Everything below concerns Khavinson. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-06-16. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Verification of research-grade material involves comparing a supplier chromatogram against an in-house reference, checking the observed mass against the calculated value, and where possible confirming residue order by tandem mass spectrometry or enzymatic peptide mapping. Purity claims should be read alongside the method used to obtain them, because detection wavelength and integration settings alter the result. Batch-specific data, rather than a generic grade statement, is the informative part of a certificate.
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.
| Property | Value | Notes |
|---|---|---|
| Typical purity specification | 95 percent or higher by HPLC area | Higher grades are also offered |
| Primary analytical method | Reversed-phase HPLC, UV detection | Frequently paired with mass spectrometry |
| Confirmatory technique | Electrospray mass spectrometry | Observed mass compared with theory |
| Storage temperature | Minus 20 degrees Celsius, dry powder | Sealed, desiccated, protected from light |
| Solution handling | Prepare fresh before use | Hydrolysis proceeds in aqueous media |
Material sold for research use varies widely in documented quality. A useful verification package includes a certificate of analysis that states peptide content rather than only net weight, the chromatographic method and column used, and a mass spectrum consistent with the expected mass. Independent testing by a third-party laboratory is occasionally reported. Statements of identity resting only on a supplier label provide little assurance, and the gap between nominal mass and actual peptide content can be substantial once counterions and residual water are counted.
Peptides of this size are generally stable as dry solids but degrade in solution over time. The principal routes are hydrolysis of the peptide backbone and oxidation, with hydrolysis favoured by elevated temperature and extreme pH. Aqueous solutions held at room temperature can show measurable loss of purity within days, while frozen aliquots are considerably more durable. Because the sequence contains neither cysteine nor methionine, oxidation is less of a concern than for many other peptides, but pH control during handling still matters.
Typical storage for the lyophilized powder is −20 °C or lower, in a sealed container protected from light and moisture. Hygroscopic material should be allowed to equilibrate to room temperature before the vial is opened, which limits condensation on the contents. Working solutions are commonly divided into single-use aliquots and frozen to avoid repeated freeze-thaw cycles. Dilute solutions are more prone to adsorption onto plastic surfaces and to loss during filtration, so procedures that minimize transfers and use low-binding labware are preferable.
The parent extract epithalamin was characterised as a low-molecular-weight fraction of pineal tissue rather than a single defined chemical entity. Researchers fractionated it and tested successive fragments for activity, a screening approach typical of peptide discovery work in that era. Epitalon emerged from that process as one of the shorter sequences of interest. Because the original extract was never fully resolved into individual components, claims about which constituent drives a given effect rest on inference. This distinction matters when reading older reports that attribute extract observations to the tetrapeptide itself.
Epitalon is a synthetic tetrapeptide with the residue sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its monoisotopic mass is approximately 390.35 daltons, and it is usually supplied as a lyophilised trifluoroacetate or acetate salt. The compound was derived from a pineal gland extract called epithalamin, a heterogeneous preparation investigated in the former Soviet Union. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology described the tetrapeptide as a constituent fragment of that extract. Commercial material is offered as a laboratory reagent rather than as a finished pharmaceutical product.
Literature searches for this compound must account for several spelling variants. Indexing databases contain epitalon, epithalon, epithalone, and AEDG, and relevant records are scattered across Russian-language and English-language journals that do not consistently cross-cite. Early publications describe the parent extract as a mixture of many peptides, whereas later work addresses the single synthetic tetrapeptide. That shift in nomenclature complicates comparison between studies, because extract data and tetrapeptide data are sometimes cited interchangeably. A search strategy omitting the alternate spellings will return an incomplete set of references.
Three buildings in the World Trade Center collapsed due to fire-induced structural failure. Although the South Tower was struck around seventeen minutes after the North Tower, the plane's impact zone was far lower, at a much faster speed, and into a corner, with the unevenly-balanced additional structural weight causing it to collapse first at 9:59 a.m., having burned for 56 minutes in the fire caused by the crash of United Airlines Flight 175 and the explosion of its fuel. The North Tower lasted just under 29 and a half minutes longer, before collapsing at 10:28 a.m., just under one hour and forty-two minutes after being struck by American Airlines Flight 11. When the North Tower collapsed, debris fell on the nearby 7 World Trade Center building (7 WTC), damaging the building and starting fires. These fires burned for nearly seven hours, compromising the building's structural integrity, and 7 WTC collapsed at 5:21 p.m. The west side of the Pentagon sustained significant damage. At 9:42 a.m., the Federal Aviation Administration (FAA) grounded all civilian aircraft within the continental U.S., and civilian aircraft already in flight were told to land immediately. All international civilian aircraft were either turned back or redirected to airports in Canada or Mexico, and were banned from landing on United States territory for three days. The attacks created widespread confusion among news organizations and air traffic controllers.
