Khavinson raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-01-15. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic tetrapeptide | Four amino acid residues |
| Residue sequence | Ala-Glu-Asp-Gly | Abbreviated AEDG |
| Approximate mass | 390.35 Da | Monoisotopic, free base form |
| Parent preparation | Epithalamin extract | Derived from pineal tissue |
| Common spelling variants | Epithalon, epithalone, AEDG | Affects literature retrieval |
The published literature is dominated by a small number of research groups, much of it in Russian-language journals, and independent replication outside those groups is limited. Studies are typically small, use cultured cells or rodent models, and report endpoints that differ between papers, which makes comparison difficult. Large randomised human trials have not appeared in the indexed literature. Questions about absorption, distribution and clearance are therefore still treated as open in reviews that mention the compound.
Epitalon is a synthetic tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. Its design traces to epithalamin, a peptide fraction prepared from bovine pineal gland extracts that researchers in Saint Petersburg began investigating in the 1970s. The compound has a molecular formula of C14H22N4O9 and a nominal molecular mass near 390 daltons. It holds no approved drug status in the United States or the European Union, and material sold under this name is generally offered as a research chemical rather than a finished pharmaceutical product.
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.
Transferred components are immune cells and autologous as above. Transfer of immune cells is made between different individuals of monozygotic twins in human or of the same pure line in experimental animals from immunologically sensitized to naive host, where transferred cells are engrafted without rejection or GVHD in the new host. Transfer of cells are made between allogeneic hosts but the new host is irradiated for preventing rejection or GVHD. Transfer of cells are made between allogeneic hosts. Transferred components include cells as well as immune molecules such as immunoglobulins between allogeneic hosts. The term is used almost synonymously for "passive immunity" in some situations, however, passive immunity acts among xenogeneic hosts; for example, in snake venom immunotherapy, antivenom IgG is obtained from sensitized horse and inoculated to humans. The following terms might indicate procedures involving similar immunological transfer processes. adoptive transfer adoptive immunization adoptive immunotherapy Adoptive cell therapy adoptive tolerance
GLD-2 is a common and abundant, but yet quite unknown protein that has already been found in each of the five kingdoms. In the animal kingdom, it has been specially detected in Homo sapiens, Drosophila, Xenopus and Mus musculus. However, there has also been noticed the presence of GLD-2 in Arabidopsis thaliana which belongs in the plants kingdom; Escherichia Coli in monera and Candida albicans in fungi. In human beings it is mostly expressed in the brain and within it, in the cerebellum, hippocampus and medulla. They can also be found in other source tissues such as the fibroblast, HeLa cell, MCF-7 cell, melanoma cell line and thymus. Inside those cells, it can be located in the nucleus and mitochondrion since its main function is related with DNA polyadenilation and these cell organelles are the only ones were DNA can be found. However, there are also GLD-2 in a soluble way in the cytosol; the reason for their presence is still unsure. In Escherichia Coli, this enzymatic protein can be found in the cell membrane and in the cytosol, whereas in Drosophila melanogaster, it predominates in the brain's nucleus and cytoplasm, oocyte, ovary and testis’ cells. Finally, in the Arabidopsis thaliana, it is located in the flower's nucleus, root, stem and leaf cells.
== External links == Actinium at The Periodic Table of Videos (University of Nottingham) NLM Hazardous Substances Databank – Actinium, Radioactive Actinium in Kirby, H. W.; Morss, L. R. (2006). Morss; Edelstein, Norman M.; Fuger, Jean (eds.). The Chemistry of the Actinide and Transactinide Elements (3rd ed.). Dordrecht, The Netherlands: Springer. ISBN 978-1-4020-3555-5.
