A practical reference on lyophilisation: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-07-29 and is reviewed periodically as new material appears.
Residue composition is the property that most cleanly separates verified material from mislabelled samples. Alanine, glutamate, aspartate and glycine appear in that order from the N-terminus, and the two acidic residues sit in the middle of the chain. Because the peptide is short, it can be produced by solid-phase synthesis and characterised by mass spectrometry without ambiguity. Any reported sample whose measured mass departs substantially from 390 daltons is a different compound or a degraded mixture rather than epitalon.
Epitalon is a synthetic tetrapeptide whose four residues are alanine, glutamate, aspartate and glycine, commonly abbreviated AEDG. Its molecular formula is C14H22N4O9 and its monoisotopic mass is near 390.35 daltons. The peptide carries two acidic side chains, so it is neutral to negatively charged in most aqueous buffers. Published reference summaries usually list it under both spellings, epitalon and epithalon, and treat the two names as the same material.
The compound is generally described as a synthetic analogue of a fragment isolated from a pineal gland extract. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology introduced it during the 1980s and 1990s while studying short peptides from animal tissue. The original extract, called epithalamin, is a heterogeneous mixture, whereas epitalon is a single defined sequence. That distinction matters because findings reported for the extract are not automatically findings about the pure tetrapeptide, and claims about broader biological effects remain a separate question from the chemical identity described here.
Identity and purity are established with reversed-phase high-performance liquid chromatography and mass spectrometry. The chromatogram shows the main peak and any truncated or oxidised by-products, while the mass spectrum confirms the expected 390 dalton mass. Amino acid analysis can corroborate composition when a sample's origin is uncertain. Counterion content, particularly residual trifluoroacetate from purification, is frequently reported alongside purity because it shifts the net mass of the solid.
Reference material is normally supplied as a lyophilised powder in a sealed vial. Product literature typically recommends storage at minus twenty degrees Celsius or colder, protected from light and moisture. Freeze-thaw cycling is usually avoided because repeated condensation can introduce water into the vial. Working solutions are commonly prepared fresh, aliquoted, and kept cold for short periods rather than stored at ambient temperature. Labelling the date of opening helps track how long a vial has been in use.
Solubility is high in water, phosphate-buffered saline and normal saline, a pattern that follows from the two acidic residues in the chain. The peptide dissolves poorly in non-polar solvents such as hexane or chloroform. Stock solutions are often prepared in water first and then diluted into the buffer of interest. Because the molecule is small and hydrophilic, filtration through a low-protein-binding membrane is usually straightforward, and visible particulates are uncommon in freshly made solutions.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Derived from the four constituent residues |
| Molecular mass | About 390.35 Da | Monoisotopic value, confirmed by mass spectrometry |
| Residue sequence | Ala-Glu-Asp-Gly | Read from the N-terminus to the C-terminus |
| Common synonyms | Epithalon; AEDG | Both forms appear in reference catalogues |
| Net charge near neutral pH | Negative | Two acidic side chains give a low isoelectric point |
The compound is generally presented as a synthetic fragment of epithalamin, a pineal gland extract investigated in the former Soviet Union from the 1970s onward. Vladimir Khavinson and colleagues in Saint Petersburg developed short peptides modelled on such extracts, and epitalon became the most widely cited of those sequences. Most primary reports appeared in Russian-language journals or in proceedings with limited international circulation. Independent replication in laboratories outside that network remains sparse, and much repeated secondary material traces back to a small number of originating groups.
Laboratory work has examined effects on telomerase activity in cultured cells, on melatonin rhythms in animals, and on markers of oxidative stress. Some experiments report measurable changes while others show none, and the reported findings rest largely on small studies. The absence of large independent trials means the generality of these results is unresolved rather than settled. Review articles occasionally apply the label geroprotector, a term that reflects a research hypothesis about ageing rather than an established clinical finding.
Epitalon is the common name for a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, usually abbreviated AEDG. All four residues are proteinogenic amino acids, and the free peptide has a calculated mass near 390 grams per mole. Because the chain is short and carries no modifications, it is assembled readily by solid-phase synthesis and is distributed mainly as a freeze-dried solid for laboratory work. Catalogue listings use the spellings epitalon, epithalone, and simply AEDG, and the three refer to the same sequence.
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.
