Reversed-phase HPLC is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2025-11-06. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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 |
|---|---|---|
| Amino acid sequence | Ala-Glu-Asp-Gly | Tetrapeptide, often abbreviated AEDG |
| Molecular formula | C14H22N4O9 | Free peptide, unmodified termini |
| Molecular weight | ~390.35 Da | Calculated for the free acid form |
| Appearance | White to off-white powder | Typical lyophilized product form |
| Solubility class | Freely soluble in water | Two acidic residues dominate ionic character |
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.
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.
Laboratory handling begins with dissolution of the lyophilized powder in water or a suitable aqueous buffer. The dry solid is the more stable form, so stock solutions are generally prepared only when required and kept cold afterwards. Repeated freezing and thawing of a solution is avoided because it encourages aggregation and gradual loss of the intact chain. Diluents and containers are selected to limit adsorption of a short peptide onto plastic surfaces and to reduce microbial growth in aqueous preparations.
Stability depends strongly on pH, temperature and the presence of oxygen and trace metals. Cleavage of the backbone proceeds faster under neutral to alkaline conditions, whereas acidic solutions tend to slow that reaction. The aspartate and glutamate side chains can undergo deamidation or imide formation over time, generating closely related impurities. Published stability data specific to epitalon are sparse, so the usable life of a given solution is best regarded as an open question that depends on buffer composition, concentration and storage temperature.
=== History === Nitro cold brew was first offered at third wave coffee shops in the early 2010s, but the exact origin is disputed. It may have originated in 2013 at the craft coffee houses Cuvee Coffee in Austin, Texas, and Stumptown in Portland, Oregon. The draft coffee at the Queens Kickshaw in New York in 2011 may be a predecessor. Cuvee Coffee first offered nitro cold brew, on tap, at the Slow Food Quiz Bowl in Austin, Texas, on August 14, 2012. The Ball Corporation issued a press release citing Cuvee as the first company to can cold brew in their widget cans, and BevNet awarded Cuvee the Best Packaging Innovation, calling them "the first cold brew brand to market a nitrogenated offering." Stumptown and Cuvee began offering canned beverages with a nitrogen-filled capsule to pressurize the can by 2015. Starbucks introduced the beverage at 500 stores in the summer of 2016, preceded in the Los Angeles market by The Coffee Bean & Tea Leaf. By 2020, Starbucks offered the beverage at more than half of its locations across the United States, making it a staple menu item. Nitro cold brew is available from wholesalers in some markets in kegs. RISE Brewing Co. says it can fill up to 1,500 kegs a day of nitro cold brew coffee.
pasta bread cookies snacks (chips, nachos) smoothies Cricket flour can be utilized as a complete replacement for flour. The taste is described as very nutty, and foods normally prepared with wheat flour may cook differently.
These events, along with the relationship between Mandela and Pienaar, were the subject of a 2008 book by John Carlin, Playing the Enemy: Nelson Mandela and the Game that Made a Nation, that spotlights the role of the 1995 Cup win in post-apartheid South Africa. Carlin sold the film rights to Morgan Freeman. The result was the 2009 film Invictus, directed by Clint Eastwood and starring Freeman as Nelson Mandela and Matt Damon as Pienaar.
Sources: en.wikipedia.org
On the 20th anniversary in November 2024, Valve made Half-Life 2 temporarily free on Steam and updated it to incorporate Episode One, Episode Two and Lost Coast, improve graphics and controls, restore lost content, fix bugs and add developer commentary. Half-Life 2 reached a new peak of 64,085 concurrent players on Steam, surpassing the previous record of 16,101 in August 2021. Valve also released a two-hour making-of documentary.
Fibronectin type III domain-containing protein 5, the precursor of irisin, is a type I transmembrane glycoprotein that is encoded by the FNDC5 gene. Irisin is a cleaved version of FNDC5, named after the Greek messenger goddess Iris. Fibronectin domain-containing protein 5 is a membrane protein comprising a short cytoplasmic domain, a transmembrane segment, and an ectodomain consisting of a ~100 kDa fibronectin type III (FNIII) domain.
=== Series of coups d'état === On 10 February 1988, Rocky Malebane-Metsing of the People's Progressive Party (PPP) became the president of Bophuthatswana for one day when he took over the government through a military coup. He accused Mangope of corruption and charged that the recent election had been rigged in the government's favour. A statement by the defence force said "serious and disturbing matters of great concern" had emerged, citing Mangope's close association with a multimillionaire Israeli Soviet émigré Shabtai Kalmanovich. Subsequently, the South African Defence Force invaded Bophuthatswana and Mangope was reinstated and continued his term unabated. P. W. Botha, State President of South Africa at the time, justified the reinstatement by saying that "[t]he South African Government is opposed in principle to the obtaining or maintaining of power by violence." In 1990, a second coup attempt took place in which an estimated 50,000 protesters demanded the President's resignation over his handling of the economy. The New York Times reported that seven people had been killed and 450 wounded "after police officers in armoured cars fired their rifles into the crowds and used tear gas and rubber bullets". After Mangope had asked for help from the South African government, he declared a state of emergency and cut telephone links to the territory "for political reasons", claiming that "normal laws had become inadequate". Human Rights Watch put the number of protesters at 150,000.
Sources: en.wikipedia.org
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.
No. Epitalon is chemically synthesized, not extracted. It was designed as a short synthetic fragment conceptually related to larger pineal peptides studied in the same research tradition, particularly the extract known as epithalamin. The two are distinct materials with different compositions.
The term bioregulator is used in this research tradition for short peptides proposed to influence gene expression or cell function. Epitalon is grouped with other synthetic short peptides under this label. The term reflects a proposed mechanism rather than an established drug classification.
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.