Thiazolidinediones (TZDs), also known as "glitazones," bind to PPARγ, peroxisome proliferator activated receptor γ, a type of nuclear regulatory protein involved in the transcription of genes that regulate glucose and fat metabolism. These PPARs act on peroxisome proliferator responsive elements (PPRE). The PPREs influence insulin-sensitive genes, which enhance production of mRNAs of insulin-dependent enzymes. The final result is better use of glucose by the cells. These drugs also enhance PPAR-α activity and hence lead to a rise in HDL and some larger components of LDL. Typical reductions in glycated hemoglobin (A1C) values are 1.5–2.0%. Some examples are:
Sources: en.wikipedia.org
==== Advantages ==== Increase efficacy and therapeutic index of drug and stability via encapsulation Non-toxic, flexible, biocompatible, completely biodegradable, and non-immunogenic for systemic and non-systemic administrations Reduce toxicity of the encapsulated agent (amphotericin B, Taxol) Reduce the exposure of sensitive tissues to toxic drugs, site avoidance effect and flexibility to couple with site-specific ligands to achieve active targeting
Like most gouramis, the croaking gourami is susceptible to diseases and infections (for instance, very cold air temperatures at the water surface may lead to infections of the labyrinth organ), so regular water changes and temperature maintenance (both in and above the tank) are a must. This species is tolerant of fairly high temperatures: temperatures of 29 °C (84 °F) are easily tolerated though 26 °C (79 °F) seems to be close to optimal. A pH of 6.8 is about right and peat filtration is recommended. Furthermore, this species is very sensitive to noise, so the tank should be in a quiet area.
2023 North Sea incident: Two cargo ships, the British-flagged Verity and the Bahamas-flagged Polesie, collide in the North Sea near the Heligoland islands, with several individuals missing and the suspected sinking of the Verity. 25 October Lloyds Banking Group releases forecasts for UK house prices, predicting they will shrink by 4.7% in 2023 and 2.4% in 2024, before beginning to rise again in 2025. Sunak tells Parliament he supports "specific pauses" in the Israel–Hamas conflict to allow the delivery of aid and get British citizens out of the area. Lewis Edwards, a former officer with South Wales Police who groomed 210 underage girls using social media and blackmailed them into sending him indecent photographs, is sentenced to life imprisonment with a minimum term of 12 years. Three members of the Just Stop Oil protest group are arrested on suspicion of criminal damage after spraying the Wellington Arch in central London with orange paint. A police misconduct hearing finds that two Metropolitan Police officers who stopped and searched athletes Bianca Williams and Ricardo Dos Santos in west London committed gross misconduct, and the officers are dismissed. 26 October – Sunak gives a speech warning of the dangers of artificial intelligence. 27 October Labour Mayor of London Sadiq Khan, Mayor of Greater Manchester Andy Burnham, and Scottish Labour leader Anas Sarwar break with the stance of Labour's leader, Sir Keir Starmer, on the Israel–Hamas conflict by calling for a ceasefire in Gaza.
=== Proteogenomics === In proteogenomics, proteomic technologies such as mass spectrometry are used for improving gene annotations. Parallel analysis of the genome and the proteome facilitates discovery of post-translational modifications and proteolytic events, especially when comparing multiple species (comparative proteogenomics).
=== Non-inhibitory roles === Non-inhibitory extracellular serpins also perform a wide array of important roles. Thyroxine-binding globulin and transcortin transport the hormones thyroxine and cortisol, respectively. The non-inhibitory serpin ovalbumin is the most abundant protein in egg white. Its exact function is unknown, but it is thought to be a storage protein for the developing foetus. Heat shock serpin 47 is a chaperone, essential for proper folding of collagen. It acts by stabilising collagen's triple helix whilst it is being processed in the endoplasmic reticulum. Some serpins are both protease inhibitors and perform additional roles. For example, the nuclear cysteine protease inhibitor MENT, in birds also acts as a chromatin remodelling molecule in a bird's red blood cells.
Sources: en.wikipedia.org
Glomerular filtration of unbound drug. Active secretion of (free & protein-bound) drug by transporters (e.g. anions such as urate, penicillin, glucuronide, sulfate conjugates) or cations such as choline, histamine. Filtrate 100-fold concentrated in tubules for a favorable concentration gradient so that it may be secreted by passive diffusion and passed out through the urine.
