This is a working overview of RP-HPLC, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-03-19 and is reviewed periodically as new material appears.
The compound is described in the literature as a derivative of epithalamin, a preparation obtained from bovine pineal tissue. Work on this peptide family was carried out mainly by a research group in Saint Petersburg beginning in the 1980s, and the substance was later registered for clinical use in Russia under the name Epitalon. Outside that region it is generally treated as a research chemical rather than an approved medicine. Statements about its biological activity rest on a relatively small number of studies, and independent replication remains limited.
In its supplied form epitalon is a white to off-white powder, usually lyophilized and often hygroscopic. It dissolves readily in water and in aqueous buffers, and it is commonly handled as the acetate or trifluoroacetate salt to improve stability during purification and drying. The amide backbone is labile in aqueous media, so solutions are less durable than the dry solid. Handling notes in the chemical literature therefore emphasize keeping the powder dry, cool and shielded from light until it is dissolved.
No national medicines regulator has approved epitalon as a therapeutic product. It is generally distributed as a research chemical, and in some jurisdictions selling peptides for human consumption without approval is restricted or prohibited. Certificates of analysis accompanying commercial material vary in which tests are performed, and independent verification of identity and purity is uncommon. Statements about anti-ageing or disease-prevention benefits on vendor pages are marketing claims rather than regulatory findings, a distinction that shapes how the compound is discussed in scientific and popular sources alike.
The most frequently cited laboratory finding is that AEDG increased telomerase activity and extended telomere length in cultured human somatic cells. That work used fetal fibroblast strains and reported changes in enzyme activity alongside altered division counts. Replication by unrelated groups has been limited, and the published record is largely a single-laboratory series rather than a multi-centre programme. The result supports a hypothesis about peptide influence on gene expression in cell culture; it does not by itself establish an effect on telomere length in living animals or in people.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic tetrapeptide | Four residues, linear chain |
| Residue sequence | Ala-Glu-Asp-Gly | Single-letter form AEDG |
| Calculated mass | 390.3 daltons | Value for the free, uncharged form |
| Appearance | White to off-white powder | Usually supplied lyophilized |
| Solubility | Freely soluble in water | Often handled as a salt form |
Epitalon is a synthetic tetrapeptide with the residue sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its monoisotopic mass is approximately 390.35 daltons, and it is usually supplied as a lyophilised trifluoroacetate or acetate salt. The compound was derived from a pineal gland extract called epithalamin, a heterogeneous preparation investigated in the former Soviet Union. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology described the tetrapeptide as a constituent fragment of that extract. Commercial material is offered as a laboratory reagent rather than as a finished pharmaceutical product.
Literature searches for this compound must account for several spelling variants. Indexing databases contain epitalon, epithalon, epithalone, and AEDG, and relevant records are scattered across Russian-language and English-language journals that do not consistently cross-cite. Early publications describe the parent extract as a mixture of many peptides, whereas later work addresses the single synthetic tetrapeptide. That shift in nomenclature complicates comparison between studies, because extract data and tetrapeptide data are sometimes cited interchangeably. A search strategy omitting the alternate spellings will return an incomplete set of references.
Identity is normally established by reversed-phase high-performance liquid chromatography combined with mass spectrometry, a pairing that separates components and confirms molecular mass at once. Purity is quoted as a percentage from the chromatogram, and figures above ninety-five percent are a frequent commercial specification. Amino acid analysis or sequencing supplies further confirmation when required. Because many short peptides behave similarly under chromatography, retention time alone does not establish sequence; the mass measurement is what separates one tetrapeptide from another, and certificates should report both.
Short peptides such as AEDG are normally supplied as a freeze-dried solid and are kept dry, cold, and shielded from light. Holding at minus twenty degrees Celsius is common for the long term, while a refrigerator suffices for brief periods before use. The material takes up moisture to some degree, so containers should stay sealed and be allowed to reach room temperature before opening, which limits condensation on the contents. Repeated warming and cooling of a single container is discouraged because it admits water and can lower the amount of intact peptide.
