The short version of research chemical fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-10-12 and is reviewed periodically as new material appears.
Because epitalon has no pharmacopoeial monograph, quality assessment depends on supplier documentation and independent testing. Certificates of analysis typically report a purity figure from a single chromatographic run, a measured mass and sometimes an appearance description, but methods and acceptance criteria are not harmonised across vendors. Third-party laboratories can repeat identity and purity measurements, and mismatches between labelled and measured peptide content have been described for research peptides generally. What constitutes adequate identity confirmation for a molecule of this size stays an open question, since mass agreement alone does not separate closely related sequences.
Identity testing for epitalon relies on reversed-phase high-performance liquid chromatography for purity and mass spectrometry for mass confirmation. Because the sequence contains no tryptophan or tyrosine, ultraviolet detection at 280 nanometres is insensitive, so chromatographic methods usually monitor absorbance near 214 nanometres, where the peptide backbone absorbs. Electrospray ionisation or matrix-assisted laser desorption/ionisation then checks the intact mass against the expected value near 390 daltons. Peptide mapping or amino acid analysis after acid hydrolysis can supplement these measurements, although such confirmatory work is seldom reported on commercial certificates of analysis.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Analytical method | Reversed-phase HPLC | Purity determination, typically 214 nm |
| Mass confirmation | ESI or MALDI mass spectrometry | Compared with mass near 390 Da |
| Common synonyms | Epitalon, epithalon, AEDG | Naming differs between suppliers |
| Storage temperature | −20 °C or lower | Lyophilised powder, kept desiccated |
| Solution stability | Limited in neutral aqueous buffer | Aspartimide and hydrolysis pathways |
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.
Purity assessment of peptide reagents normally relies on reversed-phase high-performance liquid chromatography. A gradient of acetonitrile in water with trifluoroacetic acid, paired with a C18 stationary phase, separates the target tetrapeptide from truncated sequences and deletion analogues. Detection at 214 nanometres exploits absorbance of the peptide backbone, since the molecule contains no aromatic residue. Results are expressed as a percentage of total peak area. Values above ninety-five percent are typical for research-grade material, although reporting conventions vary between suppliers.
Identity confirmation uses mass spectrometry, usually electrospray ionisation in positive mode or matrix-assisted laser desorption. The protonated free peptide produces a signal near three hundred and ninety-one daltons, while salt adducts shift that value slightly. Tandem mass spectrometry or amino acid analysis supplies sequence-level confirmation, which a single mass measurement cannot. Peptides containing aspartate can cyclise into succinimide intermediates that hydrolyse to isoaspartate isomers of identical mass. Because those isomers are difficult to separate chromatographically, identity and purity results carry more weight when interpreted together.
Storage practice centres on limiting moisture, oxygen, and repeated temperature cycling. Freeze-dried powder is generally held desiccated at minus twenty degrees Celsius or colder and protected from light. Reconstituted solutions are markedly less stable, and the aspartate-glycine junction is prone to succinimide formation at neutral to mildly alkaline pH. Portioning material into single-use aliquots reduces degradation compared with repeated freeze-thaw cycles. Stability data specific to this tetrapeptide remain scarce, so most handling guidance is extrapolated from general peptide chemistry rather than measured directly.
The most widely cited claim is that epitalon activates telomerase and thereby extends telomere length. Supporting evidence comes largely from cultured human cells, where treatment was associated with increased telomerase activity and delayed replicative senescence. Telomerase activation is a biologically consequential effect, since the enzyme is largely silenced in most somatic cells. However, the route by which a short peptide would reach and act on the enzyme's regulatory machinery has not been established. Independent replication in human trials is scarce, so the link between cell-culture observations and whole-body aging remains an open question.
Human data are limited to small studies, often without the randomization, blinding, or control groups expected in contemporary clinical research. Reported outcomes have included changes in melatonin levels, immune markers, and subjective measures, but sample sizes were generally too small to support firm conclusions. Some reviews treat the peptide as promising while noting methodological weaknesses; others question whether the observed effects are specific. The compound is frequently discussed in longevity-focused communities, where enthusiasm often outpaces the published evidence. Separating established findings from speculation is therefore important when reading summaries of this research.
Epitalon emerged from research conducted in Saint Petersburg by Vladimir Khavinson and colleagues, who studied short peptides as potential regulators of aging. The work built on epithalamin, a pineal gland extract reported to influence neuroendocrine function. Epitalon was designed as a synthetic counterpart with a defined sequence, allowing reproducible experiments that extracts could not support. Early publications described effects on melatonin rhythms and lifespan in animal models. These findings circulated mainly in Russian-language journals during the 1990s, which limited their visibility among English-speaking researchers.
