reversed-phase HPLC 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.
Last reviewed on 2026-02-15. Where a claim depends on a specific study, the study is described rather than over-claimed.
Residue composition is the property that most cleanly separates verified material from mislabelled samples. Alanine, glutamate, aspartate and glycine appear in that order from the N-terminus, and the two acidic residues sit in the middle of the chain. Because the peptide is short, it can be produced by solid-phase synthesis and characterised by mass spectrometry without ambiguity. Any reported sample whose measured mass departs substantially from 390 daltons is a different compound or a degraded mixture rather than epitalon.
Epitalon is a synthetic tetrapeptide whose four residues are alanine, glutamate, aspartate and glycine, commonly abbreviated AEDG. Its molecular formula is C14H22N4O9 and its monoisotopic mass is near 390.35 daltons. The peptide carries two acidic side chains, so it is neutral to negatively charged in most aqueous buffers. Published reference summaries usually list it under both spellings, epitalon and epithalon, and treat the two names as the same material.
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.
Verification of a sample usually begins with reversed-phase high-performance liquid chromatography, which resolves the peptide from truncated sequences and other impurities and expresses purity as a percentage of total peak area. Mass spectrometry by electrospray ionisation or matrix-assisted laser desorption supplies an independent check, because the measured mass can be compared against the theoretical value for AEDG. Amino acid analysis or tandem mass spectrometry sequencing can confirm residue order. Each of these methods answers a different question: a purity figure does not establish identity, and an identity match does not establish how much of the material is intact peptide.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Derived from the four constituent residues |
| Molecular mass | About 390.35 Da | Monoisotopic value, confirmed by mass spectrometry |
| Residue sequence | Ala-Glu-Asp-Gly | Read from the N-terminus to the C-terminus |
| Common synonyms | Epithalon; AEDG | Both forms appear in reference catalogues |
| Net charge near neutral pH | Negative | Two acidic side chains give a low isoelectric point |
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.
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.
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.
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.
Published studies on epitalon are dominated by a small number of research groups, and independent replication in other laboratories remains limited. Proposed mechanisms include activation of telomerase and modulation of melatonin rhythms, but the evidence for either rests mainly on cell cultures and animal models. Whether the peptide produces comparable effects in humans is an open question, and the absence of large controlled trials means the literature is best read as exploratory rather than settled.
Typical storage for the lyophilized powder is −20 °C or lower, in a sealed container protected from light and moisture. Hygroscopic material should be allowed to equilibrate to room temperature before the vial is opened, which limits condensation on the contents. Working solutions are commonly divided into single-use aliquots and frozen to avoid repeated freeze-thaw cycles. Dilute solutions are more prone to adsorption onto plastic surfaces and to loss during filtration, so procedures that minimize transfers and use low-binding labware are preferable.
Reversed-phase high-performance liquid chromatography is the standard approach for assessing purity, usually with ultraviolet detection near 214 nm, where the peptide bond absorbs. Mass spectrometry, most often with electrospray ionization, confirms the molecular mass and helps reveal truncation or deletion byproducts. Amino acid analysis can verify composition, and counterion content is sometimes measured because peptides purified with trifluoroacetic acid retain variable amounts of that salt. Purity figures reported without a stated method and detection wavelength are difficult to interpret.
=== Violence === The heightened levels of violence and abuse that transgender people experience result in unique adverse effects on bodily and mental health. Specifically, in resource-constrained settings where non-discriminatory policies may be limited or not enforced, transgender people may encounter high rates of stigma and violence which are associated with poor health outcomes. Studies in countries of the Global North show higher levels of discrimination and harassment in school, workplace, healthcare services and the family when compared with cisgender populations, situating transphobia as a key health risk factor for the physical and mental health of transgender people. Victimization is often the outcome to disclosure for transgender individuals. Transgender individuals are pressured to conform to gender norms which make them vulnerable for victimization by peers and parents. A study done by Grossman and D'Augelli reported that transgender youth feared that may face physical and sexual violence because of their experience with harassment and discrimination. The youth also express how individuals only see them for their gender and sexuality rather than their personal traits. Many of the youth have also dropped out or experience academic decline because of the constant harassment. Victimization started on average for transgender at the age of 13, while physical abuse started at an average age 14.
The Morgan State University Band Program consists of six ensembles: the marching band, symphonic band, symphonic winds, pep band, jazz ensemble, and jazz combo. Titled the Magnificent Marching Machine, the marching band has performed at Morgan State football games, NFL games, Presidential Inaugurations, World Series games and in regional and local television appearances. On November 28, 2019, the Magnificent Marching Machine performed during Macy's Thanksgiving Day Parade in New York City. They also performed at the 80th Anniversary and Commemoration of D-Day in Normandy, France on June 12, 2024.
== Available forms == The abuse-deterring effects of atropine when used as an adulterant are reasonably effective in reducing the combination's potential for recreational use. It combines the mechanisms of naloxone and paracetamol (the two more commonly used abuse-deterring agents) by increasing the likelihood of the overdose resulting in harmful and/or fatal sequelae (as does paracetamol), in addition to reliably producing unpleasant side-effects which "spoil" the opioid euphoria and discourage abusers from overdosing again following their initial experience (as does naloxone). This does not deter the use of single doses of difenoxin to potentiate another opiate, the anticholingeric activity of a single tablet is actually likely to increase the pleasurable effects of opioid use in a manner similar to combining one or more opioids with orphenadrine.
