as acetate or trifluoroacetate remain in the dried product and lower net peptide content, so a stated purity figure on a label does not by itself describe how much peptide a vial holds.
Regulatory treatment differs by country. No formulation of epitalon holds a marketing authorisation as a medicine in the United States or the European Union, where material sold for laboratory use is handled as a research chemical and is not intended for human consumption. In Russia, several short peptide preparations from the same institute's peptide series are registered medicinal products, and epitalon appears in that national context. Elsewhere it is frequently offered as a cosmetic ingredient, a category with lighter requirements. Advertising claims about longevity or disease prevention are restricted in most jurisdictions, which limits how sellers describe the compound.
Freeze-dried epitalon is normally kept at minus twenty degrees Celsius in a sealed, desiccated container, protected from light. Short excursions at ambient temperature during shipping are generally tolerated, but repeated warming and cooling cycles encourage moisture uptake, which shortens shelf life. Once dissolved, the peptide is far less stable than the solid: aqueous solutions are subject to hydrolysis and to deamidation at the aspartate and glutamate residues. Working solutions are therefore held refrigerated and used within days, and repeated freezing and thawing of the same vial is best avoided.
Identity is normally established by reversed-phase high-performance liquid chromatography combined with mass spectrometry, a pairing that separates components and confirms molecular mass at once. Purity is quoted as a percentage from the chromatogram, and figures above ninety-five percent are a frequent commercial specification. Amino acid analysis or sequencing supplies further confirmation when required. Because many short peptides behave similarly under chromatography, retention time alone does not establish sequence; the mass measurement is what separates one tetrapeptide from another, and certificates should report both.
Short peptides such as AEDG are normally supplied as a freeze-dried solid and are kept dry, cold, and shielded from light. Holding at minus twenty degrees Celsius is common for the long term, while a refrigerator suffices for brief periods before use. The material takes up moisture to some degree, so containers should stay sealed and be allowed to reach room temperature before opening, which limits condensation on the contents. Repeated warming and cooling of a single container is discouraged because it admits water and can lower the amount of intact peptide.
Dissolution is usually performed in water or a suitable aqueous buffer, and the resulting liquid is divided into single-use portions before freezing. Freeze-thaw cycling is a recognised source of loss for short peptides, since each cycle can encourage aggregation or adsorption onto container walls. Working solutions are generally kept cold and used within a short window, although published stability data specific to epitalon are thin. Containers should be marked with concentration and date, and solutions examined for cloudiness before use.
| Property | Value | Notes |
|---|---|---|
| Storage temperature, solid | Approximately -20 C | Sealed, desiccated, protected from light |
| Typical identity method | Electrospray mass spectrometry | Protonated ion expected near 391 |
| Typical purity method | Reversed-phase HPLC | Ultraviolet detection near 214 nm |
| Common synonyms | Epithalon, epithalone, AEDG | Spelling variants appear in supplier catalogues |
| Solution stability | Days at 2-8 C | Hydrolysis and deamidation limit shelf life |
In France, students attending clinical practice are known as "externes" and newly qualified practitioners training in hospitals are known as "internes". The residency, called "Internat", lasts from three to six years (depending on the speciality) and follows a competitive national ranking examination. It is customary to delay submission of a thesis. As in most other European countries, many years of practice at a junior level may follow. French residents are often called "doctor" during their residency. Literally speaking, they are still students and become M.D. only at the end of their residency and after submitting and defending a thesis before a jury.
The receptors for enkephalin are the δ-opioid receptor (DOR) and μ-opioid receptor (MOR). Opioid receptors are a group of G-protein-coupled receptors, with other opioids as ligands as well. The other endogenous opioids are dynorphins (that bind to κ-opioid receptor), endorphins (MOR), endomorphins, and nociceptin-orphanin FQ. The opioid receptors are ~40% identical to somatostatin receptors (SSTRs).
=== Lymphatic malformation (LM) === Lymphatic malformation, lymphangioma or cystic hygroma, is an abnormal growth of lymphatic vessels that usually affects children around the head and neck area and more rarely involving the tongue causing macroglossia. LM is caused by a PIK3CA mutation during lymphangiogenesis early in gestational cell formation causing the malformation of lymphatic tissue. Treatment often consists of removal of the affected tissue via excision, laser ablation or sclerotherapy, but the rate of recurrence can be high and surgery can have complications. Sirolimus has shown evidence of being an effective treatment in alleviating symptoms and reducing the size of the malformation by way of altering the mTOR pathway in lymphangiogenesis. Although an off label use of the drug, Sirolimus has been shown to be an effective treatment for both microcystic and macrocystic LM. More research is however needed to develop and create targeted, effective treatment therapies for LM.
