The short version of AEDG tetrapeptide fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-04-27. Anything still debated is marked as such rather than presented as settled.
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.
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.
（TG:@pojiaai）Epitalon is a synthetic linear tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, abbreviated AEDG. It emerged from work on epithalamin, a peptide fraction prepared from bovine pineal tissue, and was designed as a short, chemically defined analogue of that extract. Early publications came mainly from Russian laboratories studying pineal peptides and aging-related endpoints. The compound appears in the literature under several spellings, including epithalon and epithalone, which complicates systematic searching. Its small size makes solid-phase assembly and routine analytical characterization straightforward.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Computed for the free acid of Ala-Glu-Asp-Gly |
| Molecular mass | About 390.35 g/mol | Free peptide; salt forms shift the value |
| Appearance | White to off-white solid | Typical of short peptides after freeze-drying |
| Solubility class | Freely soluble in water | Aqueous buffers are also commonly used |
| Common synonyms | Epitalon, epithalone, AEDG | AEDG is the single-letter sequence |
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.
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.
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.
== D == Dendrite A branched projection of a neuron that receives synaptic input from other neurons and transmits electrical signals toward the cell body. Dendritic spine A small, membranous protrusion from a neuron's dendrite that typically receives input from a single synapse of an axon. Spines are key sites for synaptic strength and plasticity. Depolarization A change in membrane potential that makes the interior of a neuron more positive relative to the outside, often initiating an action potential if a threshold is reached. Descending neuron A neuron that originates in the brain or brainstem and projects downward through the spinal cord to influence motor circuits and autonomic function. Descending neurons are critical for voluntary movement, postural control, and reflex modulation. Major descending pathways include the corticospinal, reticulospinal, rubrospinal, and vestibulospinal tracts. Developmental neuroscience A branch of neuroscience focused on how the nervous system develops from embryonic stages through adulthood, including neurogenesis, synaptogenesis, and pruning. Diffusion tensor imaging (DTI) A form of magnetic resonance imaging that maps the diffusion of water molecules in brain tissue to visualize white matter tracts and structural connectivity. Diencephalon A region of the forebrain that includes structures such as the thalamus and hypothalamus. It plays a role in sensory relay, autonomic function, and endocrine regulation.
The enzyme uses molecular oxygen and reduced nicotinamide adenine dinucleotide phosphate (NADPH) to insert a hydroxy group into a specific position in one of the benzene rings of the starting material. It is a cytochrome P450 protein containing heme which acts as an oxidoreductase. The systematic name of this enzyme class is flavonoid,NADPH:oxygen oxidoreductase (3′-hydroxylating). Other names in common use include flavonoid 3′-hydroxylase, flavonoid 3-hydroxylase (erroneous), NADPH:flavonoid-3′-hydroxylase, and flavonoid 3-monooxygenase (erroneous). In palnts including Matthiola incana from which it was first characterised, it is part of the pathway to anthocyanins.
=== DeBakey === The DeBakey system, named after cardiothoracic surgeon Michael E. DeBakey, is an anatomical description of the aortic dissection. It categorizes the dissection based on where the original intimal tear is located and the extent of the dissection (localized to either the ascending aorta or descending aorta or involving both the ascending and descending aorta).
However, others experience the term "borderline personality disorder" as a pejorative label rather than an informative diagnosis. They report concerns that their self-destructive behavior is incorrectly perceived as manipulative and that the stigma surrounding this disorder limits their access to health care.
Sources: en.wikipedia.org
=== Eyelid layers === The eyelid consists of multiple layers, including the skin, subcutaneous tissue, orbicularis oculi muscle, orbital septum, orbital fat, tarsal plate, and conjunctiva. The skin is thin and prone to redundancy with age, while the orbital septum helps contain the orbital fat, which may protrude and contribute to eyelid "bags."