No national medicines regulator has approved epitalon as a therapeutic product. It is generally distributed as a research chemical, and in some jurisdictions selling peptides for human consumption without approval is restricted or prohibited. Certificates of analysis accompanying commercial material vary in which tests are performed, and independent verification of identity and purity is uncommon. Statements about anti-ageing or disease-prevention benefits on vendor pages are marketing claims rather than regulatory findings, a distinction that shapes how the compound is discussed in scientific and popular sources alike.
The most frequently cited laboratory finding is that AEDG increased telomerase activity and extended telomere length in cultured human somatic cells. That work used fetal fibroblast strains and reported changes in enzyme activity alongside altered division counts. Replication by unrelated groups has been limited, and the published record is largely a single-laboratory series rather than a multi-centre programme. The result supports a hypothesis about peptide influence on gene expression in cell culture; it does not by itself establish an effect on telomere length in living animals or in people.
The monoepoxide of treosulfan (EBDM) exhibited greater brain penetration than the parent compound, with tissue-to-plasma ratios of 0.25 in young adult rats and 0.50 in juvenile rats. The elimination half-life of treosulfan in patients is short, averaging 1.5–2.0 h. The apparent elimination half-life of the biologically active epoxides is similar to that of treosulfan, reflecting the phenomenon of formation rate-limited elimination. The most common side effects include infections, nausea (feeling sick), stomatitis (inflammation of the lining of the mouth), vomiting, diarrhea, and abdominal pain (belly ache). Tiredness, febrile neutropenia (low white blood cell counts with fever) and high blood levels of bilirubin (a breakdown product of red blood cells) are also seen in more than 1 in 10 adults, and rash also affects more than 1 in 10 children. The most common adverse reactions include musculoskeletal pain, stomatitis, pyrexia, nausea, edema, infection, and vomiting. Selected grade 3 or 4 nonhematological laboratory abnormalities include increased GGT, increased bilirubin, increased ALT, increased AST, and increased creatinine. Treosulfan was authorized for medical use in the European Union in June 2019, and approved for medical use in the United States in January 2025.
==== Countries ==== The Netherlands has the lowest rate of antibiotic prescribing in the OECD, at a rate of 11.4 defined daily doses (DDD) per 1,000 people per day in 2011. DDD is a statistical measure of drug consumption, defined by the World Health Organization (WHO). • Germany and Sweden also have lower prescribing rates, with Sweden's rate having been declining since 2007. • Greece, France and Belgium have high prescribing rates.
== Regulation of TIMP expression == Transcription of this gene is highly inducible in response to many cytokines and hormones. In addition, the expression from some but not all inactive X chromosomes suggests that this gene inactivation is polymorphic in human females. This gene is located within intron 6 of the synapsin I gene and is transcribed in the opposite direction. In adrenocortical cells the trophic hormone ACTH induces expression of TIMP-1 and the increase in TIMP expression is also associated with decreased collagenase activity. Increased expression of TIMP1 has been found to be associated with worse prognosis of various tumors, such as laryngeal carcinoma or melanoma.
=== Signaling pathways === Ribose is a building block in secondary signaling molecules such as cyclic adenosine monophosphate (cAMP) which is derived from ATP. One specific case in which cAMP is used is in cAMP-dependent signaling pathways. In cAMP signaling pathways, either a stimulative or inhibitory hormone receptor is activated by a signal molecule. These receptors are linked to a stimulative or inhibitory regulative G-protein. When a stimulative G-protein is activated, adenylyl cyclase catalyzes ATP into cAMP by using Mg2+ or Mn2+. cAMP, a secondary messenger, then goes on to activate protein kinase A, which is an enzyme that regulates cell metabolism. Protein kinase A regulates metabolic enzymes by phosphorylation which causes a change in the cell depending on the original signal molecule. The opposite occurs when an inhibitory G-protein is activated; the G-protein inhibits adenylyl cyclase and ATP is not converted to cAMP.
Riots and protests resumed the following day, 17 December. The rioters broke into the district committee building and threw party documents, propaganda brochures, Ceaușescu's writings, and other symbols of Communist power out of windows. The military was sent in to control the riots, because the situation was beyond the capability of the Securitate and conventional police to handle. The presence of the army in the streets was an ominous sign; it meant that they had received their orders from the highest level of the command chain, presumably from Ceaușescu himself. The army failed to establish order, and chaos ensued, including gunfire, fights, casualties, and burned cars. Transportor Amfibiu Blindat (TAB) armoured personnel carriers and tanks were called in. After 20:00, from Piața Libertății (Liberty Square) to the Opera, there was wild shooting, including the area of Decebal bridge, Calea Lipovei (Lipovei Avenue) and Calea Girocului (Girocului Avenue). Tanks, trucks and TABs blocked the accesses into the city, while helicopters hovered overhead. After midnight, the protests calmed down. Colonel-General Ion Coman, local Party secretary Ilie Matei, and Colonel-General Ștefan Gușă (Chief of the Romanian General Staff) inspected the city. Some areas looked like the aftermath of a war: destruction, rubble and blood.
