Replicative senescence is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-03-15. Where a claim depends on a specific study, the study is described rather than over-claimed.
Identity and purity are checked by reversed-phase high-performance liquid chromatography, usually with ultraviolet detection near 214 nanometres, where the peptide bond absorbs. Mass spectrometry confirms the expected mass and reveals whether truncation products or adducts are present. Acid hydrolysis followed by amino acid analysis gives the residue ratio, which should approximate one alanine, one glutamate, one aspartate and one glycine. Counter-ions such as acetate or trifluoroacetate remain in the dried product and lower net peptide content, so a stated purity figure on a label does not by itself describe how much peptide a vial holds.
Regulatory treatment differs by country. No formulation of epitalon holds a marketing authorisation as a medicine in the United States or the European Union, where material sold for laboratory use is handled as a research chemical and is not intended for human consumption. In Russia, several short peptide preparations from the same institute's peptide series are registered medicinal products, and epitalon appears in that national context. Elsewhere it is frequently offered as a cosmetic ingredient, a category with lighter requirements. Advertising claims about longevity or disease prevention are restricted in most jurisdictions, which limits how sellers describe the compound.
Storage recommendations center on limiting moisture, heat, and light. The dry powder is generally kept at minus 20 degrees Celsius, and some suppliers recommend minus 80 degrees for long-term archival. Once dissolved, solutions are usually aliquoted and frozen to avoid repeated freeze-thaw cycles, which can promote aggregation or degradation. Aqueous stability depends on pH and concentration, and buffered saline is often preferred over plain water for biological work. Stability data specific to epitalon remain limited, so general peptide-handling practices are applied by analogy rather than from product-specific validation.
Epitalon is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and its calculated monoisotopic mass is approximately 390.35 daltons. The compound does not occur naturally as a free peptide; it is produced by solid-phase peptide synthesis. Because it contains two acidic residues and no basic residues, the neutral form carries a net negative charge at physiological pH. This charge profile influences how the peptide behaves in solution and during chromatographic analysis.
| Property | Value | Notes |
|---|---|---|
| Storage temperature, solid | Approximately -20 C | Sealed, desiccated, protected from light |
| Typical identity method | Electrospray mass spectrometry | Protonated ion expected near 391 |
| Typical purity method | Reversed-phase HPLC | Ultraviolet detection near 214 nm |
| Common synonyms | Epithalon, epithalone, AEDG | Spelling variants appear in supplier catalogues |
| Solution stability | Days at 2-8 C | Hydrolysis and deamidation limit shelf life |
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 peptide is a synthetic analogue of epithalamin, a preparation extracted from bovine pineal glands. Investigators sought a short, chemically defined molecule that would reproduce some of the endocrine and gerontological observations attributed to the glandular extract. Proposed mechanisms centre on induction of telomerase activity, an effect reported in cultured human somatic cells in the early 2000s, together with influences on melatonin secretion and neuroendocrine regulation. Those mechanisms remain incompletely characterised, and the reported telomerase response has not been consistently reproduced by independent groups working in comparable systems.
Published work on this compound consists mainly of in vitro experiments, animal studies, and small clinical investigations, a substantial share of which appeared in Russian-language journals. Sample sizes are generally small, control conditions differ between studies, and several endpoints rely on markers whose clinical meaning is itself debated. Reviews of the longevity field treat the peptide as an early example of telomerase-directed research rather than an established intervention. Regulatory treatment varies by country: some jurisdictions place it under prescription controls, others treat it as a laboratory material, and importation may be restricted regardless of local status.
Epitalon is a synthetic tetrapeptide whose sequence is alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. It was developed in Russia during the 1980s and 1990s by investigators associated with the St. Petersburg Institute of Bioregulation and Gerontology, who studied short peptides as regulators of gene expression and tissue function. The alternative spelling epithalon appears interchangeably in the literature, and the two names refer to the same molecule. Outside Russia it is encountered chiefly as a research chemical rather than a licensed medicine, and it holds no approval from the United States Food and Drug Administration or the European Medicines Agency.
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.
== Introduction == Theoretical calculation for the proton and neutron drip lines show that there would be about 7,000 nuclides that are between the drip lines, and containing 2 to 120 protons. There are presently 251 known stable nuclides. Many of these in theory could decay through spontaneous fission, alpha decay, double beta decay, etc. with a very long half-life, but this has not yet been observed. Thus, the number of stable nuclides is subject to change if some of these 251 have radioactive decay observed in the future. In this article, the "stable" nuclides are divided into three tables: one for nuclides that are theoretically stable (meaning no decay mode is possible) except to spontaneous fission, which is not considered plausible in this mass range; one for nuclides that can theoretically undergo forms of decay other than spontaneous fission but have no published lower bound on lifetime from experimental evaluations; and one for nuclides that can theoretically decay and have been examined without detecting any decay, allowing a lower bound to be published. In this last table, where a decay has been predicted theoretically but never observed experimentally (either directly or by finding an excess of the daughter), the theoretical decay mode is given in parentheses, and "> (lifetime in years)" is shown in the half-life column to show this lower limit in scientific notation. Such nuclides are considered to be "stable", also called "observationally stable" indicating the tentative nature of the conclusion, until some decay has been observed.