== Diagnosis == Genetic testing for the m.3243A>G mutation in mitochondrial DNA is commonly used to isolate the diagnosis of MELAS syndrome from other mitochondrial disorders. This mutation is an adenine to guanine point mutation at base pair 3,243 in the mitochondrial genome. A minimum amount of mtDNA must be mutated to generate the MELAS phenotype, known as the "threshold effect". Due to mitochondrial heteroplasmy, urine and blood testing is preferable to blood alone. PCR and ARMS-PCR are commonly used, reliable, rapid, and cost-effective techniques for the diagnosis of MELAS. Magnetic-resonance imaging (MRI) is a common imaging test used to identify the presence of stroke-like lesions. These lesions are multifocal infarct-like areas of cortical edema in different stages of ischemic evolution, yet do not commonly conform to any known vascular territory, distinguishing them from a stroke. Initial lesions often occur in the occipital or parietal lobes with eventual involvement of the cerebellum, cerebral cortex, basal ganglia, and thalamus. The occipital lobe is thought to be a region prone to stroke-like lesions due to the high energy requirements of the visual cortex. Lactate levels are often elevated in serum and cerebrospinal fluid. Magnetic resonance spectroscopy (MRS) may show an elevated lactate peak in affected and even unaffected brain areas. Muscle biopsy shows ragged red fibers. However, genetic evaluation should be done first, which eliminates the need for muscle biopsy in most cases. Diagnosis may be molecular or clinical:
On 29 September 1923, the British government became responsible for the administration of Mandatory Palestine. Along with its longstanding control of the Persian Gulf Residency and the Aden Protectorate, and its recently acquired control of the Emirate of Transjordan and of Mandatory Iraq, the British now controlled all of the territories in the Middle East except the French Mandate for Syria and the Lebanon. In 1942, the Biltmore Program was adopted as the platform of the Zionist Organization, with an explicit call "that Palestine be established as a Jewish Commonwealth." In 1946, the Anglo-American Committee of Inquiry, also known as the Grady-Morrison Committee, noted that the demand for a Jewish State went beyond the obligations of either the Balfour Declaration or the Mandate and had been expressly disowned by the Chairman of the Jewish Agency as recently as 1932. The period of the British Mandate was characterized by a great deal of political and social unrest among the Jews, the Palestinian Arabs, and the British (for example, the 1936–1939 Arab revolt, the 1944–1948 Jewish insurgency, and the 1947–1948 civil war in Mandatory Palestine). The United Nations Partition Plan for Palestine was passed on 29 November 1947. The plan was accepted by the Jewish Agency for Palestine but was rejected by the Arab Higher Committee and by most of the Arab population. The Arab League then adopted a series of resolutions endorsing a military solution to the conflict.
== Mechanism of action == Despite its name (ending in -omycin) Fosfomycin is not a macrolide, but a member of a novel class of phosphonic antibiotics. Fosfomycin is bactericidal and inhibits bacterial cell wall biogenesis by inactivating the enzyme UDP-N-acetylglucosamine-3-enolpyruvyltransferase, also known as MurA. This enzyme catalyzes the committed step in peptidoglycan biosynthesis, namely the ligation of phosphoenolpyruvate (PEP) to the 3'-hydroxyl group of UDP-N-acetylglucosamine. This pyruvate moiety provides the linker that bridges the glycan and peptide portion of peptidoglycan. Fosfomycin is a PEP analog that inhibits MurA by alkylating an active site cysteine residue (Cys 115 in the Escherichia coli enzyme). Fosfomycin enters the bacterial cell through the glycerophosphate transporter.
===== United Kingdom ===== In the UK, semaglutide is available on NHS prescription for diabetes at nominal or no cost to the individual. It is also available for obesity, limited to treatment for two years.
Sources: en.wikipedia.org
== Classification == CDPSs can be divided into two distinct subfamilies named NYH and XYP, distinguished depending on the conserved residues within their respective active sites, which let experts predict their aminoacyl-tRNA substrates. Both subfamilies mainly differ in the first half of their Rossmann fold, this two structures correspond to two different structural solutions to facilitate the reactivity of the catalytic serine residue. Some NYH’s crystal structures have been identified. These CDPSs’ structure contain a Rossmann fold domain. NYH form a larger group than XYP, therefore there is more information about them than about the XYP subfamily.