Sulfur dioxygenase (EC 1.13.11.18, sulfur oxygenase, sulfur:oxygen oxidoreductase) is an enzyme with systematic name S-sulfanylglutathione:oxygen oxidoreductase. This enzyme catalyses the following chemical reaction
Modelled after Umkhonto we Sizwe, the armed wing of the African National Congress, the South West African Liberation Army (SWALA) was formed by SWAPO in 1962. The first seven SWALA recruits were sent from Dar es Salaam to Egypt and the Soviet Union, where they received military instruction. Upon their return, they began training guerrillas at a makeshift camp established for housing South West African refugees in Kongwa, Tanzania.
Sources: en.wikipedia.org
=== 2000s === 2004: Linda B. Buck received the Nobel Prize in Physiology or Medicine along with Richard Axel "for their discoveries of odorant receptors and the organization of the olfactory system". 2009: Carol W. Greider received the Nobel Prize in Physiology or Medicine along with Elizabeth H. Blackburn (Blackburn was a native of Australia, but lived in the United States since 1975, and became a naturalized citizen in September 2003) and Jack W. Szostak "for the discovery of how chromosomes are protected by telomeres and the enzyme telomerase".
Like other compounds housed in various plants, predators which are able to overcome the deterrent are able to sequester carminic acid in their flesh and utilize the deterrent for their own defense. The pyralid moth larva (Laetilia coccidivora) is one such predator which feeds on cochineals, sequestering their prey's carminic acid in their own body for defense against predators. The ability to sequester carminic acid has also been seen in several other larval bearing species (Hyperaspis, Leucopis, etc.). Eisner remarks that the ability to sequester the compound likely arose due to ants being a common predator amongst larvae.
Valve was founded in Kirkland, Washington in 1996 by the former Microsoft employees Gabe Newell and Mike Harrington. For their first product, Valve settled on a concept for a horror first-person shooter (FPS) game. They did not want to build their own game engine, as this would have created too much work for a small team and Newell planned to innovate in different areas. Instead, Valve licensed the Quake engine and the Quake II engine from id Software and combined them with their own code. Newell estimated that around 75% of the final engine code was by Valve. As the project expanded, Valve cancelled development of a fantasy role-playing game, Prospero, and the Prospero team joined the Half-Life project. Half-Life was inspired by the FPS games Doom (1993) and Quake (1996), Stephen King's 1980 novella The Mist, and a 1963 episode of The Outer Limits titled "The Borderland". According to the designer Harry Teasley, Doom was a major influence and the team wanted Half-Life to "scare you like Doom did". The project had the working title Quiver, after the Arrowhead military base from The Mist. The name Half-Life was chosen because it was evocative of the theme, not clichéd, and had a corresponding visual symbol: the Greek letter λ (lower-case lambda), which represents the decay constant in the half-life equation. According to the designer Brett Johnson, the level design was inspired by environments in the manga series Akira.
The fluorescence lifetime measurement is an additional way to follow the evolution of the metal-ion complexation with the ligand, starting from the initial solvent species up to the more stable complexes. Each species can be identified by a typical lifetime related to the decay of the emission intensity. The fluorescence lifetime measurements on the monophasic and biphasic solutions can confirm the formation of the major complexes, thanks to the correlation between the fluorescence lifetime and the number of water molecules potentially present in the inner coordination sphere of the metal ions. Fluorescence spectra can be also obtained at increasing temperature to study complexation thermodynamics and investigate complex stability at experimental conditions closer to industrial applications.
Although genes contain all the information an organism uses to function, the environment plays an important role in determining the ultimate phenotypes an organism displays. The phrase "nature and nurture" refers to this complementary relationship. The phenotype of an organism depends on the interaction of genes and the environment. An interesting example is the coat coloration of the Siamese cat. In this case, the body temperature of the cat plays the role of the environment. The cat's genes code for dark hair, thus the hair-producing cells in the cat make cellular proteins resulting in dark hair. But these dark hair-producing proteins are sensitive to temperature (i.e. have a mutation causing temperature-sensitivity) and denature in higher-temperature environments, failing to produce dark-hair pigment in areas where the cat has a higher body temperature. In a low-temperature environment, however, the protein's structure is stable and produces dark-hair pigment normally. The protein remains functional in areas of skin that are colder—such as its legs, ears, tail, and face—so the cat has dark hair at its extremities. Environment plays a major role in effects of the human genetic disease phenylketonuria. The mutation that causes phenylketonuria disrupts the ability of the body to break down the amino acid phenylalanine, causing a toxic build-up of an intermediate molecule that, in turn, causes severe symptoms of progressive intellectual disability and seizures.