Sources: en.wikipedia.org
The Tempest (2001) - Boatswain I Dreamt of Bombay (2002) - Bobby Girlfriends (2002) - Guy Hulk (2003) - Soldier Ball & Chain (2004) - Monty War of the Worlds (2005) - Boston Soldier Over There (2005) - Sergeant First Class Neeson Cold Case (2006) - Wes Floyd Veronica Mars (2007) I Gotta Be Better Than Keanu (2007) - Slimy Agent Scrubs (2001–2009) - Dr. Doug Murphy The Beast (2009) - Todd Jaracki
== Definitions == According to the Centers for Disease Control and Prevention (CDC), a virucide is "An agent that kills viruses to make them noninfective." According to a definition by Robert Koch Institute Germany and further institutions, virucide means effective against enveloped and non-enveloped viruses. Due to the complexity of the subject, in Germany, Robert-Koch-Institute introduced sub-definitions such as "limited virucidal" or "limited virucidal plus" (translated from German) to differentiate its meaning further. Note that the meaning of virus inactivation or viral clearance is specific for the medical process industry, i.e., to remove HIV from blood.
Prolactin-releasing hormone, also known as PRLH, is a hypothetical human hormone or hormone releasing factor. Existence of this factor has been hypothesized as prolactin is the only currently known hormone for which almost exclusively negative regulating factors are known (such as dopamine, leukemia inhibitory factor, some prostaglandins) but few stimulating factor. Its secretion is mediated by estrogen from placenta during pregnancy to elevate blood level of prolactin. While many prolactin stimulating and enhancing factors are well known (such as thyrotropin-releasing hormone, oxytocin, vasoactive intestinal peptide and estrogen) those have primary functions other than stimulating prolactin release and the search for hypothetical releasing factor or factors continues. The prolactin-releasing peptide identified in 1998 was a candidate for this function, however as of 2008 it appears its function is not yet completely elucidated.
The Federation of Malaya Executive Council comprised 7 official and 7 unofficial members. The Federation of Malaya Legislative Council comprised the high commissioner as the council president, 14 official and 50 unofficial members representing the Straits Settlements, business groups and all races. Additionally, 9 State Council Yang Di Pertua (heads of state), chief ministers and 2 representatives from the Straits Settlements became unofficial members. The Malay Conference of Rulers would advise the high commissioner on immigration issues. The British Resident was replaced with a chief minister in each state of the federation.
Additionally, intestinal microbiota may produce pathogen-associated molecular patterns that stimulate cholangiocytes and hepatic macrophages to produce proinflammatory cytokines, which promote recruitment of immune cells to the bile ducts, fibrosis, cholangiocyte apoptosis and senescence, and ultimately destruction of the bile ducts. In support of T cell involvement, certain human leukocyte antigen (HLA) variants are strongly associated with PSC risk. Further evidence for genetic predisposition include the identification of 23 non-HLA susceptibility loci and a higher disease risk among siblings, though environmental factors appear to play a much greater role in pathogenesis. Another theory postulates that increased intestinal permeability contributes to PSC. Tight junctions, which normally maintain the integrity of the intestinal epithelium, may become disrupted in inflammation. Leaky tight junctions could allow commensal bacteria and toxins to enter portal circulation and reach the liver, where they can trigger inflammation and fibrosis. The intestinal dysbiosis theory hypothesizes that yet unidentified environmental triggers (e.g., diet, medication, inflammation) reduce microbiota diversity and/or alter the population of specific species. The resulting imbalance between primary and secondary bile acids may lead to PSC via the gut-liver axis. The primary bile acids cholic acid (CA) and chenodeoxycholic acid (CDCA) are synthesized in the liver and undergo conjugation before being released into the small intestine to aid digestion.
Sources: en.wikipedia.org
The molecule lacks aromatic residues, so it absorbs weakly near 280 nanometres, the wavelength applied to many other peptides. The peptide bond absorbs strongly below 220 nanometres, making 214 nanometres a practical compromise. Gradient methods must therefore use mobile phases with low ultraviolet absorbance to keep the baseline clean.
Neutral and slightly basic aqueous conditions promote aspartimide formation at the aspartate-glycine step, often followed by deamidation. Elevated temperature and repeated freeze-thaw cycles accelerate the loss. Acidic solutions and dry lyophilised powder are comparatively stable over short periods.
No monograph exists in the United States Pharmacopeia or the European Pharmacopoeia, and no widely distributed certified reference standard is available. Purity and identity therefore rest on supplier methods that are not harmonised. This absence is the main reason reported purities are difficult to compare between sources.
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.