A practical reference on reversed-phase HPLC: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-02-07 and is reviewed periodically as new material appears.
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.
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.
Storage practice centres on limiting moisture, oxygen, and repeated temperature cycling. Freeze-dried powder is generally held desiccated at minus twenty degrees Celsius or colder and protected from light. Reconstituted solutions are markedly less stable, and the aspartate-glycine junction is prone to succinimide formation at neutral to mildly alkaline pH. Portioning material into single-use aliquots reduces degradation compared with repeated freeze-thaw cycles. Stability data specific to this tetrapeptide remain scarce, so most handling guidance is extrapolated from general peptide chemistry rather than measured directly.
Documentation accompanying research peptides usually includes a certificate of analysis listing the batch number, purity figure, and test methods applied. Buyers comparing suppliers should check whether the reported purity refers to chromatographic area or to a mass-balance calculation, because the two are not equivalent. Counter-ion content, residual solvents, and water content are sometimes omitted from such certificates even though they affect the actual peptide mass present. Independent verification through a second laboratory is the most direct way to confirm that a supplied material matches its label.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Derived from the four-residue sequence |
| Molar mass | About 390.35 g/mol | Free peptide, counter-ion not included |
| Appearance | White to off-white powder | Lyophilised solid from aqueous solution |
| Water solubility | Freely soluble | Short, polar peptide chain |
| Common synonyms | AEDG; epithalone | Catalogues use the names interchangeably |
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.
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.
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.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography with ultraviolet detection, frequently near 214 nanometers where the peptide bond absorbs. Mass spectrometry, most often with electrospray ionization, confirms the observed molecular mass and helps separate the intact peptide from truncated or modified forms. Amino acid analysis or tandem mass spectrometry can establish residue order. Purity is commonly quoted as an area percentage, yet such values are method-dependent, and comparisons between laboratories require matching column, gradient and detection wavelength.
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.
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.
The most widely cited claim is that epitalon activates telomerase and thereby extends telomere length. Supporting evidence comes largely from cultured human cells, where treatment was associated with increased telomerase activity and delayed replicative senescence. Telomerase activation is a biologically consequential effect, since the enzyme is largely silenced in most somatic cells. However, the route by which a short peptide would reach and act on the enzyme's regulatory machinery has not been established. Independent replication in human trials is scarce, so the link between cell-culture observations and whole-body aging remains an open question.
Human data are limited to small studies, often without the randomization, blinding, or control groups expected in contemporary clinical research. Reported outcomes have included changes in melatonin levels, immune markers, and subjective measures, but sample sizes were generally too small to support firm conclusions. Some reviews treat the peptide as promising while noting methodological weaknesses; others question whether the observed effects are specific. The compound is frequently discussed in longevity-focused communities, where enthusiasm often outpaces the published evidence. Separating established findings from speculation is therefore important when reading summaries of this research.
Epitalon emerged from research conducted in Saint Petersburg by Vladimir Khavinson and colleagues, who studied short peptides as potential regulators of aging. The work built on epithalamin, a pineal gland extract reported to influence neuroendocrine function. Epitalon was designed as a synthetic counterpart with a defined sequence, allowing reproducible experiments that extracts could not support. Early publications described effects on melatonin rhythms and lifespan in animal models. These findings circulated mainly in Russian-language journals during the 1990s, which limited their visibility among English-speaking researchers.
The two substrates of this enzyme are 17α-estradiol and reduced nicotinamide adenine dinucleotide (NAD+). Its products are estrone, reduced NADH, and a proton. The enzyme can also use the alternative cofactor, nicotinamide adenine dinucleotide phosphate. Estradiol 17alpha-dehydrogenase belongs to the oxidoreductase family, specifically those acting on the CH-OH group of donors with NAD+ or NADP+ as acceptors. The systematic name for this enzyme class is 17alpha-hydroxysteroid:NAD(P)+ 17-oxidoreductase. Commonly used names include 17alpha-estradiol dehydrogenase, 17alpha-hydroxy steroid dehydrogenase, 17alpha-hydroxy steroid oxidoreductase, 17alpha-hydroxysteroid oxidoreductase, and estradiol 17alpha-oxidoreductase. This enzyme plays a crucial role in both androgen and estrogen metabolism.
