tetrapeptide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-08-27. Numbers and descriptions here follow the published literature rather than marketing material.
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.
The proposed relationship between epitalon and pineal function is a central part of its background. Khavinson's group reported that short peptides corresponding to regions of larger pineal proteins could influence gene expression in cells. Epitalon was framed as a synthetic analogue of an active fragment rather than a direct isolation product. Whether the tetrapeptide reproduces the effects of the parent extract is an open question, because comparative studies are limited and the parent extract itself is not a single defined substance.
Interest in epitalon is usually discussed within the broader field of short peptide bioregulators, a category that includes other synthetic di-, tri-, and tetrapeptides studied by the same research group. These compounds share a common rationale: that small fragments of tissue-derived proteins can retain biological activity and can be produced reproducibly. The category as a whole remains outside mainstream pharmacological consensus, and epitalon specifically has a limited presence in independent, non-Russian research literature, which shapes how its evidence base is described.
Epitalon is a synthetic tetrapeptide with the amino acid sequence alanine-glutamate-aspartate-glycine, abbreviated Ala-Glu-Asp-Gly or AEDG. It was developed by the Russian researcher Vladimir Khavinson and colleagues during work on peptide bioregulators derived from the pineal gland. The compound is short enough to be produced by standard solid-phase peptide synthesis and is typically handled as a lyophilized white powder. Its small size distinguishes it from larger pineal peptides such as epithalamin, a complex extract from which the tetrapeptide was conceptually derived.
| Property | Value | Notes |
|---|---|---|
| Amino acid sequence | Ala-Glu-Asp-Gly | Linear tetrapeptide, also written AEDG |
| Molecular mass | About 390.35 g/mol | Value calculated from the sequence |
| Appearance | White to off-white powder | Lyophilised material forms a loose cake |
| Solubility | Freely soluble in water | Also dissolves in isotonic saline |
| Storage | -20 °C, desiccated | Aliquot solutions to avoid freeze–thaw cycling |
Proposed mechanisms centre on cell-culture observations rather than a defined receptor interaction. Several reports describe increased expression of the telomerase catalytic subunit after exposure of cultured human cells, and the authors attributed the effect to short peptide fragments entering the nucleus and influencing gene transcription. No receptor for the tetrapeptide has been identified, and the free peptide is expected to be degraded rapidly by plasma peptidases. Whether any measurable fraction reaches intact tissues after administration remains an unresolved question rather than an established finding.
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 whose sequence is alanine-glutamate-aspartate-glycine, written in single-letter code as AEDG. The four residues are joined by three peptide bonds, giving a linear backbone with no branching and no disulfide bridges. Its calculated molecular mass for the free form is approximately 390.3 daltons, a figure that rises when the compound is supplied as an acetate or trifluoroacetate salt. Because the chain is short, the molecule is defined entirely by its residue order rather than by any folded three-dimensional structure.
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.
Oral ingestion is the most common route of administration of pharmaceuticals. Passing through the esophagus to the stomach, the contents of the capsule or tablet are absorbed by the GI tract. The absorbed pharmaceutical is then passed through the liver and kidneys. The rate of dissolution is a key target for controlling the duration of a drug's effect, and as such, several dosage forms that contain the same active ingredient may be available, differing only in the rate of dissolution. If a drug is supplied in a form that is not readily dissolved, it may be released gradually and act for longer. Having a longer duration of action may improve compliance since the medication will not have to be taken as often. Additionally, slow-release dosage forms may maintain concentrations within an acceptable therapeutic range over a longer period, whereas quick-release dosage forms may have sharper peaks and troughs in serum concentration. The rate of dissolution is described by the Noyes–Whitney equation as shown below: d W d t = D A ( C s − C ) L
The most common application of cervical drug delivery is for treatment of cervical cancer. Due to the direct route provided through the use of cervical drug delivery mechanisms, it proves to be the most effective route with the lowest number of side effects. The localized treatment has been suggested as ideal as cancer is treated with highly toxic compounds, such as chemotherapeutics. The more contained the exposure to these compounds can be, the less negative impacts the patient will endure. Treatment can be delivered in the form of nanoparticles, vaginal gels, or films and reach the cervix quickly for ideal response. Vaginal gels are easily administered into the vaginal canal to reach the cervix due to low viscosity at room temperature. When inserted into the body which has a higher temperature, the gels become more viscous, allowing them to reside longer at the cervix and have more sustained release. Vaginal films are very thin films inserted into the vagina to release a compound. They can be maintained for six hours in cervical mucus, meaning they hold potential to treat cervical cancer caused by Human Papilloma Virus. Nanoparticle systems take advantage of the size of nanoparticles to encapsulate the drugs and pass through the mucus barrier.