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.
A large number of benzodiazepine derivatives have been synthesised and their structure-activity relationships explored in detail. This chart contains binding data for benzodiazepines and related drugs investigated by Roche up to the late 1990s (though in some cases the compounds were originally synthesised by other companies such as Takeda or Upjohn). Other benzodiazepines are also listed for comparison purposes, but it does not however include binding data for;
=== Anticoagulant medications === Anticoagulants may be started if the TIA is thought to be attributable to atrial fibrillation. Atrial fibrillation is an abnormal heart rhythm that may cause the formation of blood clots that can travel to the brain, resulting in TIAs or ischemic strokes. Atrial fibrillation increases stroke risk by five times, and is thought to cause 10-12% of all ischemic strokes in the US. Anticoagulant therapy can decrease the relative risk of ischemic stroke in those with atrial fibrillation by 67% Direct acting oral anticoagulants (DOACs), such as apixaban, are as effective as warfarin while also conferring a lower risk of bleeding. Generally, anticoagulants and antiplatelets are not used in combination, as they result in increased bleeding risk without a decrease in stroke risk. However, combined antiplatelet and anticoagulant therapy may be warranted if the patient has symptomatic coronary artery disease in addition to atrial fibrillation. Sometimes, myocardial infarction ("heart attack") may lead to the formation of a blood clot in one of the chambers of the heart. If this is thought to be the cause of the TIA, people may be temporarily treated with warfarin or another anticoagulant to decrease the risk of future stroke.
Reversed-phase liquid chromatography (RP-LC) is a mode of liquid chromatography in which non-polar stationary phase and polar mobile phases are used for the separation of organic compounds. In the reversed phase mode, the more hydrophobic sample components are retained in the system for longer. The vast majority of separations and analyses using high-performance liquid chromatography (HPLC) in recent years are done using the reversed phase mode. First developed for separating biomolecules, it is now a general technique with many stationary phases available for use in RP-LC, allowing great flexibility in the development of the separation methods. Some factors affect how the components are retained and separated in RP-LC:
==== Kidney problems ==== Kidney tests revealed that nine of the ten steroid users developed a condition called focal segmental glomerulosclerosis, a type of scarring within the kidneys. The kidney damage in the bodybuilders has similarities to that seen in morbidly obese patients, but appears to be even more severe.
Parmotrema perlatum is used as a spice, particularly in the cuisine of Tamil Nadu. It is especially prevalent in Chettinad cuisine, being used in the popular rice dish biryani, and also in many meat and vegetarian dishes. In its raw state, black stone flower does not have much taste or fragrance. However, when put in contact with heat, especially hot cooking oil or ghee, it releases a distinctive earthy, smoky flavour and aroma. This property of black stone flower is especially valued in the tempering step of cooking a number of Indian dishes. The spice is also integral to various regional masalas throughout the Indian subcontinent. Parmotrema perlatum is a key ingredient in masalas such as Kala and Goda masala of Maharashtra, Anglo-Indian bottle masala, bhojwar masala from Hyderabad, and potli masala in Lucknow. It is what many cooks and commercial spice blend makers believe sets apart accomplished dishes from those made by amateurs. Despite its lack of a specific aroma or describable flavour in its raw form, its contribution to the complex flavour profile of these spice blends is highly valued.