More than 90% of world industrial production of urea is for use as a nitrogen-release fertilizer. Urea has the highest nitrogen content of all solid nitrogenous fertilizers in common use. Therefore, it has a low transportation cost per unit of nitrogen nutrient. Urea breaks down in the soil to give ammonium ions (NH+4). The ammonium is taken up by the plant through its roots. In some soils, the ammonium is oxidized by bacteria to give nitrate (NO−3), which is also a nitrogen-rich plant nutrient. The loss of nitrogenous compounds to the atmosphere and runoff is wasteful and environmentally damaging so urea is sometimes modified to enhance the efficiency of its agricultural use. Techniques to make controlled-release fertilizers that slow the release of nitrogen include the encapsulation of urea in an inert sealant, and conversion of urea into derivatives such as urea-formaldehyde compounds, which degrade into ammonia at a pace matching plants' nutritional requirements. The most common impurity of synthetic urea is biuret, which impairs plant growth.
Some receptor agonists may cause downregulation of their respective receptors, while most receptor antagonists temporarily upregulate their respective receptors. The disequilibrium caused by these changes often causes withdrawal when the long-term use of a drug is discontinued. Upregulation and downregulation can also happen as a response to toxins or hormones. An example of upregulation in pregnancy is hormones that cause cells in the uterus to become more sensitive to oxytocin.
Sources: en.wikipedia.org
To start, the resting membrane potential of the Venus flytrap (−120 mV) is lower than animal cells (usually −90 mV to −40 mV). The lower resting potential makes it easier to activate an action potential. Thus, when an insect lands on the trap of the plant, it triggers a hair-like mechanoreceptor. This receptor then activates an action potential that lasts around 1.5 ms. This causes an increase of positive calcium ions into the cell, slightly depolarizing it. However, the flytrap does not close after one trigger. Instead, it requires the activation of two or more hairs. If only one hair is triggered, it disregards the activation as a false positive. Further, the second hair must be activated within a certain time interval (0.75–40 s) for it to register with the first activation. Thus, a buildup of calcium begins and then slowly falls after the first trigger. When the second action potential is fired within the time interval, it reaches the calcium threshold to depolarize the cell, closing the trap on the prey within a fraction of a second. Together with the subsequent release of positive potassium ions the action potential in plants involves an osmotic loss of salt (KCl). Whereas, the animal action potential is osmotically neutral because equal amounts of entering sodium and leaving potassium cancel each other osmotically. The interaction of electrical and osmotic relations in plant cells appears to have arisen from an osmotic function of electrical excitability in a common unicellular ancestors of plants and animals under changing salinity conditions.
== Further reading == Economy, Elizabeth C. (2018). The Third Revolution: Xi Jinping and the New Chinese State. Oxford University Press. ISBN 978-0-19-086607-5. Goodman, David S. G. (2015). Handbook of the Politics of China. Edward Elga. ISBN 978-1-78254-437-1. Li, Cheng (2014a). "Xi Jinping's Inner Circle (Part 2: Friends from Xi's Formative Years)" (PDF). Hoover Institution. Archived (PDF) from the original on 26 September 2020. Retrieved 15 July 2020. Simon, Denis Fred; Cong, Cao (2009). China's Emerging Technological Edge: Assessing the Role of High-End Talent. Cambridge University Press. ISBN 978-0-521-88513-3. Yang, Rufeng (2014). 習近平如何改變中國 [How Xi Jinping is changing China]. China Interpretation Series (in Chinese). Bonfire Limited. p. 12. ISBN 978-986-5721-05-3. Retrieved 23 August 2024. Zhu, Pengpeng (2007). 谜一样的人生 [A Mysterious Life] (in Chinese). Tianma Publishing. ISBN 978-0-9787999-2-2. Retrieved 23 August 2024.
Wounded healer is a term created by psychiatrist Carl Jung. The idea states that an analyst is compelled to treat patients because the analyst himself is "wounded." The idea may have Greek mythology origins. Victor et al. (2022) found that 82% of applied psychology graduate students and faculty members in the United States and Canada experienced mental health conditions at some point in their lives. As an example, of the "wounded healer phenomenon" between an analyst and their analyzed:
Sources: en.wikipedia.org
In the 2010s, Ells tried to diversify the company by creating or acquiring several subsidiaries. These subsidiaries offered very different cuisines compared to their parent company. Examples include soul food (Soul Daddy), Asian cuisine (ShopHouse Southeast Asian Kitchen), pizza (Pizzeria Locale), and burgers (Tasty Made). In 2023, Chipotle had also tried incorporating California-inspired bowls into the Farmesa Fresh Eatery concept. The few test locations were not a financial success, and all concepts were discontinued. In 2011, Steve Ells was a judge for the TV show America's Next Great Restaurant and investor of ANGR Holdings, the company that would launch the winning concept's restaurants. Chipotle agreed to purchase Ells' investment in ANGR at his cost, provide support for ANGR operations, and invest a total of $2.3 million in cash contributions. The winning concept, Soul Daddy, was quickly closed after operating for eight weeks. In September 2011, Chipotle opened an Asian fast-casual concept restaurant named ShopHouse Southeast Asian Kitchen in Washington, D.C. The company said the new restaurant "would follow the Chipotle service format and its focus on 'food with integrity' in ingredients". Chipotle's plan was to start with only one store and see how the restaurant worked out before expanding the concept. On July 29, 2016, the company announced the opening of its first Tasty Made burger restaurant in the fall.
