Research chemical raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-03-24. Anything still debated is marked as such rather than presented as settled.
Identity and purity are checked by reversed-phase high-performance liquid chromatography, usually with ultraviolet detection near 214 nanometres, where the peptide bond absorbs. Mass spectrometry confirms the expected mass and reveals whether truncation products or adducts are present. Acid hydrolysis followed by amino acid analysis gives the residue ratio, which should approximate one alanine, one glutamate, one aspartate and one glycine. Counter-ions such as acetate or trifluoroacetate remain in the dried product and lower net peptide content, so a stated purity figure on a label does not by itself describe how much peptide a vial holds.
Regulatory treatment differs by country. No formulation of epitalon holds a marketing authorisation as a medicine in the United States or the European Union, where material sold for laboratory use is handled as a research chemical and is not intended for human consumption. In Russia, several short peptide preparations from the same institute's peptide series are registered medicinal products, and epitalon appears in that national context. Elsewhere it is frequently offered as a cosmetic ingredient, a category with lighter requirements. Advertising claims about longevity or disease prevention are restricted in most jurisdictions, which limits how sellers describe the compound.
Freeze-dried epitalon is normally kept at minus twenty degrees Celsius in a sealed, desiccated container, protected from light. Short excursions at ambient temperature during shipping are generally tolerated, but repeated warming and cooling cycles encourage moisture uptake, which shortens shelf life. Once dissolved, the peptide is far less stable than the solid: aqueous solutions are subject to hydrolysis and to deamidation at the aspartate and glutamate residues. Working solutions are therefore held refrigerated and used within days, and repeated freezing and thawing of the same vial is best avoided.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Storage temperature, solid | Approximately -20 C | Sealed, desiccated, protected from light |
| Typical identity method | Electrospray mass spectrometry | Protonated ion expected near 391 |
| Typical purity method | Reversed-phase HPLC | Ultraviolet detection near 214 nm |
| Common synonyms | Epithalon, epithalone, AEDG | Spelling variants appear in supplier catalogues |
| Solution stability | Days at 2-8 C | Hydrolysis and deamidation limit shelf life |
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 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.
Epitalon is a synthetic tetrapeptide whose sequence is alanine-glutamate-aspartate-glycine, written in single-letter code as AEDG. The four residues are joined by three peptide bonds, giving a linear backbone with no branching and no disulfide bridges. Its calculated molecular mass for the free form is approximately 390.3 daltons, a figure that rises when the compound is supplied as an acetate or trifluoroacetate salt. Because the chain is short, the molecule is defined entirely by its residue order rather than by any folded three-dimensional structure.
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.
Hertz (1939), operations research scholar known for pioneering the Monte Carlo methods in finance Victor Wouk (1939), pioneer in the development of electric and hybrid vehicles Julius Ashkin (1940), nuclear physicist, brother of Arthur Ashkin '47 Jeremiah Stamler (1940), epidemiologist, expert in the field of preventive cardiology, professor emeritus at Northwestern University Ulrich P. Strauss (1941), chemist at Rutgers University, 1971 Guggenheim Fellow Bruce Wallace (1941), geneticist, professor at Virginia Tech Robert S. Wallerstein (1941), psychoanalyst and former president of the International Psychoanalytical Association and director of the Langley Porter Psychiatric Institute, brother of political scientist Immanuel Wallerstein '51 Kimball Chase Atwood III (1942), geneticist, professor at Columbia University Medical School Leon Davidson (1942), chemical engineer known for his work in the Manhattan Project and the study of Unidentified Flying Objects Karl Koopman (1943), chiropterologist and curator at the American Museum of Natural History Robert G.
== International accreditation == In 2007, Haim Hacham et al. published a paper addressing the need for and the process of international standardised accreditation for laboratory proficiency in Israel. With similar efforts, both the Japan Accreditation Board for Conformity Assessment (JAB) and the European Communities Confederation of Clinical Chemistry and Laboratory Medicine (EC4) have validated and convened ISO 15189 Medical laboratories — Requirements for quality and competence, respectively. In 2006, Spitzenberger and Edelhäuser expressed concerns that ISO accreditation may include obstacles arising from new emerging medical devices and the new approach of assessment; in so doing, they indicate the time dependence of standards.