CPC offers direct scale-up from analytical apparatuses (few milliliters) to industrial apparatuses (several liters) for fast batch-production. CPC seems particularly suited to accommodate aqueous two-phase solvent systems. Generally, CPC instruments can retain solvent systems that are not well-retained in a hydrodynamic instrument due to small differences in density between the phases. It has been very helpful for the development of CPC instrumentation to visualize the flow patterns which give rise to the mixing and settling in the CPC chamber with an asynchronous camera and a stroboscope triggered by the CPC rotor. The aforementioned hydrodynamic and hydrostatic instruments may be employed in a variety of ways, or modes of operation, in order to address the particular separation needs of the scientist. Many modes of operation have been devised to take advantage of the strengths and potentialities of the countercurrent chromatography technique. Generally, the following modes may be performed with commercially available instruments.
Andexanet alfa is a biologic agent, a recombinant modified version of human activated factor X (FXa). Andexanet alfa differs from native FXa due to the removal of a 34 residue fragment that contains the Gla domain. This modification reduces andexanet alfa's anticoagulant potential. Additionally, a serine to alanine (S419A) mutation in the active site eliminates its activity as a prothrombin to thrombin catalyst, but still allows the molecule to bind to FXa inhibitors. FXa inhibitors bind to andexanet alfa with the same affinity as to natural FXa. As a consequence, in the presence of andexanet alfa, natural FXa is partially freed, which can lead to effective hemostasis. In other words, it acts as a decoy receptor. Andexanet alfa reverses effect of all anticoagulants that act directly through FXa or by binding antithrombin III. The drug is not effective against factor IIa inhibitor dabigatran. Its activity is measured using the anti-Xa test, which is utilized to determine the amount of available factor Xa for coagulation
A simple supersecondary protein topology composed of two or more consecutive antiparallel β-strands linked together by hairpin loops. This motif is common in β-sheets and can be found in several structural architectures including β-barrels and β-propellers. The vast majority of β-meander regions in proteins are found packed against other motifs or sections of the polypeptide chain, forming portions of the hydrophobic core that canonically drives formation of the folded structure. However, several notable exceptions include the Outer Surface Protein A (OspA) variants and the Single Layer β-sheet Proteins (SLBPs) which contain single-layer β-sheets in the absence of a traditional hydrophobic core. These β-rich proteins feature an extended single-layer β-meander β-sheets that are primarily stabilized via inter-β-strand interactions and hydrophobic interactions present in the turn regions connecting individual strands.
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This term has become very popular and commonly used in practice. But the appropriate expression is "enantioselective chromatography". Chiral chromatography has advanced to turn into the most preferred technique for the determination of enantiomeric purity as well as separation of pure enantiomers both on analytical and preparative scale. Chiral chromatographic assay is the first step in any study pertaining to enantioselective synthesis or separation. This includes the use of techniques viz. gas chromatography (GC), high performance liquid chromatography (HPLC), chiral supercritical fluid chromatography (SFC), capillary electrophoresis (CE) and thin-layer chromatography (TLC). The result of a literature survey done identifies HPLC-based chiral assays as the most dominating technology in use. An overview of various analytical methods engaged for chiral separation and analysis are listed in the table.
A variety of natural and synthetic inhibitors of ATP synthase have been discovered. These have been used to probe the structure and mechanism of ATP synthase. Some may be of therapeutic use. There are several classes of ATP synthase inhibitors, including peptide inhibitors, polyphenolic phytochemicals, polyketides, organotin compounds, polyenic α-pyrone derivatives, cationic inhibitors, substrate analogs, amino acid modifiers, and other miscellaneous chemicals. Some of the most commonly used ATP synthase inhibitors are oligomycin and DCCD. E. coli ATP synthase is the simplest known form of ATP synthase, with 8 different subunit types. Bacterial F-ATPases can occasionally operate in reverse, turning them into an ATPase. Some bacteria have no F-ATPase, using an A/V-type ATPase bidirectionally. Yeast ATP synthase is one of the best-studied eukaryotic ATP synthases; and five F1, eight FO subunits, and seven associated proteins have been identified. Most of these proteins have homologues in other eukaryotes.
While juxtaposed against free-radical polymerization, the application of automated synthesis can be utilized for controlled radical polymerization too. These methods have been used within reversible addition-fragmentation transfer (RAFT), atom-transfer radical (ATRP), and nitroxide-mediated polymerizations, demonstrating the ability of robots to improve efficiency and reduce the hardship of performing reactions. For example, with the automatic dispensation of reagents, Symyx Technologies Inc. was able to polymerize styrene and butyl acrylate through ATRP. In addition, this functionality was supported by Zhang et al. within their research, finding that reproducibility and comparability were equivalent to classical ATRP.
