A practical reference on Khavinson: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-02-21 and is reviewed periodically as new material appears.
Identity is normally established by reversed-phase high-performance liquid chromatography combined with mass spectrometry, a pairing that separates components and confirms molecular mass at once. Purity is quoted as a percentage from the chromatogram, and figures above ninety-five percent are a frequent commercial specification. Amino acid analysis or sequencing supplies further confirmation when required. Because many short peptides behave similarly under chromatography, retention time alone does not establish sequence; the mass measurement is what separates one tetrapeptide from another, and certificates should report both.
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.
Chemically, the molecule consists of four amino acid residues joined by three peptide bonds, with a free N-terminal amino group and a free C-terminal carboxyl group. Its molecular formula is C14H22N4O9, and its monoisotopic mass is approximately 390 daltons. The acidic glutamate and aspartate side chains give the peptide a net negative charge near neutral pH, a property that shapes its chromatographic behaviour and solubility profile. No disulfide bridges or other post-translational modifications are present, so the primary sequence alone defines the structure.
Most experimental work has been carried out in cell culture and animal models. Several reports describe changes in telomerase activity and proliferation in cultured cells, while rodent studies have examined lifespan, melatonin rhythm and reproductive endpoints. Human data remain limited, and much of the published clinical material consists of small trials with incomplete reporting of methods and controls. Whether the cell and animal findings translate into measurable effects in people is an open question, and the mechanistic basis of the reported telomerase changes is not fully established.
Discussions in the literature often conflate three distinct entities: the pineal extract epithalamin, the isolated tetrapeptide AEDG, and commercial preparations sold under similar names. Reviews citing older Russian-language studies sometimes omit detail on purity, route of administration and control groups, which makes cross-study comparison difficult. Researchers working with the compound generally note the need for independent replication, standardized enzyme assays, and clearer reporting of peptide identity. These caveats are relevant when weighing claims that appear in secondary sources rather than in primary reports.
| Property | Value | Notes |
|---|---|---|
| Sequence | Ala-Glu-Asp-Gly | Written in three-letter amino acid code |
| Single-letter code | AEDG | Form used in most catalogue entries |
| Typical purity specification | 95 percent or higher | Value read from the HPLC chromatogram |
| Storage, dry solid | Minus 20 degrees Celsius, desiccated | Sealed container, protected from light |
| Handling, solution | Divide into single-use portions | Limits losses from freeze-thaw cycling |
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.
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.
Several names circulate for the same molecule, including epitalon, epithalone, epithalamin tetrapeptide, and the sequence code AEDG. A CAS registry number, 307297-39-8, is commonly cited for it, though catalogue entries should be checked against supplier documentation because mislabelled records occur. In its usual form the peptide carries free amino and carboxyl termini and is neither glycosylated nor lipidated. Researchers distinguish the defined tetrapeptide from epithalamin itself, a crude pineal preparation containing many peptides that is not chemically characterised.
Material supplied for laboratory use is normally a lyophilised white to off-white powder that dissolves readily in water and in isotonic saline. Lyophilised cakes are hygroscopic and should be equilibrated to room temperature before opening to limit condensation on the solid. Solutions are typically prepared at milligram-per-millilitre concentrations and divided into single-use aliquots, because repeated freeze–thaw cycles degrade short peptides. Aqueous solutions are far less stable than the dry powder, and identity is usually verified by mass spectrometry alongside purity estimation from reversed-phase high-performance liquid chromatography.
Epitalon is a synthetic linear tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and the calculated mass is approximately 390.35 g/mol. The compound is made by solid-phase peptide synthesis rather than extracted from tissue, although early work described it as a short fragment of a peptide fraction obtained from bovine pineal extract. In the research literature the spelling epitalon and the variant epithalone both appear, while AEDG is the standard code used in peptide nomenclature.
Laboratory handling begins with dissolution of the lyophilized powder in water or a suitable aqueous buffer. The dry solid is the more stable form, so stock solutions are generally prepared only when required and kept cold afterwards. Repeated freezing and thawing of a solution is avoided because it encourages aggregation and gradual loss of the intact chain. Diluents and containers are selected to limit adsorption of a short peptide onto plastic surfaces and to reduce microbial growth in aqueous preparations.
Stability depends strongly on pH, temperature and the presence of oxygen and trace metals. Cleavage of the backbone proceeds faster under neutral to alkaline conditions, whereas acidic solutions tend to slow that reaction. The aspartate and glutamate side chains can undergo deamidation or imide formation over time, generating closely related impurities. Published stability data specific to epitalon are sparse, so the usable life of a given solution is best regarded as an open question that depends on buffer composition, concentration and storage temperature.
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.
3 April The U.S. Department of Defense announced that the death toll for American soldiers in the war had exceeded the 32,629 who had died in the Korean War, based on 312 additional deaths during the week from March 22 to March 28 to bring the toll to 33,641. Laird announced that the U.S. sought to "Vietnamize" the war as quickly as possible but that troop withdrawals would not take place while the PAVN/VC was conducting attacks.