Many of the medications used in feminizing hormone therapy, such as estradiol, cyproterone acetate, and bicalutamide, are substrates of CYP3A4 and other cytochrome P450 enzymes. As a result, inducers of CYP3A4 and other cytochrome P450 enzymes, such as carbamazepine, phenobarbital, phenytoin, rifampin, rifampicin, and St. John's wort, among others, may decrease circulating levels of these medications and thereby decrease their effects. Conversely, inhibitors of CYP3A4 and other cytochrome P450 enzymes, such as cimetidine, clotrimazole, grapefruit juice, itraconazole, ketoconazole, and ritonavir, among others, may increase circulating levels of these medications and thereby increase their effects. The concomitant use of a cytochrome P450 inducer or inhibitor with feminizing hormone therapy may necessitate medication dosage adjustments.
Bromley forms part of the Bromley and Biggin Hill Parliament constituency. The current MP is Peter Fortune. Thomas Turrell is the London Assembly member for the Bexley and Bromley constituency, in which the town is located. This post was previously held by Fortune. Bromley's most prominent MP was the former Conservative prime minister, Harold Macmillan. Bromley is part of the Bromley Town ward for elections to Bromley London Borough Council.
=== Pregnancy === Pregnancy can cause major complications when trying to properly dose the nutrient mixture. Because all of the fetus' nourishment comes from the mother's blood stream, the doctor must properly calculate the dosage of nutrients to meet both recipients' needs and have them in usable forms. Incorrect dosage can lead to many adverse, hard-to-guess effects, such as death, and varying degrees of deformation or other developmental problems. It is recommended that parenteral nutrition administration begins after a period of natural nutrition so doctors can properly calculate the nutritional needs of the fetus. Otherwise, it should only be administered by a team of highly skilled doctors who can accurately assess the fetus' needs.
On 26 November 2018, the mayor of Moscow, Sergey Sobyanin, participated in the ceremony to launch the cable car above the Moskva River. This car connects the Luzhniki sports complex with Sparrow Hills and Kosygin Street. The trip from the viewpoint on Vorobyovy Gory to Luzhniki Stadium takes only five minutes, rather than 20 minutes by car.
Sources: en.wikipedia.org
=== Genome === The genome of Pseudomonas aeruginosa consists of a relatively large circular chromosome (5.5–6.8 Mb) that carries between 5,500 and 6,000 open reading frames, and sometimes plasmids of various sizes depending on the strain. Comparison of 389 genomes from different P. aeruginosa strains showed that just 17.5% is shared. This part of the genome is the P. aeruginosa core genome.
Stream power, originally derived by R. A. Bagnold in the 1960s, is the amount of energy the water in a river or stream is exerting on the sides and bottom of the river. Stream power is the result of multiplying the density of the water, the acceleration of the water due to gravity, the volume of water flowing through the river, and the slope of that water. There are many forms of the stream power formula with varying utilities, such as comparing rivers of various widths or quantifying the energy required to move sediment of a certain size. Stream power is closely related to other criteria such as stream competency and shear stress. Stream power is a valuable measurement for hydrologists and geomorphologists tackling sediment transport issues as well as for civil engineers, who use it in the planning and construction of roads, bridges, dams, and culverts.
As the evidence for most types of alternative medicine such as acupuncture is far from strong, the use of alternative medicine in regular healthcare can present an ethical question. Using the principles of evidence-based medicine to research acupuncture is controversial, and has produced different results. Some research suggests acupuncture can alleviate pain but the majority of research suggests that acupuncture's effects are mainly due to placebo. Evidence suggests that any benefits of acupuncture are short-lasting. There is insufficient evidence to support use of acupuncture compared to mainstream medical treatments. Acupuncture is not better than mainstream treatment in the long term. The use of acupuncture has been criticized owing to there being little scientific evidence for explicit effects, or the mechanisms for its supposed effectiveness, for any condition that is discernible from placebo. Acupuncture has been called "theatrical placebo", and David Gorski argues that when acupuncture proponents advocate "harnessing of placebo effects" or work on developing "meaningful placebos", they essentially concede it is little more than that. Medical doctors practicing acupuncture cannot agree upon the positions of acupuncture points, to the extent it has become meaningless to call them "points".
