This is a working overview of reversed-phase HPLC, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-12-21. Anything still debated is marked as such rather than presented as settled.
Because epitalon has no pharmacopoeial monograph, quality assessment depends on supplier documentation and independent testing. Certificates of analysis typically report a purity figure from a single chromatographic run, a measured mass and sometimes an appearance description, but methods and acceptance criteria are not harmonised across vendors. Third-party laboratories can repeat identity and purity measurements, and mismatches between labelled and measured peptide content have been described for research peptides generally. What constitutes adequate identity confirmation for a molecule of this size stays an open question, since mass agreement alone does not separate closely related sequences.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Analytical method | Reversed-phase HPLC | Purity determination, typically 214 nm |
| Mass confirmation | ESI or MALDI mass spectrometry | Compared with mass near 390 Da |
| Common synonyms | Epitalon, epithalon, AEDG | Naming differs between suppliers |
| Storage temperature | −20 °C or lower | Lyophilised powder, kept desiccated |
| Solution stability | Limited in neutral aqueous buffer | Aspartimide and hydrolysis pathways |
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.
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.
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.
The compound is generally described as a synthetic analogue of a fragment isolated from a pineal gland extract. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology introduced it during the 1980s and 1990s while studying short peptides from animal tissue. The original extract, called epithalamin, is a heterogeneous mixture, whereas epitalon is a single defined sequence. That distinction matters because findings reported for the extract are not automatically findings about the pure tetrapeptide, and claims about broader biological effects remain a separate question from the chemical identity described here.
Lyophilised epitalon is generally held at minus twenty degrees Celsius in a sealed container kept dry and dark. Cooler conditions are sometimes recommended for long-term archives. The solid takes up moisture readily enough that repeated opening of a vial introduces water, so dividing a batch into smaller portions before storage lowers degradation risk. Aqueous solutions are less durable than the dry powder and are usually prepared shortly before use, then kept cold and shielded from light to slow hydrolysis and oxidation.
Verification of research-grade material involves comparing a supplier chromatogram against an in-house reference, checking the observed mass against the calculated value, and where possible confirming residue order by tandem mass spectrometry or enzymatic peptide mapping. Purity claims should be read alongside the method used to obtain them, because detection wavelength and integration settings alter the result. Batch-specific data, rather than a generic grade statement, is the informative part of a certificate.
Identity and purity of epitalon samples are normally established by reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, combined with mass spectrometry. The mass spectrum confirms the expected molecular ion and can reveal truncated or oxidised by-products. Amino acid analysis after acid hydrolysis verifies that the four residues are present in the expected ratio. Certificates typically report a purity figure taken from chromatographic peak area, expressed as a percentage of total integrated signal.
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.
=== Tip designs === Syringes come with a number of designs for the area in which the blade locks to the syringe body. Perhaps the most well known of these is the Luer lock, which simply twists the two together. Bodies featuring a small, plain connection are known as slip tips and are useful for when the syringe is being connected to something not featuring a screw lock mechanism. Similar to this is the catheter tip, which is essentially a slip tip but longer and tapered, making it good for pushing into things where there the plastic taper can form a tight seal. These can also be used for rinsing out wounds or large abscesses in veterinary use. There is also an eccentric tip, where the nozzle at the end of the syringe is not in the centre of the syringe but at the side. This causes the blade attached to the syringe to lie almost in line with the walls of the syringe itself and they are used when the blade needs to get very close to parallel with the skin (when injecting into a surface vein or artery for example).
==== Lamellipodia ==== A meshwork of actin filaments marks the forward edge of a moving cell, and the polymerization of new actin filaments pushes the cell membrane forward in protrusions called lamellipodia. These membrane protrusions then attach to the substrate, forming structures known as focal adhesions that connect to the actin network. Once attached, the rear of the cell body contracts squeezing its contents forward past the adhesion point. Once the adhesion point has moved to the rear of the cell, the cell disassembles it, allowing the rear of the cell to move forward.
=== Optimization of protein crystallization conditions === Although proteins are dynamic structures in solution, formation of protein crystals is expected to be favored when all molecules lie in their lowest energy conformation. Thermofluor evaluation of conditions that stabilize proteins is consequently a useful strategy for finding optimal crystallization conditions
Miraculin, is a glycoprotein extracted from Synsepalum dulcificum a berry which alters human tongue receptors to recognize sour foods as sweet. Variable surface glycoproteins allow the sleeping sickness Trypanosoma parasite to escape the immune response of the host. The viral spike of the human immunodeficiency virus is heavily glycosylated. Approximately half the mass of the spike is glycosylation and the glycans act to limit antibody recognition as the glycans are assembled by the host cell and so are largely 'self'. Over time, some patients can evolve antibodies to recognise the HIV glycans and almost all so-called 'broadly neutralising antibodies (bnAbs) recognise some glycans. This is possible mainly because the unusually high density of glycans hinders normal glycan maturation and they are therefore trapped in the premature, high-mannose, state. This provides a window for immune recognition. In addition, as these glycans are much less variable than the underlying protein, they have emerged as promising targets for vaccine design. P-glycoproteins are critical for antitumor research due to its ability block the effects of antitumor drugs. P-glycoprotein, or multidrug transporter (MDR1), is a type of ABC transporter that transports compounds out of cells. This transportation of compounds out of cells includes drugs made to be delivered to the cell, causing a decrease in drug effectiveness. Therefore, being able to inhibit this behavior would decrease P-glycoprotein interference in drug delivery, making this an important topic in drug discovery.