=== Other uses === Ethyl carbamate was primarily an intermediate in the preparation of amino resins, that were in turn used as crosslinking agents for permanent-press textile treatments to create "wash-and-wear" fabrics. Other uses included as solvent or intermediates in the manufacture of pesticides, cosmetics and pharmaceuticals.
This table does not represent an exhaustive list, but demonstrates the various methods this medication is able to be administered. Flupentixol and melitracen is produced by numerous pharmaceutical companies worldwide, with many using oral tablets as the preferred route.
=== February === 1 February Mike Behrens, lawyer and judge, King's Counsel (since 1999), District Court judge (2004–2011) (born 1941). Dame Iritana Tāwhiwhirangi, Māori language advocate (born 1929). 2 February – Peter Babich, Hall of Fame viticulturist and businessman (born 1932). 5 February – Brian Turner, field hockey player (national team), poet and environmental campaigner, Commonwealth Poetry Prize (1999), Poet Laureate (2003–2005) (born 1944). 6 February – Jim Cole, volcanologist (University of Canterbury), Fellow of the Royal Society of New Zealand (since 2004) (born 1941). 7 February – Ian Barton, forester, heritage advocate (Queen's Redoubt Trust), and local-body politician, Franklin District Councillor (1998–2004) (born 1937). 10 February Lynne Giddings, nursing and women's studies academic (Auckland University of Technology, University of Auckland) (born 1945). Toni Huata, Māori musician (born 1969). Rod McElrea, racing driver, national beach racing champion (1971), OSCA champion (1983) (born 1941). 12 February – Theo Janssen, sculptor, stained-glass artist and painter (born 1934). 13 February – Joe Pope, business executive (Petrocorp, ENZA) and rugby administrator, chair of Hurricanes franchise (1999–2003) and Wellington Rugby Football Union (2003–2009) (born 1941). 15 February David Ellison, Māori leader (Kāti Huirapa), veterans' welfare and children's health advocate (born 1936). David Parsons, musician, composer and ethnomusicologist (born 1944). 17 February – David Saunders, lawyer and judge, District Court judge (1993–2020) (born c. 1951).
== Tethelin (Roberson's patent and trade-mark) == In March 1916, Robertson published a suite of five interconnected articles in the Journal of Biological Chemistry, describing the process through which a material, which he called tethelin (from τεθηλώς, 'growing'), he and his assistant, Louis Adolph Ray (1886-1960), had extracted (in 1915) from the anterior lobes of ox pituitaries acquired from a local slaughterhouse (BR.22), and its positive effects on the growth of his experimental mice (BR.23–BR.26). Robertson claimed that the substance was the pituitary's "growth-controlling principle"; and, according to Robertson's account, on-going research demonstrated that tethelin not only controlled growth, but was very effective in the treatment of ulcers of long standing and slow-healing wounds. Prior to the (March 1916) publication of his discoveries, Robertson had not only been granted the US patent (BR.18) and the UK patent (BR.19) for the "Tethelin" extraction process, but had also begun to use the trade-mark TETHELIN, the rights to which he was subsequently granted in December 1916 (BR.21). Well aware of Jokichi Takamine's earlier struggle to patent adrenalin, and the challenges and time delays Takamine experienced, Robertson simply patented his process, and not his product.
Sources: en.wikipedia.org
=== tiv-tiz === tivanidazole (INN) tivantinib (INN) tividenofusp alfa (INN) tividenofusp alfa-eknm tivirapine (INN) tivozanib (USAN, INN) tixadil (INN) tixanox (INN) tixocortol (INN) tizabrin (INN) tizanidine (INN) tizolemide (INN) tizoprolic acid (INN) Tizveni
An overlap syndrome is a medical condition which shares features of at least two more widely recognised disorders. Examples of overlap syndromes can be found in many medical specialties such as overlapping connective tissue disorders in rheumatology, and overlapping genetic disorders in cardiology.
The trend of serum creatinine concentrations over time is more important than the absolute creatinine concentration. Serum creatinine concentrations may increase when an ACE inhibitor (ACEI) is taken for heart failure and chronic kidney disease. ACE inhibitors provide survival benefits for patients with heart failure and slow disease progression in patients with chronic kidney disease. An increase not exceeding 30% is to be expected with use of an ACE inhibitor. Therefore, an ACE inhibitor should not be withdrawn when the serum creatinine increases, unless the increase exceeds 30% or hyperkalemia develops.
Depletion of PPARG in mice results in embryonic lethality at E10.5, due to the vascular anomalies in placenta, with no permeation of fetal blood vessels and dilation and rupture of maternal blood sinuses. The expression of PPARG can be detected in mouse placenta as early as E8.5 and through the remainder of gestation; in the human placenta, PPARG is mainly located in the primary trophoblast cell. PPARG is required for epithelial differentiation of trophoblast tissue in mice, which is critical for proper placenta vascularization. PPARG agonists inhibit extravillous cytotrophoblast invasion. PPARG is also required for the accumulation of lipid droplets by the placenta in mice.
