The short version of research chemical fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-02-26. Anything still debated is marked as such rather than presented as settled.
Reversed-phase high-performance liquid chromatography is the standard approach for assessing purity, usually with ultraviolet detection near 214 nm, where the peptide bond absorbs. Mass spectrometry, most often with electrospray ionization, confirms the molecular mass and helps reveal truncation or deletion byproducts. Amino acid analysis can verify composition, and counterion content is sometimes measured because peptides purified with trifluoroacetic acid retain variable amounts of that salt. Purity figures reported without a stated method and detection wavelength are difficult to interpret.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilized solid |
| Solubility | Freely soluble in water | Also dissolves in polar organic solvents |
| Typical storage temperature | −20 °C or below | Sealed, desiccated, protected from light |
| Primary purity assay | Reversed-phase HPLC | Ultraviolet detection near 214 nm |
| Identity confirmation | Mass spectrometry | Electrospray ionization commonly used |
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.
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.
Reported biological findings come mainly from cell culture and rodent experiments. Those studies describe changes in telomerase catalytic subunit expression, melatonin rhythm amplitude, and antioxidant enzyme activity after peptide exposure. Human data are sparse and consist of small trials with limited blinding and inconsistent endpoints. The proposed mechanisms remain hypotheses rather than established facts, and there is no consensus on whether effects observed in animals carry over to people. Independent replication outside the original research groups is limited, which is a recognised gap in the published literature.
Epitalon appears in the literature primarily through a small number of research groups, most of them associated with the St. Petersburg Institute of Bioregulation and Gerontology. Publications describe cell culture experiments, animal studies, and a limited number of small human studies. Independent replication outside this network is sparse. As a result, reviews of the topic usually separate descriptive reports of observed effects from the question of whether those effects generalize, and they note the difficulty of comparing studies that use different preparations and endpoints.
Analytical characterization of epitalon relies on standard peptide methods. Reverse-phase high-performance liquid chromatography is used to assess purity, and mass spectrometry confirms identity by checking the observed mass against the expected value near 390 daltons. Amino acid analysis can verify composition. Because the peptide is short and hydrophilic, it elutes early on many reverse-phase columns, so method development often requires ion-pairing reagents to achieve adequate retention and resolution from related impurities.
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.
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.
=== Incidents involving medical radiation sources === A radioactive contamination incident occurred in 1984 in Ciudad Juárez, Chihuahua, Mexico, originating from a radiation therapy unit illegally purchased by a private medical company and subsequently dismantled for lack of personnel to operate it. The radioactive material, 60Co, ended up in a junkyard, where it was sold to foundries that inadvertently smelted it with other metals and produced about 6,000 tons of contaminated rebar. These were distributed in 17 Mexican states and several cities in the United States. It is estimated that 4,000 people were exposed to radiation as a result of this incident. In the Samut Prakan radiation accident in 2000, a disused radiotherapy head containing a 60Co source was stored at an unsecured location in Bangkok, Thailand and then accidentally sold to scrap collectors. Unaware of the danger, a junkyard employee dismantled the head and extracted the source, which remained unprotected for a period of days at the junkyard. Ten people, including the scrap collectors and workers at the junkyard, were exposed to high levels of radiation and became ill. Three junkyard workers later died of their exposure, which was estimated to be over 6 Gy. Afterward, the source was safely recovered by Thai authorities. In December 2013, a truck carrying a disused 111 TBq 60Co teletherapy source from a hospital in Tijuana to a radioactive waste storage center was hijacked at a gas station near Mexico City. The truck was soon recovered, but the thieves had removed the source from its shielding.
On 10 November 1952 Thomas's last collection Collected Poems, 1934–1952, was published by Dent; he was 38. It won the Foyle poetry prize. Reviewing the volume, critic Philip Toynbee declared that "Thomas is the greatest living poet in the English language". The winter of 1952/3 brought much personal tragedy: Thomas's father died from pneumonia just before Christmas 1952; and in the Spring of 1953 his sister died from liver cancer, one of his patrons overdosed, three friends died at young ages and Caitlin had an abortion.