To adopt a functional three-dimensional shape, the polypeptide chain must first form a series of smaller underlying structures called secondary structures. The polypeptide chain in these secondary structures then folds to produce the overall 3D tertiary structure. Once correctly folded, the protein can undergo further maturation through different post-translational modifications, which can alter the protein's ability to function, its location within the cell (e.g. cytoplasm or nucleus) and its ability to interact with other proteins. Protein biosynthesis has a key role in disease as changes and errors in this process, through underlying DNA mutations or protein misfolding, are often the underlying causes of a disease. DNA mutations change the subsequent mRNA sequence, which then alters the mRNA encoded amino acid sequence. Mutations can cause the polypeptide chain to be shorter by generating a stop sequence which causes early termination of translation. Alternatively, a mutation in the mRNA sequence changes the specific amino acid encoded at that position in the polypeptide chain. This amino acid change can impact the protein's ability to function or to fold correctly. Misfolded proteins have a tendency to form dense protein clumps, which are often implicated in diseases, particularly neurological disorders including Alzheimer's and Parkinson's disease.
Meiri (2022) questioned the reliability of the estimates, citing uncertainty in metabolic rate, body size, sex and age-specific survival rates, habitat requirements and range size variability as shortcomings Marshall et al. did not take into account. The authors of the original publication replied that while they agree that their reported uncertainties were probably too small, their framework is flexible enough to accommodate uncerainty in physiology, and that their calculations do not depend on short-term changes but rather on long-term averages. Finally, they remark that they did estimate the range of reasonable survivorship curves and that they did include uncertainty in the time of onset of sexual maturity and in the growth curve by incorporating the uncertainty in the maximum body mass.
Žarković, N.; Zarković, K.; Schaur, R. J. R.; Stolc, S.; Schlag, G. N.; Redl, H.; Waeg, G.; Borović, S.; Loncarić, I.; Jurić, G.; Hlavka, V. (1999). "4-Hydroxynonenal as a second messenger of free radicals and growth modifying factor". Life Sciences. 65 (18–19): 1901–1904. doi:10.1016/S0024-3205(99)00444-0. PMID 10576434. Sharma, R.; Brown, D.; Awasthi, S.; Yang, Y.; Sharma, A.; Patrick, B.; Saini, M. K.; Singh, S. P.; Zimniak, P.; Singh, S. V.; Awasthi, Y. C. (2004). "Transfection with 4-hydroxynonenal-metabolizing glutathione S-transferase isozymes leads to phenotypic transformation and immortalization of adherent cells". European Journal of Biochemistry. 271 (9): 1690–1701. doi:10.1111/j.1432-1033.2004.04067.x. PMID 15096208.
Sources: en.wikipedia.org
== The gastric ATPase == Acid secretion by the human stomach results in a median diurnal pH of 1.4. This very large (>106-fold) H+ gradient is generated by the gastric H+/K+ ATPase which is an ATP-driven proton pump. Hydrolysis of one ATP molecule is used to catalyse the electroneutral exchange of two luminal potassium ions for two cytoplasmic protons through the gastric membrane.
Al-Biruni (973–1050) wrote one of the most valuable Islamic works on pharmacology, entitled Kitab al-Saydalah (The Book of Drugs), in which he detailed the properties of drugs and outlined the role of pharmacy and the functions and duties of the pharmacist. Avicenna, too, described no less than 700 preparations, their properties, modes of action, and their indications. He devoted in fact a whole volume to simple drugs in The Canon of Medicine. Of great impact were also the works by al-Maridini of Baghdad and Cairo, and Ibn al-Wafid (1008–1074), both of which were printed in Latin more than fifty times, appearing as De Medicinis universalibus et particularibus by 'Mesue' the younger, and the Medicamentis simplicibus by 'Abenguefit'. Peter of Abano (1250–1316) translated and added a supplement to the work of al-Maridini under the title De Veneris. Al-Muwaffaq's contributions in the field are also pioneering. Living in the 10th century, he wrote The foundations of the true properties of Remedies, amongst others describing arsenious oxide, and being acquainted with silicic acid. He made clear distinction between sodium carbonate and potassium carbonate, and drew attention to the poisonous nature of copper compounds, especially copper vitriol, and also lead compounds. He also describes the distillation of sea-water for drinking. In Europe, pharmacy-like shops began to appear during the 12th century. In 1240, emperor Frederic II issued a decree by which the physician's and the apothecary's professions were separated.
Platelets or thrombocytes (from Ancient Greek θρόμβος (thrómbos) 'clot' and κύτος (kútos) 'cell') are a part of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping to form a blood clot. Platelets have no cell nucleus; they are fragments of cytoplasm from megakaryocytes which reside in bone marrow or lung tissue, and then enter the circulation. Platelets are found only in mammals, whereas in other vertebrates (e.g. birds, amphibians), thrombocytes circulate as intact mononuclear cells.