The resulting "base process" description provides the necessary data for the determination of preliminary raw material and product specifications, the manufacture of semi commercial quantities in the pilot plant, the assessment of the ecological impact, the regulatory submissions and technology transfer to manufacture at industrial scale, and an estimate of the manufacturing costs in an industrial-scale plant. If the base process is provided by the customer as part of the technology transfer, process research has to optimize it so that it can be transferred to the bench-scale laboratory or pilot plant. Furthermore, it has to be adapted to the specific characteristics of available production trains. Another task is the scaling of development processes. Depending on the volume requirements, three different types of equipment are used for process research, development and optimization: bench-scale laboratories for gram to 100 gram, kilo-labs for kg to 10 kg and pilot plants for 100 kg to ton quantities. Particularities of laboratory processes that have to be eliminated include the use of large numbers of unit operations, dilute reaction mixtures, vast quantities of solvents for extraction, evaporation to dryness, and drying of solutions with hygroscopic salts. Although modern reaction calorimeters may foresee the effects of these different conditions to a certain extent, a direct transfer of a process from the laboratory to the industrial scale is not recommended, because of the inherent safety, environmental, and economic risks.
It is generally considered less sedating and causes less tolerance than traditional 1,4-benzodiazepines, partially because it binds less to subunits that cause sedation. N-desmethylclobazam, is the active metabolite of the benzodiazepine, clobazam. It works by enhancing GABA-activated chloride influx at GABAA receptor, creating a hyperpolarizing, inhibitory postsynaptic potential. The primary active metabolite N-desmethylclobazam, circulates at higher levels than the parent drug at therapeutic dosages. Plasma concentrations of N-desmethylclobazam are approximately 3–5 times higher than those of clobazam. The primary active metabolite of clobazam, is crucial for its prolonged anti-anxiety and anti-epileptic effects, acting similarly on GABAA receptors but with potentially greater importance in long-term therapy, especially for epilepsy, and is largely responsible for the drug's overall clinical action. It was also reported that these effects were inhibited by the GABA antagonist flumazenil, and that clobazam acts more efficiently in GABA-deficient brain tissue.
In metazoans, small interfering RNAs (siRNAs) processed by Dicer are incorporated into a complex known as the RNA-induced silencing complex or RISC. This complex contains an endonuclease that cleaves perfectly complementary messages to which the siRNA binds. The resulting mRNA fragments are then destroyed by exonucleases. siRNA is commonly used in laboratories to block the function of genes in cell culture. It is thought to be part of the innate immune system as a defense against double-stranded RNA viruses.
Sources: en.wikipedia.org
In the minor reaction pathway, a Prilezhaev epoxidation results in the formation of thiophene-2,3-epoxide that rapidly rearranges to the isomer thiophene-2-one. Trapping experiments demonstrate that this pathway is not a side reaction from the S-oxide intermediate, while isotopic labeling with deuterium confirm that a 1,2-hydride shift occurs and thus that a cationic intermediate is involved. If the reaction mixture is not anhydrous, this minor reaction pathway is suppressed as water acts as a competing base. Oxidation may be relevant to the metabolic activation of various thiophene-containing drugs, such as tienilic acid and the investigational anticancer drug OSI-930.
== Surgical procedure == TOPS is implanted following a lumbar decompression, in which bone and ligament tissue compressing the spinal nerves are removed. After decompression, the facet joints are excised and replaced with the TOPS implant. The goal is to preserve mobility at the treated level while preventing instability that would otherwise be addressed with spinal fusion.
Non-volatile materials were discovered in 2015 to also exhibit a 'reactive Leidenfrost effect', whereby solid particles were observed to float above hot surfaces and skitter around erratically. Detailed characterization of the reactive Leidenfrost effect was completed for small particles of cellulose (~0.5 mm) on high temperature polished surfaces by high speed photography. Cellulose was shown to decompose to short-chain oligomers which melt and wet smooth surfaces with increasing heat transfer associated with increasing surface temperature. Above 675 °C (1,247 °F), cellulose was observed to exhibit transition boiling with violent bubbling and associated reduction in heat transfer. Liftoff of the cellulose droplet (depicted at the right) was observed to occur above about 750 °C (1,380 °F), associated with a dramatic reduction in heat transfer. High speed photography of the reactive Leidenfrost effect of cellulose on porous surfaces (macroporous alumina) was also shown to suppress the reactive Leidenfrost effect and enhance overall heat transfer rates to the particle from the surface. The new phenomenon of a 'reactive Leidenfrost (RL) effect' was characterized by a dimensionless quantity, (φRL= τconv/τrxn), which relates the time constant of solid particle heat transfer to the time constant of particle reaction, with the reactive Leidenfrost effect occurring for 10−1< φRL< 10+1.
Sources: en.wikipedia.org
The usual approach is reversed-phase HPLC with ultraviolet detection, reported as a percentage of total peak area. Mass spectrometry is used alongside chromatography to confirm identity rather than purity alone.
The dry powder is commonly kept at minus twenty degrees Celsius, desiccated and away from light. Solutions are generally prepared fresh because they break down faster than the solid form.
Tandem mass spectrometry or enzymatic peptide mapping can establish residue order. A single intact mass value indicates composition and molecular weight but not always the precise arrangement of residues.
It is a four-amino-acid peptide with the sequence alanine-glutamate-aspartate-glycine. The chain is unmodified and contains only standard proteinogenic residues, which makes it straightforward to produce by solid-phase synthesis and to characterise by standard peptide methods.