Sources: en.wikipedia.org
=== Other === Izon Science supplies individual and complementary parts for qEV isolation and TRPS measurements, including nanopores, TRPS calibration particles, TRPS fluid cells and qEV racks for storing qEV columns. The qEV RNA Extraction kit, manufactured for Izon Science by Norgen Biotek, is supplied to facilitate the extraction of RNA from EVs. The qEV Concentration Kit utilises Ceres NanoSciences Nanotrap® Extracellular Vesicle Particles to enable the concentration of extracellular vesicles isolated using qEV columns. The qEV RNA Extraction Kit can be used with the qEV Concentration Kit, or separately if required.
In Iran, dill is known as 'shevid' and sometimes, is used with rice and called 'shevid-polo'. It also is used in Iranian 'aash' recipes, and similarly, is called sheved in Persian. In India, dill is known as 'Sholpa' in Bengali, shepu (शेपू) in Marathi, sheppi (शेप्पी) in Konkani, savaa in Hindi, or soa in Punjabi. In Telugu, it is called 'Soa-kura' (herb greens). It also is called sabbasige soppu (ಸಬ್ಬಸಿಗೆ ಸೊಪ್ಪು) in Kannada. In Tamil it is known as sada kuppi (சதகுப்பி). In Malayalam, it is ചതകുപ്പ (chathakuppa) or ശതകുപ്പ (sathakuppa). In Sanskrit, this herb is called shatapushpa. In Gujarati, it is known as suva (સૂવા). In India, dill is prepared in the manner of yellow 'moong dal', as a main-course dish. It is considered to have very good antiflatulent properties, so it is used as 'mukhwas', or an after-meal digestive. Traditionally, it is given to mothers immediately after childbirth. In the state of Uttar Pradesh in India, a small amount of fresh dill is cooked along with cut potatoes and fresh fenugreek leaves (Hindi आलू-मेथी-सोया). In Manipur, dill, locally known as pakhon, is an essential ingredient of chagem pomba – a traditional Manipuri dish made with fermented soybean and rice. In Laos and parts of northern Thailand, dill is known in English as Lao coriander (Lao: ຜັກຊີ or Thai: ผักชีลาว), and served as a side with salad yum or papaya salad. In the Lao language, it is called 'phak see', and in Thai, it is known as 'phak chee Lao'.
A laboratory experiment using animals to study the development and progression of diseases. Animal studies also test how safe and effective new treatments are before they are tested in people. (NCI) Applicable regulatory requirement
In 2020, world production of soybeans was over 353 million tonnes, led by Brazil and the United States combined with 66% of the total (table). Production has dramatically increased across the globe since the 1960s, but particularly in South America after a cultivar that grew well in low latitudes was developed in the 1980s. The rapid growth of the industry has been primarily fueled by large increases in worldwide demand for meat products, particularly in developing countries like China, which alone accounts for more than 60% of imports. Soy is a staple crop; global soy production accounts for four times more legume production than all other legumes combined.
Sources: en.wikipedia.org
The solid is kept cold, dry and dark, typically at minus twenty degrees Celsius, in a sealed container with desiccant. Dissolved material is kept refrigerated and used promptly. Freezing and thawing a solution repeatedly is avoided because it accelerates degradation.
Reversed-phase chromatography with ultraviolet detection gives a purity percentage, while mass spectrometry confirms identity. Amino acid analysis checks the residue composition. Buyers typically request a certificate of analysis showing these measurements for the specific lot.
It is not authorised as a medicine in the United States or the European Union. Material is sold there as a research chemical or cosmetic ingredient. Some related short peptides are registered drugs in Russia, which is a distinct national situation rather than a general approval.
Reversed-phase high-performance liquid chromatography is run alongside mass spectrometry. The chromatogram separates components and gives a purity figure, while the mass spectrum confirms that the measured molecular mass matches the expected sequence. Neither measurement on its own is treated as sufficient.