If you have been reading about Tetrapeptide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-04-18. Numbers and descriptions here follow the published literature rather than marketing material.
The compound is described in the literature as a derivative of epithalamin, a preparation obtained from bovine pineal tissue. Work on this peptide family was carried out mainly by a research group in Saint Petersburg beginning in the 1980s, and the substance was later registered for clinical use in Russia under the name Epitalon. Outside that region it is generally treated as a research chemical rather than an approved medicine. Statements about its biological activity rest on a relatively small number of studies, and independent replication remains limited.
In its supplied form epitalon is a white to off-white powder, usually lyophilized and often hygroscopic. It dissolves readily in water and in aqueous buffers, and it is commonly handled as the acetate or trifluoroacetate salt to improve stability during purification and drying. The amide backbone is labile in aqueous media, so solutions are less durable than the dry solid. Handling notes in the chemical literature therefore emphasize keeping the powder dry, cool and shielded from light until it is dissolved.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic tetrapeptide | Four residues, linear chain |
| Residue sequence | Ala-Glu-Asp-Gly | Single-letter form AEDG |
| Calculated mass | 390.3 daltons | Value for the free, uncharged form |
| Appearance | White to off-white powder | Usually supplied lyophilized |
| Solubility | Freely soluble in water | Often handled as a salt form |
（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.
L-cystathionine + H2O = L-cysteine + 2-oxobutanoate + NH3 (overall reaction) (1a) L-cystathionine = L-cysteine + 2-aminobut-2-enoate (1b) 2-aminobut-2-enoate = 2-iminobutanoate (spontaneous) (1c) 2-iminobutanoate + H2O = 2-oxobutanoate + NH3 (spontaneous) Pyridoxal phosphate is a prosthetic group of this enzyme. Cystathionine γ-lyase also catalyses the following elimination reactions:
Half-Life: Echoes is a modification of the first-person shooter video game Half-Life created by British developer James "MrGnang" Coburn and released on August 10, 2018. The mod was under development for four years and uses the GoldSrc engine. Echoes is from the perspective of an unnamed scientist from the Black Mesa Research Facility as the resonance cascade happens and has the player fight unused monsters and the HECU with the G-Man and "Kingpin" observing the player.
In addition, estradiol levels with estradiol patches are higher in the evening than in the morning, which may be due to circadian variations in skin blood flow that may influence absorption. In terms of area-under-the-curve levels of estradiol, the interindividual variability of transdermal estradiol has been found to be 20 to 44% using different transdermal formulations, and the intraindividual variability with transdermal estradiol has been found to be 20%. Factors which may contribute to inter- and intraindividual variability with transdermal estradiol include skin location and thickness; hair follicle density; solvent (alcohol) evaporation; skin dehydration, ambient temperature, and humidity; and reservoir size.
== Bibliography == Claret, Jaume; Santirso, Manuel (2014). La construcción del catalanismo. Historia de un afán político (in Spanish). Madrid: Los Libros de la Catarata. ISBN 978-84-8319-898-8. García de Cortázar, Fernando; González Vesga, José Manuel (2012). Breve historia de España (in Spanish) (6º ed.). Madrid: Alianza Editorial. ISBN 978-84-206-7374-5. Juliá, Santos (1999). Un siglo de España. Política y sociedad (in Spanish). Madrid: Marcial Pons. ISBN 84-9537903-1. Powell, Charles (2002) [2001]. España en democracia, 1975-2000 (in Spanish). Barcelona: Plaza & Janés. ISBN 84-9759-022-8. Preston, Paul (2003). Juan Carlos. El rey de un pueblo (in Spanish). Barcelona: Plaza & Janés. ISBN 84-01-37824-9. Ruiz, David (2002). La España democrática (1975-2000). Política y sociedad (in Spanish). Madrid: Síntesis. ISBN 84-9756-015-9. Sánchez-Cuenca, Ignacio (2012). Años de cambios, años de crisis. Ocho años de gobiernos socialistas, 2004-2011 (in Spanish). Madrid: Los Libros de la Catarata-Fundación Alternativas. ISBN 978-84-8319-682-3. Sánchez-Cuenca, Ignacio (2014). La impotencia democrática. Sobre la crisis política de España (in Spanish). Madrid: Los Libros de la Catarata. ISBN 978-84-8319-881-0. Tusell, Javier (1997). La transición española. La recuperación de las libertades (in Spanish). Madrid: Historia 16-Temas de Hoy. ISBN 84-7679-327-8.