Benzodiazepines developed in the former Soviet Union (e.g. phenazepam, gidazepam etc.) Benzodiazepines predominantly used only in Japan (e.g. nimetazepam, flutoprazepam etc.) 4,5-cyclised benzodiazepines (e.g. ketazolam, cloxazolam etc.), and other compounds not researched by Roche Benzodiazepines developed more recently (e.g. remimazolam, QH-ii-066, Ro48-6791 etc.) "Designer" benzodiazepines for which in vitro binding data are unavailable (e.g. flubromazolam, pyrazolam etc.) While binding or activity data are available for most of these compounds also, the assay conditions vary between sources, meaning that in many cases the values are not suitable for a direct comparison. Many older sources used animal measures of activity (i.e. sedation or anticonvulsant activity) but did not measure in vitro binding to benzodiazepine receptors. See for instance Table 2 vs Table 11 in the Chem Rev paper, Table 2 lists in vitro pIC50 values matching those below, while Table 11 has pEC50 values derived from in vivo assays in mice, which show the same activity trends but cannot be compared directly, and includes data for compounds such as diclazepam and flubromazepam which are not available in the main data set. Also note;
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Sources: en.wikipedia.org
The chemical nature of the stationary phase. The stationary phase can be coated with some ligands at different bonding densities (how many ligands are bonded per surface area). The composition of the mobile phase. The mobile phase may be made of one solvent, or a mixture of several solvents. The solvents can be mixed at different ratios. Different mobile phases have different properties, such as polarity. When a mobile phase consists of mostly one solvent, with some other solvents added in small amounts, those other solvents are called "mobile phase modifiers". The pH of the mobile phase, which affect the ionization state of the solutes and their polarity. This can be changed with additives such as buffers. Usually, the stationary phase is made of a layer of hydrophobic substrate bonded to the surface of porous silica gel particles. The particles come in various shapes (spheric, irregular), at different diameters (sub-2, 3, 5, 7, 10 μm), with varying pore diameters (60, 100, 150, 300 Å). The particle diameters are often given as mesh numbers. For example, 2500-mesh corresponds to a particle diameter of 5 μm. The hydrophobic substrates are generally alkyl chains, such as C3, C4, C8, C18, or more. The longer the chain, the longer the sample components will be retained. It would make the resolution power higher, but also make the chromatography take longer to run. Most current methods of separation of biomedical materials use C18 columns, sometimes called by trade names, such as ODS (octadecylsilane) or RP-18 (reverse phase 18).
The number of hydrogen bonds formed by a molecule of liquid water fluctuates with time and temperature. From TIP4P liquid water simulations at 25 °C, it was estimated that each water molecule participates in an average of 3.59 hydrogen bonds. At 100 °C, this number decreases to 3.24 due to the increased molecular motion and decreased density, while at 0 °C, the average number of hydrogen bonds increases to 3.69. Another study found a much smaller number of hydrogen bonds: 2.357 at 25 °C. Defining and counting the hydrogen bonds is not straightforward however. Because water may form hydrogen bonds with solute proton donors and acceptors, it may competitively inhibit the formation of solute intermolecular or intramolecular hydrogen bonds. Consequently, hydrogen bonds between or within solute molecules dissolved in water are almost always unfavorable relative to hydrogen bonds between water and the donors and acceptors for hydrogen bonds on those solutes. Hydrogen bonds between water molecules have an average lifetime of 10−11 seconds, or 10 picoseconds.
=== Stationary compound selection === The polarity of the solute is crucial for the choice of stationary compound, which in an optimal case would have a similar polarity as the solute. Common stationary phases in open tubular columns are cyanopropylphenyl dimethyl polysiloxane, carbowax polyethyleneglycol, biscyanopropyl cyanopropylphenyl polysiloxane and diphenyl dimethyl polysiloxane. For packed columns more options are available.
Peoples of the Altiplano had two large domesticated animals: llamas and alpacas. Among the food products made from the Peruvian camelids was sharqui, strips of freeze-dried meat, the origin of modern-day jerky. Another meat for royalty was that of the lizards known as Dicrodon holmbergi. It would be trapped as it attempted to consume the pods of Prosopis juliflora. After being trapped, it would be paralyzed and cooked until it was easily skinned. Afterwards, it was cooked for another ten minutes in heated sand and ashes then gutted, thus making it to be consumed immediately or preserved for up to a year. The meat of the common folk was the cuy, guinea pig. They were domesticated by 2000 BC and were easy to keep and multiplied rapidly. Guinea pigs were often cooked by stuffing them with hot stones. The entrails would often be used as an ingredient in soups along with potatoes, or made into a sauce. They could also be used for divination, which later brought them into disfavor by the Catholic Church. The Incas hunted game including the wild camelids vicuña and guanaco, whitetail deer, huemul deer and viscacha, a kind of chinchilla which was hunted with lassos. Hunting rights were controlled by the state and any meat would go into the state warehouses for storage. In massive royal hunts, hunting teams would force huge herds into enclosures, and there are reports of several thousand animals being caught in a single great hunt, including puma, bear, fox and deer. One mainstay of the Inca army and the general population was dried fish.
Sources: en.wikipedia.org
It is a four-amino-acid peptide built from alanine, glutamate, aspartate and glycine in that order. Its formula is C14H22N4O9, and it is made by chemical synthesis rather than extracted from tissue. The synthetic peptide is a single defined molecule, unlike the pineal extracts it is often compared with.
No. The two spellings refer to the same tetrapeptide, and the difference reflects transliteration from Russian. Laboratories and catalogues use both forms interchangeably. The material is also indexed as AEDG, taken from the one-letter codes of its residues.
Epithalamin is a mixed preparation derived from animal pineal tissue and contains many peptides. Epitalon is one synthetic sequence chosen for study from that broader mixture. Statements about one do not transfer directly to the other.
Mass spectrometry provides the identity check, because the observed mass is compared with the theoretical mass of the AEDG sequence. Chromatography separates and quantifies impurities but does not by itself prove which peptide is present. The two techniques are normally used together.