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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.
Laboratory-grade epitalon is typically supplied as a lyophilized powder. Purity is commonly assessed with reverse-phase high-performance liquid chromatography, often paired with mass spectrometry to confirm molecular identity. Amino acid analysis and peptide mapping can provide additional confirmation of sequence. Certificates of analysis for research materials frequently report purity above 95 percent, although the methods behind such figures vary between suppliers. The absence of a pharmacopeial monograph means that no single standardized assay defines the compound, so reported results depend on the analytical protocol chosen.
Identity testing for epitalon relies on reversed-phase high-performance liquid chromatography for purity and mass spectrometry for mass confirmation. Because the sequence contains no tryptophan or tyrosine, ultraviolet detection at 280 nanometres is insensitive, so chromatographic methods usually monitor absorbance near 214 nanometres, where the peptide backbone absorbs. Electrospray ionisation or matrix-assisted laser desorption/ionisation then checks the intact mass against the expected value near 390 daltons. Peptide mapping or amino acid analysis after acid hydrolysis can supplement these measurements, although such confirmatory work is seldom reported on commercial certificates of analysis.
Stability of the tetrapeptide follows ordinary peptide chemistry rather than any unusual structural feature. The aspartate-glycine pair is prone to aspartimide formation under mildly basic or neutral conditions, and deamidation can follow, altering both mass and chromatographic retention. Dry lyophilised powder kept at or below minus twenty degrees Celsius is the usual handling recommendation, with repeated freeze-thaw cycles avoided. Once dissolved in neutral aqueous buffer, degradation proceeds over days to weeks depending on pH and temperature, while acidic conditions generally slow the aspartimide route. A formal stability-indicating study has not been published in the indexed literature.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Free acid form of the tetrapeptide |
| Molecular mass | About 390.35 Da | Calculated monoisotopic value |
| Appearance | White to off-white powder | Typical lyophilized presentation |
| Solubility | Soluble in water | Also dissolves in buffered saline |
| Storage temperature | Minus 20 degrees Celsius | Dry, dark conditions; avoid repeated thawing |
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.
The molecule is a short, linear, hydrophilic peptide that dissolves readily in water or aqueous buffer. Its principal chemical liabilities are hydrolytic rather than oxidative, since it contains no cysteine, methionine, or tryptophan residues. The aspartate–glycine step is a recognised site for aspartimide formation under mildly acidic or basic conditions, generating isoaspartate and succinimide-related products over time. Desiccated lyophilised powder held at −20 °C is comparatively stable, whereas dilute solutions degrade faster and are best frozen as single-use aliquots rather than thawed repeatedly.
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.
=== Forms === Spironolactone is available in the form of tablets (25, 50, and 100 mg; brand name Aldactone, others) and suspensions (25 mg/5 mL; brand name Carospir) for oral administration. It had also been marketed in the form of 2 or 5% topical cream in Italy for the treatment of acne and hirsutism under the brand name Spiroderm, but this product is no longer available. The medication is also available in combination with other medications, such as hydrochlorothiazide (brand name Aldactazide, others). Spironolactone has poor water solubility, so only oral and topical formulations have been developed; other routes of administration such as intravenous injection are not used. The only antimineralocorticoid that is available as a solution for parenteral use is the related medication potassium canrenoate.
A Russian S-300 missile hit a museum in Kupiansk, Kharkiv Oblast, killing two people and wounding ten others. Natalia Humeniuk, the spokeswoman for Ukraine's Southern Defense Forces, stated that they had destroyed between 13 and 20 pieces of Russian military equipment on the left (east) bank of the Dnipro River each day over the last three days, and had inflicted heavy losses on the enemy.