Epitalon is a synthetic four-amino-acid peptide with the sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its molecular formula is C14H22N4O9, and its calculated molar mass is approximately 390.35 grams per mole. The compound is a short fragment related to a peptide fraction isolated from bovine pineal gland extracts, and it is normally supplied as a lyophilised powder intended for laboratory research. It is not a registered pharmaceutical product in most countries.
The peptide emerged from research carried out in Saint Petersburg from the late 1980s onward, where investigators searched for shorter active fragments of a pineal preparation known as epithalamin. The name epitalon was chosen to reflect that parent extract. Early reports described effects on neuroendocrine markers and on the lifespan of laboratory animals. Much of that work appeared in Russian-language journals, with English translations following later, which affects how readily the original protocols can be assessed by outside groups.
Published studies on epitalon are dominated by a small number of research groups, and independent replication in other laboratories remains limited. Proposed mechanisms include activation of telomerase and modulation of melatonin rhythms, but the evidence for either rests mainly on cell cultures and animal models. Whether the peptide produces comparable effects in humans is an open question, and the absence of large controlled trials means the literature is best read as exploratory rather than settled.
Identity and purity of epitalon samples are normally established by reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, combined with mass spectrometry. The mass spectrum confirms the expected molecular ion and can reveal truncated or oxidised by-products. Amino acid analysis after acid hydrolysis verifies that the four residues are present in the expected ratio. Certificates typically report a purity figure taken from chromatographic peak area, expressed as a percentage of total integrated signal.
Lyophilised epitalon is generally held at minus twenty degrees Celsius in a sealed container kept dry and dark. Cooler conditions are sometimes recommended for long-term archives. The solid takes up moisture readily enough that repeated opening of a vial introduces water, so dividing a batch into smaller portions before storage lowers degradation risk. Aqueous solutions are less durable than the dry powder and are usually prepared shortly before use, then kept cold and shielded from light to slow hydrolysis and oxidation.
The legacy of the USSR remains a controversial topic. The socio-economic nature of communist states such as the USSR, especially under Stalin, has also been much debated, varyingly being labelled a form of bureaucratic collectivism, state capitalism, state socialism, or a totally unique mode of production. The USSR implemented a broad range of policies over a long period of time, with a large amount of conflicting policies being implemented by different leaders. Some have a positive view of it whilst others are critical towards the country, calling it a repressive oligarchy. The opinions on the USSR are complex and have changed over time, with different generations having different views on the matter as well as on Soviet policies corresponding to separate time periods during its history.
== External links == Human Health Campus, The official website of the International Atomic Energy Agency dedicated to Professionals in Radiation Medicine. This site is managed by the Division of Human Health, Department of Nuclear Sciences and Applications Canadian Organization of Medical Physicist - Organisation canadienne des physiciens médicaux The American Association of Physicists in Medicine medicalphysicsweb.org from the Institute of Physics AIP Medical Physics portal University of Toronto - Medical Biophysics Department Journal of Biophysics Institute of Physics & Engineering in Medicine (IPEM) - UK European Federation of Organizations for Medical Physics (EFOMP)
== Conferences == The Society holds an annual conference in late May or early June as well as topical conferences (at Asilomar State Beach in California and Sanibel Island, Florida) and a fall workshop, which is also focused on a single topic. Conferences on Mass Spectrometry and Allied Topics have been held yearly since 1953.
Despite high total bismuth concentrations in the colon, antimicrobial activity in the colon is negligible because dominant forms of bismuth recovered (insoluble bismuth sulfide and methylated derivatives like TMBi) are microbiologically inactive; transformation into bismuth sulfide not only curtails further absorption but also minimizes potential toxicity and flora disruption.
== Labour market and employment == The Danish labour market is characterized by a high degree of union membership rates and collective agreement coverage dating back from Septemberforliget (The September Settlement) in 1899 when the Danish Confederation of Trade Unions and the Confederation of Danish Employers recognized each other's right to organise and negotiate. The labour market is also traditionally characterized by a high degree of flexicurity, i.e. a combination of labour market flexibility and economic security for workers. The degree of flexibility is in part maintained through active labour market policies. Denmark first introduced active labour market policies (ALMPs) in the 1990s after an economic recession that resulted in high unemployment rates. Its labour market policies are decided through tripartite cooperation between employers, employees and the government. Denmark has one of the highest expenditures on ALMPs and in 2005, spent about 1.7% of its GDP on labour market policies. This was the highest amongst the OECD countries. Similarly, in 2010 Denmark was ranked number one amongst Nordic countries for expenditure on ALMPs. Denmark's active labour market policies particularly focus on tackling youth unemployment. They have had a "youth initiative" or the Danish Youth Unemployment Programme in place since 1996. This includes mandatory activation for those unemployed under the age of 30. While unemployment benefits are provided, the policies are designed to motivate job-seeking. For example, unemployment benefits decrease by 50% after 6 months.