Recognizing and evaluating hyperthyroidism in pregnancy is a diagnostic challenge. Thyroid hormones are commonly elevated during the first trimester of pregnancy as the pregnancy hormone human chorionic gonadotropin (hCG) stimulates thyroid hormone production, in a condition known as gestational transient thyrotoxicosis. Gestational transient thyrotoxicosis generally abates in the second trimester as hCG levels decline and thyroid function normalizes. Hyperthyroidism can increase the risk of complications for mother and child. Such risks include pregnancy-related hypertension, pregnancy loss, low-birth weight, pre-eclampsia, preterm delivery, still birth and behavioral disorders later in the child's life. Nonetheless, high maternal FT4 levels during pregnancy have been associated with impaired brain developmental outcomes of the offspring and this was independent of hCG levels. Propylthiouracil is the preferred antithyroid medication in the 1st trimester of pregnancy as it is less teratogenic than methimazole.
== See also == Biological Stain Commission: Third-party quality control and certification of stains Cytology: the study of cells Histology: the study of tissues Immunohistochemistry: the use of antisera to label specific antigens Ruthenium(II) tris(bathophenanthroline disulfonate), a protein dye. Vital stain: stains that do not kill cells PAGE: separation of protein molecules Barium enema - a type of in vivo stain that creates contrast in the x-ray part of the light spectrum Diaphonization
Sources: en.wikipedia.org
Ames (1937), philanthropist, banker at Lazard Freres John Kluge (1937), billionaire, chairman and founder of Metromedia; America's richest person from 1989 to 1990; namesake of the John W. Kluge Center and Kluge Prize at the Library of Congress Vincent Sardi Jr.* (1937), restaurateur, owner of Sardi's, son of Vincent Sardi, Sr. Fred D. Thompson (1937), president and chief executive of Family Circle, vice president of The New York Times Grover Connell (1939), rice trader known for political campaign contributions Howard Pack (1939), chairman and president of Seatrain Lines Daniel Edelman (1940), founder of the world's largest public relations firm Edelman Elliott Sanger (1943), co-founder of classical radio channel WQXR-FM and advocate of FM broadcasting Wylie F. L. Tuttle (1944), real estate developer who spearheaded the construction of Tour Montparnasse Robert Rosencrans (1949), founding chairman of C-SPAN and president of UA-Columbia Cablevision Norton Garfinkle (1951), economist, businessman, public servant; chairman of the Future of American Democracy Foundation Mark N. Kaplan (1951), CEO of Drexel Burnham Lambert and Engelhard Harvey M. Krueger (1951), CEO of Kuhn, Loeb & Co. and vice chairman of Lehman Brothers Alan Wagner (1951), first president of Disney Channel Roone Arledge (1952), former president of ABC News and winner of 36 Emmys; creator of 20/20, Nightline, Monday Night Football, ABC World News Tonight and Primetime Alan N.
In June 1998, Caldwell Dyson was selected by NASA, and began NASA training two months later, in August 1998. Her astronaut candidate training included orientation briefings and tours, numerous scientific and technical briefings, intensive instruction in Shuttle and International Space Station (ISS) systems, physiological training, ground school to prepare for T-38 flight training, as well as learning water and wilderness survival techniques. Completion of this training and evaluation qualified her for flight assignment as a mission specialist. In 1999, Caldwell Dyson was assigned to the Astronaut Office ISS Operations Branch as a Russian Crusader, participating in the testing and integration of Russian hardware and software products developed for ISS. In 2000, she was assigned prime crew support astronaut for the ISS Expedition 5 crew, serving as their representative on technical and operational issues throughout the training and on-orbit phase of their mission. During ISS Expeditions 4 through 6, Caldwell Dyson served as an ISS spacecraft communicator (CAPCOM) inside Mission Control. In 2003, she made a transition to the Astronaut Shuttle Operations Branch and was assigned to flight software verification in the Shuttle Avionics Integration Laboratory and worked supporting launch and landing operations at Kennedy Space Center, Florida. Caldwell Dyson also served as Lead CAPCOM for Expedition 11.
== Structure-activity relationship == Spironolactone and Eplerenone competitively block the binding of aldosterone to the mineralocorticoid receptor and hindering the reabsorption of sodium and chloride ions. The activity of mineralocorticoid antagonists is dependent on the presence of a y-lactone ring on the C-17 position. The C-7 position is also important for activity as substituents there sterically hinder the interaction of C-7-unsubstituted agonists such as aldosterone.
Sources: en.wikipedia.org
The powder is normally kept at −20 °C or below in a sealed, moisture-protected container. Letting the vial reach room temperature before opening helps prevent condensation on the contents.
Reversed-phase HPLC with ultraviolet detection is the usual approach, often paired with mass spectrometry. Together the two methods address both chromatographic purity and molecular identity.
Differences arise from the analytical method, the detection wavelength, and whether the number refers to the peptide or to total powder mass. Counterion and water content can lower the actual peptide fraction considerably.
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.