If you have been reading about certificate of analysis and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-04-21. Where a claim depends on a specific study, the study is described rather than over-claimed.
Stability of the tetrapeptide follows ordinary peptide chemistry rather than any unusual structural feature. The aspartate-glycine pair is prone to aspartimide formation under mildly basic or neutral conditions, and deamidation can follow, altering both mass and chromatographic retention. Dry lyophilised powder kept at or below minus twenty degrees Celsius is the usual handling recommendation, with repeated freeze-thaw cycles avoided. Once dissolved in neutral aqueous buffer, degradation proceeds over days to weeks depending on pH and temperature, while acidic conditions generally slow the aspartimide route. A formal stability-indicating study has not been published in the indexed literature.
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.
Published evidence comes mainly from Russian-language journals and from a single research group, with small sample sizes and limited independent replication. A few laboratories outside that group have examined related peptides and reported weaker or absent telomerase effects, so the central claim is best described as contested rather than settled. Rodent studies report modest changes in some ageing markers and in survival, but designs vary and control conditions are often sparse. No large randomised trial in humans has been published, and long-term safety data in healthy populations are correspondingly thin.
Epitalon is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. It was designed at the St. Petersburg Institute of Bioregulation and Gerontology as a short, chemically defined analogue of epithalamin, a fraction obtained from bovine pineal tissue. Small peptide bioregulators of this type formed a long-running line of work there from the 1980s onward. Because the molecule is produced by solid-phase synthesis rather than extraction, its composition is exact and its purity can be measured directly.
The most frequently cited proposed action is induction of telomerase, the enzyme that adds repeat sequences to chromosome ends. Cell-culture work from the originating group reported higher telomerase reverse transcriptase expression and measurable telomere elongation in human somatic cells after exposure. How a four-residue peptide would reach nuclear gene regulation is not established, and no cell-surface receptor or uptake route has been identified. Additional reports describe changes in melatonin secretion, antioxidant enzyme activity and lipid peroxidation in aged animals, but these findings remain mechanistically unconnected to the telomerase observation.
| 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 |
No pharmacopoeial monograph exists for this peptide, so quality rests on the supplier's internal specifications and on whatever independent testing a purchaser arranges. Certificates of analysis differ widely in which tests they report and in the limits applied. The counter-ion introduced during purification, commonly acetate or trifluoroacetate, changes the net peptide content of a given mass of powder, so two samples of equal weight may not contain equal amounts of the active sequence. Third-party laboratories can verify purity, identity, residual solvents, and counter-ion content for a fee, which makes documentation more informative than labelling.
Verification of a sample usually begins with reversed-phase high-performance liquid chromatography, which resolves the peptide from truncated sequences and other impurities and expresses purity as a percentage of total peak area. Mass spectrometry by electrospray ionisation or matrix-assisted laser desorption supplies an independent check, because the measured mass can be compared against the theoretical value for AEDG. Amino acid analysis or tandem mass spectrometry sequencing can confirm residue order. Each of these methods answers a different question: a purity figure does not establish identity, and an identity match does not establish how much of the material is intact peptide.
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.
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.
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.
Dual polarisation interferometry is a surface-based technique for measuring the optical properties of molecular layers. When used to characterize protein folding, it measures the conformation by determining the overall size of a monolayer of the protein and its density in real time at sub-Angstrom resolution, although real-time measurement of the kinetics of protein folding are limited to processes that occur slower than ~10 Hz. Similar to circular dichroism, the stimulus for folding can be a denaturant or temperature.
The chain's 84 shops, located mainly in MTR and Kowloon–Canton Railway stations (as well as shopping centers and housing estates), were converted to 7-Eleven stores. In 2009, a 7-Eleven location in Quarry Bay opened with a hot food counter, called "7 Café", selling traditional Hong Kong street food and milk tea. This feature was subsequently extended to select other 7-Eleven locations across Hong Kong under the "Daily Café" and "Hot Shot" brands.
=== United Kingdom === Beef Stroganoff began appearing in British cookery books in the early 1930s and became widely popular by the 1970s, particularly in restaurants and at dinner parties. The dish later declined in popularity and became associated with mass-produced ready meals and buffet-style catering. Modern British adaptations often include a creamy sauce made with white wine or brandy, sour cream or crème fraîche, and additions such as smoked paprika and English mustard. While beef fillet was traditionally used, contemporary recipes frequently use alternative proteins such as pork, chicken or sausages. The dish is commonly served with rice, tagliatelle, or potatoes. In recent years, it has experienced limited revival in British food media, pub cuisine, and home cooking.
=== 2000–present === In September 2002, Lilly partnered with Amylin Pharmaceuticals to develop and commercialize Amylin's new drug based on exendin-4, a novel substance isolated from the venom of the Gila monster. Exenatide, the first of the GLP-1 receptor agonists, was approved by the US Food and Drug Administration in April 2005. In 2003, Lilly introduced Cialis (tadalafil), a competitor to Viagra for erectile dysfunction developed in a partnership with Icos. Cialis maintains an active period of 36 hours, causing it sometimes to be dubbed the "weekend pill". It was advertised during the 2004 Super Bowl XXXVIII and 2005 Super Bowl XXXIX halftime shows. In 2004, Lilly introduced duloxetine (Cymbalta), a serotonin-norepinephrine reuptake inhibitor used predominantly in the treatment of major depressive disorders and generalized anxiety disorder. It ranks with Prozac as one of the most financially successful pharmaceuticals in industry history. It is also used in the treatment of fibromyalgia, neuropathy, chronic pain and osteoarthritis. In January 2007, Lilly acquired Icos for $2.1 billion, after raising its offer and facing opposition from Institutional Shareholder Services. Lilly subsequently closed Icos' manufacturing operations, terminated nearly 500 Icos employees, leaving 127 employees working at the biologics facility. In December 2007, CMC Biopharmaceuticals A/S (CMC), a Copenhagen-based provider of contract biomanufacturing services, bought the Bothell, Washington-based biologics facility from Lilly and retained the existing 127 employees.