Specific site targeting requires the residues to also be modified to be accessible and chemically bioorthogonal to the rest of the silk protein. Cytosine residues are commonly used for this type of conjugation through a Michael addition, but they tend to undergo exchange reactions which makes them unstable for long durations in a biological environment. These two methods are rather outdated but have been useful in validating the fact that 4RepCT can be tuned in the important areas of cellular adhesion, antimicrobial potency, and the type of molecule or drug attached to it. Later azide functional groups were conjugated to the N-terminal of a dragline silk protein using EDC/NHS coupling, yielding glycopolymer-conjugated films with enhanced cell adhesion and DNA-silk chimeras with controllable micro-architectures. Armed with this, the researchers in this study investigated the incorporation of 3 L-Aha residues into 4RepCT, yielding
Sources: en.wikipedia.org
=== Prediction and analysis of drug targets === RNApred: Prediction of RNA binding proteins from its amino acid sequence. ProPrint: Prediction of interaction between proteins from their amino acid sequence. DomPrint: A domain-domain interaction (DDI) prediction server. MycoPrint: A web interface for exploration of the interactome of Mycobacterium tuberculosis H37Rv (Mtb) predicted by the "Domain Interaction Mapping" (DIM) method. ATPint: A server for predicting ATP interacting residues in proteins. FADpred: Identification of FAD interacting residues in proteins. GTPbinder: Prediction of protein GTP interacting residues. NADbinder: Prediction of NAD binding residues in proteins. PreMier: Software for predicting mannose interacting residues in proteins. DMAP: Designing of mutants of antibacterial peptides. icaars: Prediction and classification of aminoacyl tRNA synthetases using PROSITE domains. CBtope: Prediction of conformational B-cell epitope in a sequence from its amino acid sequence. DesiRM: Designing of Complementary and Mismatch siRNAs for silencing a gene. GenomeABC: A server for benchmarking of genome assemblers.
== Production == The novel was partly inspired by Stephenson's involvement with the Clock of the Long Now project, to which he contributed three pages of sketches and notes. A separate compact disc, entitled IOLET: Music from the World of Anathem, containing eight experimental vocal compositions by David Stutz, was sold separately through CD Baby and the Long Now Foundation, with profits going to The Clock of the Long Now project. To create the world of Arbre, Stephenson constructs new vocabulary. In order to familiarize the reader with the new words, many of which are analogous to English, Latin or Greek words and ideas, a glossary is included at the end of the book. Each chapter begins with a definition of one of these words, which usually relates to the chapter in some way. In addition, the Orth language spoken by the characters was created by Jeremy Bornstein at the author's request, and has been documented. The word anathem was invented by Stephenson, based on the word anthem and the Greek word anathema. In the book, an anathem is a mathic ritual by which one is expelled from the mathic world.
June 6, 2000: Law in favor of equal access for women and men to electoral mandates and elective functions. June 30, 2000: Law concerning compensatory allowance in divorce matters. July 10, 2000: Law concerning the election of senators, with measures regarding gender parity. November 28, 2000: Government amendment lifting the ban on night work for women, against the opinion of the French Communist Party (PCF), which wanted to ban night work for all, except for exemptions. December 23, 2000: Social Security Financing Law for 2001, which includes the creation of a parental presence allowance in case of illness, accident, or disability of the child. May 9, 2001: Law concerning professional equality between women and men. November 16, 2001: Law concerning the fight against discrimination. December 3, 2001: Law concerning the rights of the surviving spouse and illegitimate children, and modernizing various provisions of inheritance law. December 21, 2001: Social Security Financing Act for 2002, which notably includes the establishment of paternity leave. December 21, 2001: Decree establishing a National Commission against Violence towards Women. January 9, 2002: Decree regarding the provision of emergency contraception medication to minors. January 17, 2002: Social Modernization Act, which notably includes elements related to sexual harassment, as well as others concerning discrimination in housing. January 22, 2002: Law concerning access to origins for adopted individuals and wards of the state.
== Pathology == It has been suggested that these cell rests are the histogenetic origins of Brenner tumors, due to the histological similarity of the epithelium of Walthard cell rests and Brenner tumors to the urothelium of the lower urinary tract. Also, it has been proposed that Brenner tumors and Walthard cell rests signify urothelial differentiation within the female genital tract.
Sources: en.wikipedia.org
Reversed-phase high-performance liquid chromatography is run alongside mass spectrometry. The chromatogram separates components and gives a purity figure, while the mass spectrum confirms that the measured molecular mass matches the expected sequence. Neither measurement on its own is treated as sufficient.
Long-term holding is usually at minus twenty degrees Celsius in a sealed, desiccated container. A refrigerator is adequate for short intervals before use. Light exposure is normally avoided as well. Allowing a cold container to warm before opening reduces moisture condensation on the contents.
Repeated cycles are generally avoided. Each freeze and thaw can promote aggregation or loss of peptide to container surfaces, which reduces the amount available for later work. Dividing a solution into single-use portions at the outset is the usual way to limit this problem.
It is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, often abbreviated AEDG. The molecule is linear and contains no modified residues, so it is fully described by its sequence.