Loperamide is an opioid-receptor agonist and acts on the μ-opioid receptors in the myenteric plexus of the large intestine. It works like morphine, decreasing the activity of the myenteric plexus, which decreases the tone of the longitudinal and circular smooth muscles of the intestinal wall. This increases the time material stays in the intestine, allowing more water to be absorbed from the fecal matter. It also decreases colonic mass movements and suppresses the gastrocolic reflex. Loperamide's circulation in the bloodstream is limited in two ways. Efflux by P-glycoprotein in the intestinal wall reduces the passage of loperamide, and the fraction of drug crossing is then further reduced through first-pass metabolism by the liver. Loperamide metabolizes into an MPTP-like compound, but is unlikely to exert neurotoxicity.
Sources: en.wikipedia.org
== January 1, 1982 (Friday) == Javier Pérez de Cuéllar of Peru, took office for a five-year term as the fifth Secretary-General of the United Nations, succeeding Kurt Waldheim of Austria. On the same day, the nations of Togo, Zaire, Jordan, Guyana and Poland became the new non-permanent members of the UN Security Council to begin a two-year term and replacing Niger, Tunisia, the Philippines, Mexico and East Germany. After the 1980 launch of Cable News Network, a second cable television network, CNN2, began telecasting, originally as a format of national news shown live every 30 minutes. Seven months later, it would be renamed Headline News. Denise LeClair anchored the first newscast. In American college football, with the championship of the top teams determined by rankings a poll of sports writers by the Associated Press (AP), a poll of coaches by United Press International (UPI), and the results of postseason college bowl games, the #1-ranked Clemson University Tigers (11–0–0) defeated the #4-ranked University of Nebraska Cornhuskers (9–2–0), 22 to 15, in the Orange Bowl game in Miami before a crowd of 72,748 fans. The #2-ranked Georgia Bulldogs were upset, 24–20 in the Sugar Bowl game in New Orleans by the #10-ranked Pitt Panthers (who had been ranked No. 1 until the last game of the regular season), and the #3 Alabama Crimson tide lost, 14–12, to the #6 Texas Longhorns at the Cotton Bowl game in Dallas.
== Epidemiology == Obesity prevalence in Brazil has increased steadily over recent decades. Data from the Vigitel surveillance system indicate that the prevalence of obesity among adults increased from 11.8% in 2006 to 25.7% in 2024. During the same period, the prevalence of excess weight increased from 42.6% to 62.6%. The increase corresponds to a growth of approximately 118% in obesity prevalence over an eighteen-year period. No sustained decline was observed during the surveillance period. A systematic review and meta-analysis published in 2024 estimated the pooled prevalence of obesity among Brazilian adults at approximately 20%, with higher prevalence observed in the South and Southeast regions.
=== Soundproofing === Researchers demonstrated a graphene-oxide-based aerogel that could reduce noise by up to 16 decibels. The aerogel weighed 2.1 kilograms per cubic metre (0.13 lb/cu ft). A conventional polyester urethane sound absorber might weigh 32 kilograms per cubic metre (2.0 lb/cu ft). One possible application is to reduce sound levels in airplane cabins.
=== Turkey === The first therapies in Turkey using 177Lu-DOTATATE PRRT were carried out in early 2014, for treatment of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) at the Istanbul University-Cerrahpaşa.
=== Connective tissue === Connective tissues are fibrous and made up of cells scattered among inorganic material called the extracellular matrix. Often called fascia (from the Latin "fascia", meaning "band" or "bandage"), connective tissues give shape to organs and hold them in place. The main types are loose connective tissue, adipose tissue, fibrous connective tissue, cartilage and bone. The extracellular matrix contains proteins, the chief and most abundant of which is collagen. Collagen plays a major part in organizing and maintaining tissues. The matrix can be modified to form a skeleton to support or protect the body. An exoskeleton is a thickened, rigid cuticle which is stiffened by mineralization, as in crustaceans or by the cross-linking of its proteins as in insects. An endoskeleton is internal and present in all developed animals, as well as in many of those less developed.