The slide is left to air dry, after which the blood is fixed to the slide by immersing it briefly in methanol. The fixative is essential for good staining and presentation of cellular detail. After fixation, the slide is stained to distinguish the cells from each other. Routine analysis of blood in medical laboratories is usually performed on blood films stained with Romanowsky stains such as Wright's stain, Giemsa stain, or Diff-Quik. Wright-Giemsa combination stain is also a popular choice. These stains allow for the detection of white blood cell, red blood cell, and platelet abnormalities. Hematopathologists often use other specialized stains to aid in the differential diagnosis of blood disorders. After staining, the monolayer is viewed under a microscope using magnification up to 1000 times. Individual cells are examined and their morphology is characterized and recorded.
Sources: en.wikipedia.org
The NHS questioned the benefits of the medication for depression and claimed that it was too expensive. People already using esketamine were allowed to complete treatment if their doctors considered this necessary. Esketamine is approved in the United States for and shows promise as a rapid-acting monotherapy for treatment-resistant depression, but evidence is currently limited to a single trial. It is an effective and generally safe long-term treatment for adults with treatment-resistant depression, feasible in outpatient settings; optimal oral antidepressant combinations and predictive biomarkers need further research. Spravato debuted at a cost of treatment of US$32,400 per year when it launched in the United States in March 2019. The Institute for Clinical and Economic Review (ICER), which evaluates cost effectiveness of drugs analogously to the National Institute for Health and Care Excellence (NICE) in the United Kingdom, declined to recommend esketamine for depression due to its steep cost and modest efficacy, deeming it not sufficiently cost-effective. Esketamine is the second drug to be approved for treatment-resistant depression by the FDA, following olanzapine/fluoxetine (Symbyax) in 2009. Other agents, like the atypical antipsychotics aripiprazole (Abilify) and quetiapine (Seroquel), have been approved for use in the adjunctive therapy of major depressive disorder in people with a partial response to treatment.
Cancers are found to attract and rely on immune suppressors such as regulatory T cells or other cells in the tumor microenvironment to decrease the response of immune cells. Further, reducing the activity of cytotoxic T cells by sustaining expression of inhibitory receptors limits the effectiveness of immune checkpoint inhibitors. Cancers can modify the tumor microenvironment itself, creating physical and biochemical barriers to immune attack. Abnormal vasculature is a prominent way of doing this. Tumors secrete factors that attract the growth of blood vessels (angiogenesis) that encourages further methods of nutrient transport, feeding the tumor. Additionally, cancer cells can produce nerve growth factor which causes healthy neurons to develop around and within tumors. This is promotes further tumor growth because nerves produce neurotransmitters 5HT that prompt tumor cell proliferation. Essentially solid tumors are able to create networks of feedback loops, hijacking healthy cells.
Construction materials The chambers are generally built of brick masonry, or hollow cement-concrete slabs. Sheet metal or prefabricated aluminium in a double-walled construction with sandwiched thermal insulation, such as glass wool or polyurethane foams, are materials that are also used in some modern timber ovens. However, brick masonry chambers, with lime and (mortar) plaster on the inside and painted with impermeable coatings, are used widely and have been found to be satisfactory for many applications. Heating Heating is usually carried out by steam heat exchangers and pipes of various configurations (e.g. plain, or finned (transverse or longitudinal) tubes) or by large flue pipes through which hot gases from a wood-burning furnace are passed. Only occasionally is electricity or gas employed for heating. Humidification Humidification is commonly accomplished by introducing live steam into the kiln through a steam spray pipe. In order to limit and control the humidity of the air when large quantities of moisture are being rapidly evaporated from the timber, there is normally a provision for ventilation of the chamber in all types of kilns. Air circulation Air circulation is the means for carrying the heat to and the moisture away from all parts of a load. Forced circulation kilns are most common, where the air is circulated by means of fans or blowers, which may be installed outside the kiln chamber (external fan kiln) or inside it (internal fan kiln).
The degree of strictness of border controls varies across countries and borders. In some countries, controls may be targeted at the traveller's religion, ethnicity, nationality, or countries visited. Others may need to ensure the traveller has paid the appropriate fees for their visas and has future travel planned outside the country. Yet others may concentrate on the contents of the traveller's baggage and imported goods to ensure nothing is being carried that might pose a biosecurity risk to the country.
Sources: en.wikipedia.org
The peptide contains four residues in the order alanine, glutamate, aspartate and glycine, abbreviated AEDG. The chain is linear and held together by three peptide bonds. Its calculated mass for the uncharged free form is about 390.3 daltons.
Epithalamin refers to a crude preparation derived from bovine pineal tissue, which contains many components. Epitalon is a single synthetic tetrapeptide identified from that material and produced by chemical synthesis. The two names are sometimes confused because early reports treated the synthetic peptide as an active fragment of the extract.
It has been registered for clinical use in Russia, where it is associated with a small family of short peptides. In most other jurisdictions it is not an approved medicine and is traded as a research chemical. Regulatory status varies by country and changes over time.
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.