Be it known that we, Roberta C. Lawson and Mary McLaren, citizens of the united states, residing at Milwaukee, WI have invented a new and useful Improvement in Tea-Leaf Holders, of which the following is a description, reference being had to the accompanying drawings, which are a part of this specification.
Sources: en.wikipedia.org
== Education and career == Nguyen received an undergraduate degree in chemistry from Imperial College London, followed by a master's degree in health policy, planning and finance London School of Economics and from the London School of Hygiene and Tropical Medicine (LSHTM). She worked for the World Health Organization where she conducted research on medical policies. Between 1999 and 2010, she worked at GlaxoSmithKline and led the development of policies on access to medications and vaccines in the developing world. She joined Gavi in 2011, where she worked find ways to support financially sustainable vaccine programs and markets, and notably worked on strategies to supply Ebola vaccines and HPV vaccines against cervical cancer to developing countries. In October 2020, she was appointed managing director of the Office of the COVAX Facility. In 2021, Nguyen was selected as a Bloomberg New Economy Catalyst. As part of the program, Aurelia attended the annual New Economy Forum held in Singapore, and the Bloomberg New Economy Catalyst Retreat that same year.
Azoospermia factor (AZF) is one of several proteins or their genes, which are coded from the AZF region on the human male Y chromosome. Deletions in this region are associated with inability to produce sperm. Subregions within the AZF region are AZFa (sometimes AZF1), AZFb and AZFc (together referred to as AZF2). AZF microdeletions are one of the major causes of male infertility for azoospermia (complete absence of sperm in the ejaculate) and severe oligozoospermia (less than 5 million spermatozoa in the ejaculate) males. AZF is the term used by the HUGO Gene Nomenclature Committee. Of the 15% of couples who are affected by infertility, 50% of those cases are due to the male partner. 15-30% of male factor infertility cases can be correlated with genetic abnormalities. One of the most commonly identified genetic abnormalities in male factor infertility are microdeletions on the long arm of the Y chromosome (Yq), specifically at a region known as the azoospermic factor (AZF) region. In certain circumstances, men with AZF mutations can turn to assisted reproductive technologies (ART), such as intracytoplasmic sperm injection (ICSI), to help them overcome their suboptimal sperm quality. However, it may be more important for clinicians to screen for Yq microdeletions, due to a growing body of evidence that AZF microdeletions have the capability to be vertically transmitted to male offspring. Minor et al. demonstrated that an AZFc mutation was vertically transmitted over three generations via fathers receiving reproductive assistance through ICSI.
The National Institute for Occupational Safety and Health (NIOSH) considers a drug to be hazardous if it exhibits one or more of the following characteristics in humans or animals: carcinogenicity, teratogenicity or developmental toxicity, reproductive toxicity, organ toxicity at low doses, genotoxicity, or structure and toxicity profiles of new drugs that mimic existing hazardous drugs. Specialty pharmacies that stock and dispense medications on the NIOSH list of Hazardous Drugs must follow strict standards. Community pharmacies typically handle some Hazardous Drugs; therefore, using pharmacy automation for Hazardous Drugs generally follows this guideline: pharmacy staff use an exception tray and spatula to count any Hazardous Drug, and decontaminate the tray and spatula immediately following. Pharmacy robots should not store any Hazardous Drugs for chance of pill-grinding and dust-generation. All other medications dispensed in the pharmacy that are not Hazardous Drugs can be counted with pharmacy automation safely if the manufacturer's cleaning directions are followed.
Modern mass spectra are usually analyzed using software: computers can search through libraries of known mass spectra peaks much faster than humans could. For peaks not found in the library, computers can simulate ionization and fragmentation processes (as well as isotope combinations) to generate hypothetical peaks to match against. Many databases of experimental peaks as well as pre-calculated hypothetical peaks are available; these can be combined in looking for a suitable interpretation of a peak.
== References == Fonseca, Jorge M.; High Relative Humidity; Fresh Americas, #1, 2008 Series, Master Media Worldwide Publishing Devon Zagory, Devon Zagory & Associates, University of California, Davis; Advances In Modified Atmosphere Packaging (MAP) of Fresh Produce; Perishables Handling Newsletter Issue No. 90, May 1997, pages 2–3 N. Aharoni, V. Rodov, E. Fallik, R. Porat, E. Pesis and S. Lurie; Department of Postharvest Science of Fresh Produce, ARO, The Volcani Center; Humidity Improves Efficacy of Modified Atmosphere Packaging of Fruits and Vegetables Adel A. Kader, Dept. of Pomology University of California, Davis; Modified Atmosphere Packaging of Fresh Produce; Outlook Second Quarter, Volume 13, No. 2, 1986 Stephen R. Harris; Storage of fresh produce Food and Agriculture Organization of the United Nations; Production is only Half the Battle – A training manual in fresh produce marketing for the Eastern Caribbean, Chapter 8: Storage of fresh produce; Bridgetown, Barbados, December 1988
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.
No. Epithalamin is a peptide-containing extract of bovine pineal glands, while epitalon is a single synthetic tetrapeptide. The extract contains many peptides and other tissue components, so its composition varies between batches in ways that a synthesised sequence does not.