Sources: en.wikipedia.org
For comparison with lower dosages, the suppression of circulating testosterone levels in men with a dosage of 100 mg/day oral CPA was 77% and with a dosage of 300 mg/week intramuscular CPA was 76%. Dosages of CPA of 12.5 to 25 mg/day have been used as a maintenance dosage for testosterone suppression in men with sexual deviance after initial administration of higher CPA dosages, without recurrence of symptoms. CPA is generally able to maximally suppress circulating testosterone levels by 70 to 80% in men. However, in spite of strong suppression of testosterone levels, CPA, at least by itself (e.g., without estrogen), is not usually able to reduce testosterone levels into the castrate/female range (<50 ng/dL) at any dosage, and testosterone levels generally remain just above it at levels of roughly 50 to 200 ng/dL. However, studies have reported that a very high dosage of CPA of 300 mg/day may suppress testosterone levels to around 50 ng/dL in men. CPA also suppresses estradiol levels in men, with one study finding about a 65% decrease in estradiol levels (from about 27 pg/mL to around 10 pg/mL) with 100 mg/day CPA. CPA has been found to maximally suppress testosterone and estradiol levels in young men within 7 days of continuous administration. Following discontinuation of CPA, the recovery of testosterone levels is variable and may require 14 days to 6 months for completion. An escape or recovery phenomenon, in which testosterone levels increase over time, has been observed with long-term CPA monotherapy.
Normative ESC values have also been established for pediatric age groups, and it has been demonstrated that ESC values begin to decrease in the eighth decade of life. ESC has the potential to be a useful tool for detecting small fiber neuropathies. It is highly sensitive, rapid, more accessible and less technically complex than current gold standard sudomotor function tests, and causes minimal-to-no patient discomfort, so very suitable for routine use.
=== Former markets === Russia – Pizza Hut began operating in Russia in 1991, when food supplies dwindled during the 1991 Soviet coup d'état attempt, prompting Russian president Boris Yeltsin to call Pizza Hut deliveries. Pizza Hut suspended operations in response to the 2022 Russian invasion of Ukraine. Later some restaurants re-opened operations under rebranded new trademark PittsaN (ПиццаН). Panama – In 2022, the Pizza Hut chain ceased its operations in Panamanian lands after reporting economic losses. Argentina – Pizza Hut opened in Argentina in 1983; however, they withdrew some time later. They returned in the mid-1990s but withdrew again in 1998 due to poor sales success. It was announced that it will be brought back to the country in 2025, but the exact date has not been confirmed. Chile – In 2025, the Pizza Hut chain downsized its operations in Chile as one of its two franchising concerns, Food Delivery Brands (which also handled Telepizza), went bankrupt as a result of the economic crisis the country had faced in the past decade and increasing competition from rival chains such as Little Caesars and Papa John's.
== Toxicodynamics == Apamin is the smallest neurotoxin polypeptide known, and the only one that passes the blood-brain barrier. Apamin thus reaches its target organ, the central nervous system. Here it inhibits small-conductance Ca2+-activated K+ channels (SK channels) in neurons. These channels are responsible for the afterhyperpolarizations that follow action potentials, and therefore regulate the repetitive firing frequency. Three different types of SK channels show different characteristics. Only SK2 and SK3 are blocked by apamin, whereas SK1 is apamin insensitive. SK channels function as a tetramer of subunits. Heteromers have intermediate sensitivity. SK channels are activated by the binding of intracellular Ca2+ to the protein calmodulin, which is constitutively associated to the channel. Transport of potassium ions out of the cell along their concentration gradient causes the membrane potential to become more negative. The SK channels are present in a wide range of excitable and non-excitable cells, including cells in the central nervous system, intestinal myocytes, endothelial cells, and hepatocytes. Binding of apamin to SK channels is mediated by amino acids in the pore region as well as extracellular amino acids of the SK channel. It is likely that the inhibition of SK channels is caused by blocking of the pore region, which hinders the transport of potassium ions. This will increase the neuronal excitability and lower the threshold for generating an action potential. Other toxins that block SK channels are tamapin and scyllatoxin.