The stand-off cost three demonstrators their lives in clashes with the army on the night of 20–21 August before the coup leaders, lacking the broad military backing they needed and rapidly losing the fear that had sustained their authority, lost their nerve; Estonia and Latvia seized the moment to declare independence, and coup leader Boris Pugo took his own life rather than face arrest. Gorbachev formally resumed his powers on returning to Moscow, but by then the substance of power had already passed elsewhere—the Communist Party did not even condemn its own plotters until 21 August, by which point Yeltsin had exploited its paralysis to ban the Party outright within the Russian federation. Yeltsin's courage in personally defending the parliament building may have helped break the putsch but at the cost of Gorbachev's remaining authority.
== Bibliography == Baur, F. J.; Lange, W. (1951). "Directed Interesterification in Glycerides. III. The Synthesis of Single-Fatty Acid 1,3-Diglycerides". Journal of the American Chemical Society. 73 (8): 3926–3928. doi:10.1021/ja01152a109. Russell, Robert M.; Yeager, Robert; Baur, Fred; Dupre, James R. (November 1976). "Bird Problems and Food Storage and Processing Facilities". Bird Control Seminars Proceedings. Lincoln: University of Nebraska. Baur, F. J., ed. (1984). Insect Management for Food and Storage and Processing. St. Paul, Minnesota: American Association of Cereal Chemists. ISBN 0913250384. US patent US3498798A, Fredric J Baur, Harold Kenneth Hawley & Harold Kenneth Hawley, "Packaging of chip-type snack food products", published March 3, 1970, issued March 3, 1970, assigned to Procter and Gamble Co
Sources: en.wikipedia.org
== June 11, 1915 (Friday) == Second Battle of Artois — Despite the Germans inflicting major casualties, French advanced 500 metres (550 yd) on a 300-metre (330 yd) front towards Neuville-Saint-Vaast, France. Battle of Hébuterne — The German launched the first of two counterattacks, with the first failing to dislodge the French. Second Battle of Garua — British and French forces formally took control of all garrisons around Garua, German Cameroon. Friar Leonard Melki and hundreds of other Christians are driven out of Mardin and massacred by Ottoman troops. Born: Magda Gabor, Hungarian actress, eldest sister of the Gabor sisters which included Eva and Zsa Zsa; as Magdolna Gábor, in Budapest, Austria-Hungary (present-day Hungary) (d. 1997)
tissue In a multicellular organism, a contiguous aggregation of cells held together by a common extracellular matrix and specialized to perform a particular function. Some tissues are composed primarily of a single cell type; others are a heterogeneous mixture of many cell types. Tissues represent a level of multicellular organization between that of individual cells and that of organs, which may be composed of one or more distinct types of tissue.
Blue LEDs have an active region consisting of one or more InGaN quantum wells sandwiched between thicker layers of GaN, called cladding layers. By varying the relative In/Ga fraction in the InGaN quantum wells, the light emission can in theory be varied from violet to amber. Aluminium gallium nitride (AlGaN) of varying Al/Ga fraction can be used to manufacture the cladding and quantum well layers for ultraviolet LEDs, but these devices have not yet reached the level of efficiency and technological maturity of InGaN/GaN blue/green devices. If unalloyed GaN is used in this case to form the active quantum well layers, the device emits near-ultraviolet light with a peak wavelength centered around 365 nm. Green LEDs manufactured from the InGaN/GaN system are far more efficient and brighter than green LEDs produced with non-nitride material systems, but practical devices still exhibit efficiency too low for high-brightness applications. With AlGaN and AlGaInN, even shorter wavelengths are achievable. Near-UV emitters at wavelengths around 360–395 nm are already cheap and often encountered, for example, as black light lamp replacements for inspection of anti-counterfeiting UV watermarks in documents and bank notes, and for UV curing. Substantially more expensive, shorter-wavelength diodes are commercially available for wavelengths down to 240 nm. As the photosensitivity of microorganisms approximately matches the absorption spectrum of DNA, with a peak at about 260 nm, UV LED emitting at 250–270 nm are expected in prospective disinfection and sterilization devices.
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Sources: en.wikipedia.org
The solid is kept cold, dry and dark, typically at minus twenty degrees Celsius, in a sealed container with desiccant. Dissolved material is kept refrigerated and used promptly. Freezing and thawing a solution repeatedly is avoided because it accelerates degradation.
Reversed-phase chromatography with ultraviolet detection gives a purity percentage, while mass spectrometry confirms identity. Amino acid analysis checks the residue composition. Buyers typically request a certificate of analysis showing these measurements for the specific lot.
It is not authorised as a medicine in the United States or the European Union. Material is sold there as a research chemical or cosmetic ingredient. Some related short peptides are registered drugs in Russia, which is a distinct national situation rather than a general approval.
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.