Due to the potential for widespread usage and the evolving needs of researchers, many different mutants of GFP have been engineered. The first major improvement was a single point mutation (S65T) reported in 1995 in Nature by Roger Tsien. This mutation dramatically improved the spectral characteristics of GFP, resulting in increased fluorescence, photostability, and a shift of the major excitation peak to 488 nm, with the peak emission kept at 509 nm. This matched the spectral characteristics of commonly available FITC filter sets, increasing the practicality of use by the general researcher. A 37 °C folding efficiency (F64L) point mutant to this scaffold, yielding enhanced GFP (EGFP), was discovered in 1995 by the laboratories of Thastrup and Falkow. EGFP allowed the practical use of GFPs in mammalian cells. EGFP has an extinction coefficient (denoted ε) of 55,000 M−1cm−1. The fluorescence quantum yield (QY) of EGFP is 0.60. The relative brightness, expressed as ε•QY, is 33,000 M−1cm−1. The widely used EGFP sequence, however, may produce an unintended protein product, using the +2 frame as the template. Superfolder GFP (sfGFP), a series of mutations that allow GFP to rapidly fold and mature even when fused to poorly folding peptides, was reported in 2006. Many other mutations have been made, including color mutants; in particular, blue fluorescent protein (EBFP, EBFP2, Azurite, mKalama1), cyan fluorescent protein (ECFP, Cerulean, CyPet, mTurquoise2), and yellow fluorescent protein derivatives (YFP, Citrine, Venus, YPet).
== Synthesis == The biosynthesis of monoglycosylceramides requires a direct transfer of the carbohydrate moiety from a sugar-nucleotide, such as uridine 5-diphosphate(UDP)-galactose, or UDP-glucose to the ceramide unit. The glycosyl-transferase catalyzed reaction results in an inversion of the glycosidic bond stereochemistry, changing from α →β. Synthesis of galactosylceramide, and glucosylceramide occurs on the lumenal surface of the endoplasmic reticulum, and on the cytosolic side of the early Golgi membranes respectively.
== Role in disease == Activation of prothrombin is crucial in physiological and pathological coagulation. Various rare diseases involving prothrombin have been described (e.g., hypoprothrombinemia). Anti-prothrombin antibodies in autoimmune disease may be a factor in the formation of the lupus anticoagulant (also known as antiphospholipid syndrome). Hyperprothrombinemia can be caused by the G20210A mutation. Thrombin, a potent vasoconstrictor and mitogen, is implicated as a major factor in vasospasm following subarachnoid hemorrhage. Blood from a ruptured cerebral aneurysm clots around a cerebral artery, releasing thrombin. This can induce an acute and prolonged narrowing of the blood vessel, potentially resulting in cerebral ischemia and infarction (stroke). Beyond its key role in the dynamic process of thrombus formation, thrombin has a pronounced pro-inflammatory character, which may influence the onset and progression of atherosclerosis. Acting via its specific cell membrane receptors (protease activated receptors: PAR-1, PAR-3 and PAR-4), which are abundantly expressed in all arterial vessel wall constituents, thrombin has the potential to exert pro-atherogenic actions such as inflammation, leukocyte recruitment into the atherosclerotic plaque, enhanced oxidative stress, migration and proliferation of vascular smooth muscle cells, apoptosis and angiogenesis. Thrombin is implicated in the physiology of blood clots. Its presence indicates the existence of a clot. In 2013 a system for detecting the presence of thrombin was developed in mice.
Higher flow rate for same volume size Laboratory scale example: 250 mL centrifugal partition chromatography has optimal flow rate of 5–15 mL/min, 250 mL countercurrent chromatography has optimal flow rate of 1–3 mL/min. Process scale example: 25 L countercurrent chromatography has optimal flow rate of 100–300 ml/min, 25 L centrifugal partition chromatography has optimal flow rate of 1000–3000 ml/min. Higher productivity (due to higher flow rate and faster separation time) Scalable up to tonnes per month Better stationary phase retention for most phases Disadvantages of centrifugal partition chromatography:
Sources: en.wikipedia.org
It is based on epithalamin, a peptide-rich preparation obtained from pineal gland tissue and studied in the former Soviet Union. Researchers later identified the tetrapeptide AEDG as a constituent fragment of that material. Modern supplies are produced by chemical synthesis rather than tissue extraction.
No. Epithalamin is a heterogeneous extract containing many peptides, while epitalon is a single synthesised tetrapeptide. Publications sometimes treat findings from the two as equivalent, which is a common source of confusion. Their compositions differ and they are not interchangeable in analytical terms.
Most published work uses cell cultures or rodents because those models are faster and less costly to run. The few human trials that have been reported are small, and several lack control groups or blinding. This restricts what can reasonably be concluded about effects in people.
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.