HPLC purity raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-01-02. Anything still debated is marked as such rather than presented as settled.
（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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Linear tetrapeptide | Four residues joined by three peptide bonds |
| Sequence | Ala-Glu-Asp-Gly | Commonly abbreviated AEDG |
| Molecular formula | C14H22N4O9 | Free acid form |
| Monoisotopic mass | Approximately 390 Da | Matches values reported from mass spectrometry |
| Net charge near neutral pH | Negative | Contributed by glutamate and aspartate side chains |
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.
The four residues give epitalon a molecular formula of C14H22N4O9 and a molecular weight near 390.35 daltons. The presence of two acidic residues, glutamate and aspartate, makes the free peptide strongly acidic, while the alanine and glycine ends provide neutral, nonpolar character. This combination produces a molecule with substantial water solubility. Because there are no cysteine, methionine, or tryptophan residues, the peptide lacks the most common oxidation-sensitive side chains, which simplifies handling compared with many longer peptides.
Epitalon is a synthetic four-amino-acid peptide with the sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its molecular formula is C14H22N4O9, and its calculated molar mass is approximately 390.35 grams per mole. The compound is a short fragment related to a peptide fraction isolated from bovine pineal gland extracts, and it is normally supplied as a lyophilised powder intended for laboratory research. It is not a registered pharmaceutical product in most countries.
The peptide emerged from research carried out in Saint Petersburg from the late 1980s onward, where investigators searched for shorter active fragments of a pineal preparation known as epithalamin. The name epitalon was chosen to reflect that parent extract. Early reports described effects on neuroendocrine markers and on the lifespan of laboratory animals. Much of that work appeared in Russian-language journals, with English translations following later, which affects how readily the original protocols can be assessed by outside groups.
Endotracheal intubation may be required if the airway is unstable or hypoxia persists when breathing 100% oxygen. Needle decompression or tube thoracostomy may be necessary to drain a pneumothorax or haemothorax Foley catheterization may be necessary for spinal cord AGE if the person is unable to urinate. Intravenous hydration may be required to maintain adequate blood pressure. Therapeutic recompression is indicated for severe AGE. The diving medical practitioner will need to know the vital signs and relevant symptoms, along with the recent pressure exposure and breathing gas history of the patient. Air transport should be below 1,000 feet (300 m) if possible, or in a pressurized aircraft which should be pressurised to as low an altitude as reasonably possible. Sinus squeeze and middle ear squeeze are generally treated with decongestants to reduce the pressure differential, with anti-inflammatory medications to treat the pain. For severe pain, narcotic analgesics may be appropriate. Suit, helmet and mask squeeze are treated as trauma according to symptoms and severity.
=== KLOC === A computer programming expression, the K-LOC or KLOC, pronounced kay-lok, standing for "kilo-lines of code", i.e., thousand lines of code. The unit was used, especially by IBM managers, to express the amount of work required to develop a piece of software. Given that estimates of 20 lines of functional code per day per programmer were often used, it is apparent that 1 K-LOC could take one programmer as long as 50 working days, or 10 working weeks. This measure is no longer in widespread use because different computer languages require different numbers of lines to achieve the same result (occasionally the measure "assembly equivalent lines of code" is used, with appropriate conversion factors from the language actually used to assembly language). Error rates in programming are also measured in "Errors per K-LOC", which is called the defect density. NASA's SATC is one of the few organizations to claim zero defects in a large (>500K-LOC) project, for the space shuttle software. An alternative measurement was defined by Pegasus Mail author David Harris: the "WaP" is equivalent to 71,500 lines of program code, because that number of lines is the length of one edition of Leo Tolstoy's War and Peace.
=== European action === PFOA contaminated waste was incorporated into soil improver and spread on agricultural land in Germany, leading to PFOA drinking water contamination of up to 0.519 parts per billion. The German Federal Environmental Agency issued guidelines for the sum of PFOA and PFOS concentrations in drinking water: 0.1 parts per billion for precaution and 0.3 parts per billion for a threshold. Residents were found to have a 6–8 factor increase of PFOA serum levels over unexposed Germans, with average PFOA concentrations in the 22–27 parts per billion range. An expert panel concluded that "concentrations were considered too low to cause overt adverse health effects in the exposed population". In the Netherlands, after questions by members of Parliament, the minister of Environment ordered a study into the potential exposure to PFOA of people living in the vicinity of the DuPont factory in Dordrecht. The report was published in March 2016 and concluded that "prior to 2002 residents were exposed to levels of PFOA at which health effects could not be ruled out". As a result of this, the government commissioned several further studies, including blood tests and measurements in drinking water. PFOA was identified as a PBT substance in the EU in 2013. It was then included in the candidate list of substances of very high concern. In 2017, PFOA, its salts and PFOA-related substances were added to annex XVII (restriction) of the REACH Regulation.
Sources: en.wikipedia.org
=== 2014–2015: AFL Tribunal hearing against players === After Essendon's Federal Court challenge was dismissed in October 2014 (but while Hird's was still ongoing), ASADA issued fresh show-cause notices to the players on 17 October 2014. The players had two weeks to respond to the notices and exercised their right not to respond. On 13 November 2014, the Anti-Doping Rule Violation Panel concluded that sufficient evidence existed against the players, and they were placed on the register of findings. The following day, the AFL issued infraction notices to the players. The players faced a closed hearing of the AFL Tribunal over several sessions between December 2014 and February 2015. The burden of proof fell to ASADA, and the required standard of proof to return a guilty verdict was "comfortable satisfaction". Upon issuing of the infractions notices on 14 November, players could accept provisional suspensions, meaning they would be ineligible to play AFL-sanctioned matches until the Tribunal hearing was finalised, but that they could continue to train in the pre-season, and that time served during the provisional suspension would be counted as part of any final suspension.
== Diagnosis == Buried bumper syndrome may be suspected based on features consistent with this disorder. The diagnosis is confirmed either endoscopically (via upper endoscopy) or with computed tomography. Upper endoscopy may reveal overgrowth of stomach tissue over the internal bumper (incomplete buried bumper syndrome). If the bumper has eroded deep into the gastric mucosa, it may not be visualized during endoscopic evaluation (complete buried bumper syndrome).
== Trade == South Korea spent around $129 million in 2017 to purchase 275,000 metric tons of foreign kimchi, more than 11 times the amount it exported, according to data released by the Korea Customs Service in 2017. South Korea consumes 1.85 million metric tons of kimchi annually, or 36.1 kg per person. It imports a significant fraction of that, mostly from China, and runs a $47.3 million kimchi trade deficit.
Sources: en.wikipedia.org
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.
The compound came out of work on epithalamin, a peptide preparation derived from pineal tissue, conducted largely in Russian laboratories. Later studies in other countries examined it mainly in cell cultures and animal models.
The tetrapeptide sequence is a synthetic construct rather than a described circulating peptide. It was derived by analogy to peptide fractions obtained from tissue extracts, not isolated from blood or tissue as such.
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.