Sources: en.wikipedia.org
=== Countercurrent chromatography === Countercurrent chromatography (CCC) is a type of liquid-liquid chromatography, where both the stationary and mobile phases are liquids and the liquid stationary phase is held stagnant by a strong centrifugal force.
Nanoparticles for drug delivery to the brain is a method for transporting drug molecules across the blood–brain barrier (BBB) using nanoparticles. These drugs cross the BBB and deliver pharmaceuticals to the brain for therapeutic treatment of neurological disorders. These disorders include Parkinson's disease, Alzheimer's disease, schizophrenia, depression, and brain tumors. Part of the difficulty in finding cures for these central nervous system (CNS) disorders is that there is yet no truly efficient delivery method for drugs to cross the BBB. Antibiotics, antineoplastic agents, and a variety of CNS-active drugs, especially neuropeptides, are a few examples of molecules that cannot pass the BBB alone. With the aid of nanoparticle delivery systems, however, studies have shown that some drugs can now cross the BBB, and even exhibit lower toxicity and decrease adverse effects throughout the body. Toxicity is an important concept for pharmacology because high toxicity levels in the body could be detrimental to the patient by affecting other organs and disrupting their function. Further, the BBB is not the only physiological barrier for drug delivery to the brain. Other biological factors influence how drugs are transported throughout the body and how they target specific locations for action. Some of these pathophysiological factors include blood flow alterations, edema and increased intracranial pressure, metabolic perturbations, and altered gene expression and protein synthesis.
==== Nitrogen ==== Nitrogen gas (N2) makes up 78% of the atmosphere and is extremely well mixed over short time-scales, resulting in a homogenous isotopic distribution ideal for use as a reference material. Atmospheric N2 is commonly called AIR when being used as an isotopic reference. In addition to atmospheric N2 there are multiple N isotopic reference materials.
==== Turkey ==== Turkish think tanks are relatively new, having emerged in the 1960s. There are at least 20 think tanks in the country, both independent and supported by government. Many of them are sister organizations of political parties, universities or companies some are independent and others are supported by government. Most Turkish think tanks provide research and ideas, yet they play less important roles in policy making than American think tanks. Turksam, Tasam and the Journal of Turkish Weekly are the leading information sources. The oldest and most influential think tank in Turkey is ESAM (The Center for Economic and Social Research; Turkish: Ekonomik ve Sosyal Araştırmalar Merkezi) which was established in 1969 and has headquarters in Ankara. There are also branch offices of ESAM in Istanbul, Bursa, Konya and elsewhere. ESAM has strong international relationships, especially with Muslim countries and societies. Ideologically it performs policies, produces ideas and manages projects in parallel to Milli Görüş and also influences political parties and international strategies. The founder and leader of Milli Görüş, Necmettin Erbakan, was very concerned with the activities and brainstorming events of ESAM. In The Republic of Turkey, two presidents, four prime ministers, various ministers, many members of the parliament, and numerous mayors and bureaucrats have been members of ESAM. The Turkish Economic and Social Studies Foundation (TESEV) is another leading think tank.
Sources: en.wikipedia.org
It is a four-amino-acid peptide built from alanine, glutamate, aspartate and glycine in that order. Its formula is C14H22N4O9, and it is made by chemical synthesis rather than extracted from tissue. The synthetic peptide is a single defined molecule, unlike the pineal extracts it is often compared with.
No. The two spellings refer to the same tetrapeptide, and the difference reflects transliteration from Russian. Laboratories and catalogues use both forms interchangeably. The material is also indexed as AEDG, taken from the one-letter codes of its residues.
Epithalamin is a mixed preparation derived from animal pineal tissue and contains many peptides. Epitalon is one synthetic sequence chosen for study from that broader mixture. Statements about one do not transfer directly to the other.
Sealed lyophilised powder is normally kept at minus twenty degrees Celsius or below, away from light and moisture. Vials are allowed to reach room temperature before opening to limit condensation. Repeated warming and cooling of the same vial is discouraged.