=== Anatomy === The blood-brain barrier protects the brain by restricting the ability of large molecules to cross the barrier between the blood, CSF, and interstitial fluid of the brain. ICV injection circumvents this barrier, to be able to deliver drugs to the CSF. An ICV device is implanted under the scalp, into the subgaleal space where it is then connected to the ventricles with an outlet catheter. This allows for repeated doses of the drug without having to re-puncture the scalp. Production of CSF is at a rate of about .3 mL/minute and occurs at the ependymal and parenchymal regions and the choroid plexus. Up to 80 percent of CSF production comes from the choroid plexus, which is present within the lateral, third, and fourth ventricles. The choroid is lined with epithelium with tight junctions at the ventricular side of the cells. This comprises the blood-CSF barrier. Whereas the blood-brain barrier is made up of vascular endothelium in capillary beds throughout the CNS parenchyma.
I cannot remember how they first came to be offered to us. But they were distributed in the dressing rooms. We didn't have to take them but most of the players did. The tablets were mostly white but once or twice they were yellow. They were used through the 1961–62 season and the championship season which followed it. Drug-taking had previously been virtually unnamed in the club. But once it had started we could have as many tablets as we liked. On match days they were handed out to most players as a matter of course. Soon some of the players could not do without the drugs. The club agreed that drugs had been used but that they "could not possibly have had any harmful effect." Dunlop, however, said he had become an addict. In November 1942, the Italian cyclist Fausto Coppi took "seven packets of amphetamine" to beat the world hour record on the track. In 1960, the Danish rider Knud Enemark Jensen collapsed during the 100 km team time trial at the Olympic Games in Rome and died later in hospital. The autopsy showed he had taken amphetamine and another drug, Ronicol, which dilates the blood vessels. The chairman of the Dutch cycling federation, Piet van Dijk, said of Rome that "dope – whole cartloads – [were] used in such royal quantities." The 1950s British cycling professional Jock Andrews would joke: "You need never go off-course chasing the peloton in a big race – just follow the trail of empty syringes and dope wrappers." The Dutch cycling team manager Kees Pellenaars told of a rider in his care:
On September 25, Xi and Peng returned to the White House with Donald and Melania Trump. They then attended a tea ceremony in the Red Room. Trump said US farmers "are going to be very happy" with the talks, adding "A lot of very positive things happened, but America is very happy about this visit and I’m sure China is very happy also". He said "We’ve had a tremendous visit from two spectacular people" and "We’ve really enjoyed it and I think we’ve been tremendous strides. We’ve made great strides, very positive for both countries." During this tea ceremony, Xi said that he and Trump "are like two people who are charting the course for the great ship of China-U.S. relations." Xi also confirmed that two leaders will to see each other later this year in twice, including APEC summit in Shenzhen and G20 Summit in Miami. Later, Xi and Trump visited the National Archives, and viewed the Declaration of Independence, the Constitution and the Bill of Rights. According to the NPR, a table that included a temporary display showcasing a brick from the Great Wall of China and an 19th century scroll sent by a Qing emperor was removed because the display also planned to show the Treaty of San Francisco, which China considers as illegitimate because it was not a signatory. Other documents, including Six Assurances and the Three Communiqués, were also discussed for display, but ultimately not included.
Sources: en.wikipedia.org
It is a synthetic tetrapeptide built from alanine, glutamate, aspartate and glycine. The four residues are joined by standard peptide bonds, giving a linear chain rather than a branched structure.
The name derives from epithalamin, a pineal gland extract studied in the former Soviet Union. Researchers proposed that short fragments of that extract carried the biological activity of interest.
No major regulatory agency has approved it as a medicine. It is handled as a research chemical, and products sold under this name are not standardised drugs with defined clinical labelling.
Reversed-phase high-performance liquid chromatography with ultraviolet detection at 214 nanometres is the usual approach. Peak area percentage provides a purity figure relative to other components in the sample. Mass spectrometry is then applied to confirm identity.