The AAA pathway involves the condensation of α-ketoglutarate and acetyl-CoA via the intermediate AAA for the synthesis of L-lysine. This pathway has been shown to be present in several yeast species, as well as protists and higher fungi. It has also been reported that an alternative variant of the AAA route has been found in Thermus thermophilus and Pyrococcus horikoshii, which could indicate that this pathway is more widely spread in prokaryotes than originally proposed. The first and rate-limiting step in the AAA pathway is the condensation reaction between acetyl-CoA and α‑ketoglutarate catalysed by homocitrate-synthase (HCS) (E.C 2.3.3.14) to give the intermediate homocitryl‑CoA, which is hydrolysed by the same enzyme to produce homocitrate. Homocitrate is enzymatically dehydrated by homoaconitase (HAc) (E.C 4.2.1.36) to yield cis-homoaconitate. HAc then catalyses a second reaction in which cis-homoaconitate undergoes rehydration to produce homoisocitrate. The resulting product undergoes an oxidative decarboxylation by homoisocitrate dehydrogenase (HIDH) (E.C 1.1.1.87) to yield α‑ketoadipate. AAA is then formed via a pyridoxal 5′-phosphate (PLP)-dependent aminotransferase (PLP-AT) (E.C 2.6.1.39), using glutamate as the amino donor. From this point on, the AAA pathway varies with [something is missing here ? -> at the very least, section header! ] on the kingdom.
Ethanol-containing beverages can cause alcohol flush reactions, exacerbations of rhinitis, and, more seriously and commonly, bronchoconstriction in patients with a history of asthma, and in some cases, urticarial skin eruptions, and systemic dermatitis. Such reactions can occur within 1–60 minutes of ethanol ingestion, and may be caused by:
=== Active site === In addition to the Schiff base linkage, PLP is anchored to the active site of the enzyme via hydrogen bonding at the Tyr 207 and Glu237 residues. In addition, the phosphate oxygen atoms on the PLP molecule interact with the Arg99, Val269, Val270, and Thr310 residues. Mammalian BCATs show a unique structural CXXC motif (Cys315 and Cys318) sensitive to oxidizing agents and modulated through S-nitrosation, a post-translational modification that regulates cell signaling. Modification of these two cysteine residues via oxidation (in vivo/vitro) or titration (in vitro) has been found to inhibit enzyme activity, indicating that the CXXC motif is crucial to optimal protein folding and function. The sensitivity of both isoenzymes to oxidation make them potential biomarkers for the redox environment within the cell. Although the CXXC motif is present only in mammalian BCATs, the surrounding amino acid residues were found to be highly conserved in both prokaryotic and eukaryotic cells. Conway, Yeenawar et al. found that the mammalian active site contains three surfaces: surface A (Phe75, Tyr207 and Thr240), surface B (Phe30, Tyr141, and Ala314), and surface C (Tyr70, Leu153 and Val155, located on the opposite domain) that bind to the substrate in a Van der Waals-type interaction with the branched side chains of the amino acid substrates.
Sources: en.wikipedia.org
It is a four-amino-acid peptide with the sequence alanine-glutamate-aspartate-glycine. The chain is unmodified and contains only standard proteinogenic residues, which makes it straightforward to produce by solid-phase synthesis and to characterise by standard peptide methods.
Epitalon and epithalon both circulate, and the difference reflects transliteration of a name coined in Russian-language publications. Reference to the extract it derives from, epithalamin, explains the shared stem. Databases and suppliers are inconsistent, so a search for one spelling alone may miss relevant entries.
No. Epithalamin is a multi-component preparation obtained from pineal tissue, and its exact composition is not fully characterised. Epitalon is a single defined tetrapeptide described as a short synthetic counterpart of that extract, so the two are related in origin but not interchangeable in identity.
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.