Although the ancient Egyptians did not always distinguish frankincense from other resins such as myrrh, references to incense from the land of Punt have been dated to the third millennium BCE. Incense trees being transported for cultivation in Thebes are depicted in the so-called "Punt Colonnade" at the mortuary temple of Hatshepsut. The Ebers Papyrus, from around 1500 BCE, provides some of the earliest evidence for frankincense used with intent as a possible therapy. The incense offering occupied a prominent position in the sacrificial legislation of the ancient Hebrews. The Book of Exodus (30:34–38) prescribes frankincense, blended with equal amounts of three aromatic spices, to be ground and burnt in the sacred altar before the Ark of the Covenant in the wilderness Tabernacle, where it was meant to be a holy offering—not to be enjoyed for its fragrance. The Book of Jeremiah (6:20) relates that frankincense was imported from Sheba during the 6th century BC Babylonian captivity. Frankincense is mentioned in the New Testament as one of the three gifts (with gold and myrrh) that the magi "from the East" presented to the Christ Child (Matthew 2:11).
== Cause == Gambierdiscus toxicus is the primary dinoflagellate responsible for the production of a number of similar polyether toxins, including ciguatoxins, maitotoxin and possibly palytoxin. Other dinoflagellates that may cause ciguatera include other Gambierdiscus species and members of the genera Fukuyoa and Ostreopsis.
Sources: en.wikipedia.org
== Vaccine candidates == As of 2023 no vaccine had been licensed, although many had been evaluated in pre-clinical studies. Vaccine candidates have been suggested. Aspartate-β-semialdehyde dehydrogenase (asd) gene deletion mutants are auxotrophic for diaminopimelate (DAP) in rich media and auxotrophic for DAP, lysine, methionine and threonine in minimal media. The Δasd bacterium (bacterium with the asd gene removed) protects against inhalational melioidosis in mice.
In the ovarian follicle, activin increases FSH binding and FSH-induced aromatization. It participates in androgen synthesis enhancing LH action in the ovary and testis. In the male, activin enhances spermatogenesis. Activin is strongly expressed in wounded skin, and overexpression of activin in epidermis of transgenic mice improves wound healing and enhances scar formation. Its action in wound repair and skin morphogenesis is through stimulation of keratinocytes and stromal cells in a dose-dependent manner. Activin also regulates the morphogenesis of branching organs such as the prostate, lung, and especially kidney. Activin A increased the expression level of type-I collagen suggesting that activin A acts as a potent activator of fibroblasts. Lack of activin during development results in neural developmental defects. Upregulation of Activin A drives pluripotent stem cells into a mesoendodermal fate, and thus provides a useful tool for stem cell differentiation and organoid formation.
In the mid-1960s, Owsley Stanley, the most important black market LSD manufacturer in the United States, distributed LSD at a standard concentration of 270 μg, while street samples of the 1970s contained 30 to 300 μg. By the 1980s, the amount had reduced to between 100 and 125 μg, dropping more in the 1990s to the 20 to 80 μg range, and even further in the 2000s.
== Notable research == From 1994 to the present the Siuzdak lab has been working on activity metabolomics. using liquid chromatography mass spectrometry-based metabolomics to identify metabolites that alter phenotype. His initial efforts with Richard Lerner, used liquid chromatography mass spectrometry to perform metabolomic experiments on the cerebral spinal fluid of sleep deprived animals. cis-9,10-octadecenoamide, a novel lipid hormone (also known as oleamide), was observed and shown to have sleep inducing properties. This work is one of the earliest such experiments combining liquid chromatography mass spectrometry and metabolomics to identify active metabolites. Another notable activity metabolomics effort with Oscar Yanes (Spain) identified neuroprotectin D1 as a metabolite that promotes stem cell differentiation. In 1996 whole virus analysis was performed with an electrospray ionization mass spectrometer where the virus was collected and successfully tested for viability. Later, he and his collaborators provided the first example of a whole intact virus (tobacco mosaic virus) being mass measured using a charge detection mass spectrometer, an instrument designed by Henry Benner and Stephen Fuerstenau at Lawrence Berkeley National Labs. In 1999, the Siuzdak lab described the use of nanostructures to enhance desorption/ionization on porous silicon of small molecules (DIOS), this is also known as the first surface-based example of surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS).
Sources: en.wikipedia.org
The solid is kept cold, dry and dark, typically at minus twenty degrees Celsius, in a sealed container with desiccant. Dissolved material is kept refrigerated and used promptly. Freezing and thawing a solution repeatedly is avoided because it accelerates degradation.
Reversed-phase chromatography with ultraviolet detection gives a purity percentage, while mass spectrometry confirms identity. Amino acid analysis checks the residue composition. Buyers typically request a certificate of analysis showing these measurements for the specific lot.
It is not authorised as a medicine in the United States or the European Union. Material is sold there as a research chemical or cosmetic ingredient. Some related short peptides are registered drugs in Russia, which is a distinct national situation rather than a general approval.
Epitalon is a synthetic tetrapeptide built from four amino acids: alanine, glutamate, aspartate, and glycine. It is not extracted from a natural source but made in the laboratory by chemical synthesis. Its short length makes it relatively straightforward to produce at high purity.