Sources: en.wikipedia.org
Herbie Hancock – electric piano (Rhodes, clavinet), synthesizer/FX Melvin "Wah Wah" Ragin – guitar Ray Parker Jr. – guitar Paul Jackson – electric bass James Levi – drums Kenneth Nash – percussion Bennie Maupin – tenor & soprano saxophones, lyricon
== Homology == Several organisms possess multiple CPA2 paralogues. Thus, E. coli has three, Methanococcus jannaschii has four and Synechocystis sp. has five paralogues. The potassium efflux system, Kef, protects bacteria against the detrimental effects of electrophilic compounds via acidification of the cytoplasm. Kef is inhibited by glutathione (GSH) but activated by glutathione-S-conjugates (GS-X) formed in the presence of electrophiles. GSH and GS-X bind to overlapping sites on Kef, which are located in a cytosolic regulatory domain.
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== Bibliography == Brown, M.S, Engelking, L.J, Evers, B, Goldstein, J.L, Hammer, R.E, Horton, J.D, Kuriyama, H, Liang, G, Li, W.P, & Liang, G 2005, 'Schoenheimer effect explained - Feedback regulation of cholesterol synthesis in mice mediated by Insig proteins', The Journal of clinical investigation, vol. 115, pp. 2489–98 Clarke, Hans T (12 December 1941). "Rudolf Schoenheimer, 1898-1941". Science, New Series. 94: 553–554. Cooper, D.Y, & Osborn, M.E 1999, 'Schoenheimer, Rudolph', American National Biography Helmenstine, A.M 2019, 'Deuterium Facts', https://www.thoughtco.com/facts-about-deuterium-607910 Engelking, L. J. (2005-08-25). "Schoenheimer effect explained - feedback regulation of cholesterol synthesis in mice mediated by Insig proteins". Journal of Clinical Investigation. 115 (9): 2489–2498. doi:10.1172/jci25614 ISSN 0021-9738. Fruton, Joseph S. (January 1982). "The carbobenzoxy method of peptide synthesis". Trends in Biochemical Sciences. 7 (1): 37–39. doi:10.1016/0968-0004(82)90064-0 ISSN 0968-0004. Hargrove, James L. (1998). Dynamic modeling in the health sciences. Springer. pp. ix. ISBN 0-387-94996-8. OCLC 876222114 Helmenstine, A.M (2019). "Deuterium Facts". Kohler R, Jr 1977, 'Rudolph Schoenheimer, Isotopic Tracers, and Biochemistry in the 1930s', Historical Studies in the Physical Sciences, vol. 8, pp. 257–298 Medawar, Jean: Pyke, David (2012). Hitler's Gift: The True Story of the Scientists Expelled by the Nazi Regime (Paperback). New York: Arcade Publishing. ISBN 978-1-61145-709-4.{{cite book}}: CS1 maint: multiple names: authors list (link) Quastel J.H.
=== Central & East Indo-Pacific === 2024 Vietnamese export of pangasius maw has increased to about US$58,000,000, with 38% going to China and the rest to Thailand, Malaysia, Singapore and the USA. The Vietnam News Agency claims that the falling totoaba population has incentivized Chinese import of alternative maw. The island and seas of New Guinea see significant fish maw production. Since 2012, in and around the Kikori River delta of Papua New Guinea, the scaly croaker Nibea squamosa has been targeted in gillnetting for its extremely high-priced maw, selling for as much as US$15,615 per kilogram.
Sources: en.wikipedia.org
The peptide contains four residues in the order alanine, glutamate, aspartate and glycine, abbreviated AEDG. The chain is linear and held together by three peptide bonds. Its calculated mass for the uncharged free form is about 390.3 daltons.
Epithalamin refers to a crude preparation derived from bovine pineal tissue, which contains many components. Epitalon is a single synthetic tetrapeptide identified from that material and produced by chemical synthesis. The two names are sometimes confused because early reports treated the synthetic peptide as an active fragment of the extract.
It has been registered for clinical use in Russia, where it is associated with a small family of short peptides. In most other jurisdictions it is not an approved medicine and is traded as a research chemical. Regulatory status varies by country and changes over time.
Small studies with human participants have been reported, chiefly in Russian-language journals, but they are limited in size and design. No large randomised controlled trial with published results is available.