The urine test may be a chromatographic immunoassay or any of several other test formats, home-, physician's office-, or laboratory-based. Published detection thresholds range from 20 to 100 mIU/mL, depending on the brand of test. Early in pregnancy, more accurate results may be obtained by using the first urine of the morning (when urine is most concentrated). When the urine is dilute (specific gravity less than 1.015), the hCG concentration may not be representative of the blood concentration, and the test may be falsely negative. The serum test, using 2-4 mL of venous blood, is typically a chemiluminescent or fluorimetric immunoassay that can detect βhCG levels as low as 5 mIU/mL and allows quantification of the βhCG concentration. The hCG levels grow exponentially after conception and implantation. hCG levels typically peak around weeks 8-11 of pregnancy and are generally higher in the first trimester compared to the second trimester. The following is a list of serum hCG levels: LMP is the last menstrual period dated from the first day of the last menstrual period
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Signal transduction is realized by activation of specific receptors and consequent production/delivery of second messengers, such as Ca2+ or cAMP. These molecules operate as signal transducers, triggering intracellular cascades and in turn amplifying the initial signal. Two main signal transduction mechanisms have been identified, via nuclear receptors, or via transmembrane receptors. In the first one, first messenger cross through the cell membrane, binding and activating intracellular receptors localized at nucleus or cytosol, which then act as transcriptional factors regulating directly gene expression. This is possible due to the lipophilic nature of those ligands, mainly hormones. In the signal transduction via transmembrane receptors, the first messenger binds to the extracellular domain of transmembrane receptor, activating it. These receptors may have intrinsic catalytic activity or may be coupled to effector enzymes, or may also be associated to ionic channels. Therefore, there are four main transmembrane receptor types: G protein coupled receptors (GPCRs), tyrosine kinase receptors (RTKs), serine/threonine kinase receptors (RSTKs), and ligand-gated ion channels (LGICs). Second messengers can be classified into three classes:
Different genotypes may compete with each other in a way that is not beneficial for the population. A pure line optimized for a certain environment or usage outperforms the CCP under these specific conditions. There is no reason to believe that the Darwinian selection will work in the desired direction for traits such as baking quality. Natural selection and in-field human selection act on the plant stage, not the seed stage. Common Bunt is a seed borne disease in wheat. In conventional farming it is controlled by fungicide treatment of seeds. In organic farming seeds can be cleaned by brushing before sowing, but it is also desirable that plants have genetic resistance. A CCP, including crosses of resistant cultivars, was grown with heavy common bunt infection for 5 years and it appeared to get more resistant, but the common bunt's virulence appeared to change at least as fast. The overall result was that infection levels went up.
Reticulocytes are newly produced red blood cells. They are slightly larger than totally mature red blood cells, and have some residual ribosomal RNA. The presence of RNA allows a visible blue stain to bind or, in the case of fluorescent dye, result in a different brightness. This allows them to be detected and counted as a distinct population. The RPI is used to assess whether the bone marrow is producing an appropriate response to an anemic state. Reticulocyte production should increase in response to any loss of red blood cells. It should increase within 2–3 days of a major acute hemorrhage, for instance, and reach its peak in 6–10 days. If reticulocyte production is not raised in response to anemia, then the anemia may be due to an acute cause with insufficient time to compensate, or there is a defect with red blood cell production in the bone marrow. Marrow defects include nutritional deficiencies (i.e. iron, folate, or B12) or insufficient erythropoietin, the stimulus for red blood cell production. Reticulocytopenia, or "aplastic crisis", is the medical term for an abnormal decrease of reticulocytes in the body The reticulocyte production index may find new use as a more reliable detector of erythropoietin-doping in athletes. The use of this method is referred to as "biological passport."
Sources: en.wikipedia.org
It is a synthetic tetrapeptide. Its sequence was derived from research on peptide fractions of bovine pineal extract, and the intact AEDG sequence has not been demonstrated as an abundant free peptide in human tissue.
AEDG is the one-letter code for the four amino acids alanine, glutamate, aspartate and glycine in that order. The same molecule is written in three-letter form as Ala-Glu-Asp-Gly.
Identity is normally confirmed by mass spectrometry against the calculated mass of roughly 390.35 g/mol. Purity is then estimated by reversed-phase high-performance liquid chromatography with ultraviolet detection.
Epitalon is a synthetic tetrapeptide composed of four amino acids: alanine, glutamate, aspartate, and glycine. It is written as Ala-Glu-Asp-Gly. The free peptide has a molecular weight of about 390 daltons and is normally supplied as a lyophilized powder.