Sources: en.wikipedia.org
MDMA is an entactogen or empathogen, as well as a stimulant, euphoriant, and weak psychedelic. It is a substrate of the monoamine transporters (MATs) and acts as a monoamine releasing agent (MRA). The drug is specifically a well-balanced serotonin–norepinephrine–dopamine releasing agent (SNDRA). To a lesser extent, MDMA also acts as a serotonin–norepinephrine–dopamine reuptake inhibitor (SNDRI). MDMA enters monoaminergic neurons via the MATs and then, via poorly understood mechanisms, reverses the direction of these transporters to produce efflux of the monoamine neurotransmitters rather than the usual reuptake. Induction of monoamine efflux by amphetamines in general may involve intracellular Na+ and Ca2+ elevation and PKC and CaMKIIα activation. MDMA also acts on the vesicular monoamine transporter 2 (VMAT2) on synaptic vesicles to increase the cytosolic concentrations of the monoamine neurotransmitters available for efflux. By inducing release and reuptake inhibition of serotonin, norepinephrine, and dopamine, MDMA increases levels of these neurotransmitters in the brain and periphery and thereby indirectly activates the receptors of these neurotransmitters. There are species differences in the balance of MAT activities of MDMA, with it showing greater influence on serotonin in rodents than in humans. In addition to its actions as an SNDRA, MDMA directly interacts with a number of monoamine and other receptors.
Anderson obtains the access code to Ma-Ma's apartment from the mind of her computer expert and releases him after viewing his memories of torture and coercion at Ma-Ma's hands. Dredd admonishes her decision to release a suspect as a fail point and a crime. Anderson, in response, reminds him she already failed the assessment by being disarmed, and considers the computer expert a victim. The Judges infiltrate Ma-Ma's apartment where they kill most of her enforcers, although Anderson is shot and wounded. Ma-Ma reveals that, if Dredd kills her, a device on her wrist will detonate explosives on the top floors, destroying the building. Reasoning that the detonator's signal will not reach the explosives from the ground floor, Dredd forces Ma-Ma to inhale Slo-Mo and throws her down the atrium to her death. With order restored, the Judges leave Peach Trees as reinforcements arrive. Dredd tells Anderson her assessment is complete and she surrenders her badge before leaving. The Chief Judge asks Dredd about Anderson's performance; he responds that she has passed.
=== Fuels === The dominant use of alkanes is as fuels. Propane and butane, easily liquified gases, are commonly known as liquified petroleum gas (LPG). From pentane to octane the alkanes are highly volatile liquids. They are used as fuels in internal combustion engines, as they vaporize easily on entry into the combustion chamber without forming droplets, which would impair the uniformity of the combustion. Branched-chain alkanes are preferred as they are much less prone to premature ignition, which causes knocking, than their straight-chain homologues. This propensity to premature ignition is measured by the octane rating of the fuel, where 2,2,4-trimethylpentane (isooctane) has an arbitrary value of 100, and heptane has a value of zero. Apart from their use as fuels, the middle alkanes are also good solvents for nonpolar substances. Alkanes from nonane to, for instance, hexadecane (an alkane with sixteen carbon atoms) are liquids of higher viscosity, less and less suitable for use in gasoline. They form instead the major part of diesel and aviation fuel. Diesel fuels are characterized by their cetane number, cetane being an old name for hexadecane. However, the higher melting points of these alkanes can cause problems at low temperatures and in polar regions, where the fuel becomes too thick to flow correctly.
They called for further research on the subject, as chlorpromazine is a cheap benchmark drug and one of the most used treatments for schizophrenia worldwide. Chlorpromazine has also been used in porphyria and as part of tetanus treatment. It is still recommended for short-term management of severe anxiety and psychotic aggression. Resistant and severe hiccups, severe nausea/emesis, and preanesthetic conditioning are other uses. Symptoms of delirium in hospitalized AIDS patients have been effectively treated with low doses of chlorpromazine.
== Research == Butler is a heart failure expert, with research spanning prevention to advanced therapies, including cardiac transplantation and ventricular assist devices. He has published more than 1,500 peer-reviewed publications. He has led or participated in over 100 clinical trials, developed the Atlanta Cardiomyopathy Consortium, and helped establish the NIH-funded Heart Failure Network at Emory University. Butler is a senior consulting editor for the Journal of the American College of Cardiology associate editor for the European Heart Journal section editor for the Journal of the American College of Cardiology: Heart Failure guest editor for the European Journal of Heart Failure, and serves on the editorial board of Circulation. He has also peer-reviewed for journals, including the New England Journal of Medicine, Journal of the American Medical Association (JAMA), and Lancet.
Sources: en.wikipedia.org
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.
Neutral and slightly basic aqueous conditions promote aspartimide formation at the aspartate-glycine step, often followed by deamidation. Elevated temperature and repeated freeze-thaw cycles accelerate the loss. Acidic solutions and dry lyophilised powder are comparatively stable over short periods.
No monograph exists in the United States Pharmacopeia or the European Pharmacopoeia, and no widely distributed certified reference standard is available. Purity and identity therefore rest on supplier methods that are not harmonised. This absence is the main reason reported purities are difficult to compare between sources.
No. Epithalamin is a peptide-containing extract of bovine pineal glands, while epitalon is a single synthetic tetrapeptide. The extract contains many peptides and other tissue components, so its composition varies between batches in ways that a synthesised sequence does not.