== History == Fujirebio was founded in Tokyo, Japan in 1950 under the name Fujizoki Pharmaceutical, Co., Inc. In its early days the company developed and manufactured pharmaceutical products. The company's first IVD test was launched in 1966, a TPHA kit for syphilis testing. In 1983 the company changed name to Fujirebio Inc. Between 1998 and 2010 Fujirebio acquired several specialized IVD companies, notably Centocor Diagnostics (1998), CanAg Diagnostics (2006) and Innogenetics (2010). In 2005, Fujirebio Inc. was integrated together with the commercial laboratories SRL, Inc. ("Special Reference Laboratories", established in 1970) under the holding company Miraca Holdings Inc. (which was renamed to H.U. Group Holdings, Inc. in 2020). The current company structure, Fujirebio Holdings, Inc. was created in 2017 as a parent company of Fujirebio Inc., Fujirebio Diagnostics, Inc., Fujirebio Europe N.V. and other Fujirebio group companies. In 2022, Fujirebio acquired respectively the companies ADx NeuroSciences and Fluxus, Inc. In 2025, Fujirebio acquired Plasma Services Group, Inc.
Sources: en.wikipedia.org
February 9 The second impeachment trial of Donald Trump begins. He is acquitted four days later, February 13 with a 57–43 vote in the Senate, ten votes short of the required two-thirds majority for conviction. COVID-19 drug development: The FDA issues an emergency use authorization (EUA) for bamlanivimab and etesevimab. February 11 President Biden terminates the national emergency declaration on the US-Mexico border which President Trump had used to pay for the wall. In Fort Worth, Texas, at least six people are killed in an accident involving 133 vehicles on Interstate 35W, affected by weather conditions left by a snowstorm system. February 12 The United States Senate votes by unanimous consent to award United States Capitol Police officer Eugene Goodman the Congressional Gold Medal for keeping rioters away from the Senate chamber during the storming of the United States Capitol. The U.S. Food and Drug Administration approves Cosela as the first therapy in its class to reduce the frequency of chemotherapy-induced bone marrow suppression. February 15 – House Speaker Nancy Pelosi announces that Congress will establish a 9/11-styled commission to investigate the January 6 riot at the United States Capitol. February 13–17 – A major winter storm kills 58 people in the United States (and 12 in Mexico) and causes over 9,724,000 power outages across 13 states in the Midwest and Southwest, with Southwest Power Pool declaring an "energy emergency". February 17 COVID-19 pandemic: North Dakota confirms their first case of the UK variant of SARS-CoV-2.
=== Normal–phase chromatography === Normal–phase chromatography was one of the first kinds of HPLC that chemists developed, but has decreased in use over the last decades. Also known as normal-phase HPLC (NP-HPLC), this method separates analytes based on their affinity for a polar stationary surface such as silica; hence it is based on analyte ability to engage in polar interactions (such as hydrogen-bonding or dipole-dipole type of interactions) with the sorbent surface. NP-HPLC uses a non-polar, non-aqueous mobile phase (e.g., chloroform), and works effectively for separating analytes readily soluble in non-polar solvents. The analyte associates with and is retained by the polar stationary phase. Adsorption strengths increase with increased analyte polarity. The interaction strength depends not only on the functional groups present in the structure of the analyte molecule, but also on steric factors. The effect of steric hindrance on interaction strength allows this method to resolve (separate) structural isomers. The use of more polar solvents in the mobile phase will decrease the retention time of analytes, whereas more hydrophobic solvents tend to induce slower elution (increased retention times). Very polar solvents such as traces of water in the mobile phase tend to adsorb to the solid surface of the stationary phase forming a stationary bound (water) layer which is considered to play an active role in retention.
== N-Glycosidic bonds in DNA == DNA molecules contain 5-membered carbon rings called deoxyriboses that are directly attached to two phosphate groups and a nucleobase that contains amino groups. The nitrogen atoms from the amino group in the nucleotides are covalently linked to the anomeric carbon of the ribose sugar structure through an N-glycosidic bond. Occasionally, the nucleobases attached to the ribose undergo deamination, alkylation, or oxidation which results in cytotoxic lesions along the DNA backbone. These modifications severely threaten the cohesiveness of the DNA molecule, leading to the development of diseases such as cancer. DNA glycosylases are enzymes that catalyze the hydrolysis the N-glycosidic bond to free the damaged or modified nucleobase from the DNA, by cleaving the carbon-nitrogen glycosidic bond at the 2' carbon, subsequently initiating the base excision repair (BER) pathway. Monofunctional glycosylases catalyze the hydrolysis of the N-glycosidic bond via either a stepwise, SN1 like mechanism, or a concerted, SN2 like mechanism. The stepwise function, the nucleobase acts as a leaving group before the anomeric carbon gets attacked by the water molecule, producing a short-lived unstable oxacarbenium ion intermediate. This intermediate rapidly reacts with the nearby water molecule to substitute the N-glycosidic bond of the ribose and the nucleobase with an O-glycosidic bond with a hydroxy group. The concerted mechanism, the water acts as a nucleophile and attacks at the anomeric carbon before the nucelobase gets to act like a leaving group.
Sources: en.wikipedia.org
=== General chemical analysis === Freezing-point depression can be used as a purity analysis tool when analysed by differential scanning calorimetry. This is possible because the temperature range over which a mixture of compounds melts is dependent on their relative amounts. Consequently, less pure compounds will exhibit a broadened melting peak that begins at lower temperature than a pure compound.
These are taxonomy (discovering, describing, and naming species), nomenclature (ensuring the correct and universally accepted naming of those species), phylogeny (inferring the evolutionary relationships among species), and classification (arranging species into higher-order groups like genera, families, and orders). These activities are interdependent. For example, naming a new species (an act of taxonomy) automatically places it within a genus, implicitly hypothesizing a relationship to other members of that genus. Likewise, classifications are continually revised as phylogenetic studies uncover more natural (evolutionarily valid) groupings. A guiding principle in modern systematics is to ensure that each recognized group includes all descendants of one common ancestor (a condition called monophyly). Groupings based only on superficial similarity rather than real ancestry are considered artificial; when studies reveal such cases, the groups are reorganized to reflect true evolutionary lineages. In practice this means many traditional lichen groups defined by convenient field characters (such as all "crustose" lichens or all lichens with a certain type of fruiting body) have been dismantled, and their members redistributed, to ensure that each genus or family reflects a single evolutionary lineage. Lichen systematics has been revolutionized in recent decades by molecular biology and genomics. DNA sequencing now allows researchers to resolve cryptic species and deep evolutionary relationships that were impossible to discern from morphology alone.
Neutrino experiments include ICARUS and MicroBooNE, both of which use high-purity liquid argon in a time projection chamber for fine grained three-dimensional imaging of neutrino interactions. At Linköping University, Sweden, the inert gas is being utilized in a vacuum chamber in which plasma is introduced to ionize metallic films. This process results in a film usable for manufacturing computer processors. The new process would eliminate the need for chemical baths and use of expensive, dangerous and rare materials.
== History == The safety and effectiveness of donislecel was evaluated in two non-randomized, single-arm studies in which a total of 30 participants with type 1 diabetes and hypoglycemic unawareness received at least one infusion and a maximum of three infusions. Overall, 21 participants did not need to take insulin for a year or more, with eleven participants not needing insulin for one to five years and ten participants not needing insulin for more than five years. Five participants did not achieve any days of insulin independence. The FDA granted marketing approval of Lantidra to CellTrans, Inc.
Sources: en.wikipedia.org
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.
No naturally occurring free form of the peptide has been described. The four-amino-acid sequence can appear as a fragment within larger proteins, but that is not the same as the intact compound being present as a circulating molecule. Materials used in research are synthetic.
Purity is usually checked by reverse-phase high-performance liquid chromatography, which separates the target peptide from related impurities. Mass spectrometry is commonly used alongside it to confirm molecular mass. Some suppliers also provide amino acid analysis for additional sequence confirmation.
The molecule lacks aromatic residues, so it absorbs weakly near 280 nanometres, the wavelength applied to many other peptides. The peptide bond absorbs strongly below 220 nanometres, making 214 nanometres a practical compromise. Gradient methods must therefore use mobile phases with low ultraviolet absorbance to keep the baseline clean.