If you have been reading about research chemical and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
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.
| 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 |
Analytical characterization of epitalon relies on standard peptide methods. Reverse-phase high-performance liquid chromatography is used to assess purity, and mass spectrometry confirms identity by checking the observed mass against the expected value near 390 daltons. Amino acid analysis can verify composition. Because the peptide is short and hydrophilic, it elutes early on many reverse-phase columns, so method development often requires ion-pairing reagents to achieve adequate retention and resolution from related impurities.
Storage and handling follow conventional peptide practice. Lyophilized epitalon is typically kept refrigerated or frozen, protected from moisture and light, and allowed to equilibrate to room temperature before opening to avoid condensation. Once dissolved, aqueous solutions are usually stored cold and used within a short period, since dilute peptide solutions can support microbial growth and may slowly degrade. The absence of cysteine and methionine reduces, but does not eliminate, oxidation concerns during long-term storage.
Regulatory status varies by country and is not harmonized. Epitalon is not an approved drug in major Western jurisdictions. In some countries it is sold as a research chemical, and in others it has appeared in products marketed for other categories. This inconsistent status means that purity, labeling accuracy, and documentation differ widely between suppliers, and verification of identity and purity through independent analysis is the usual way buyers assess a given lot.
Material supplied for laboratory use is normally a lyophilised white to off-white powder that dissolves readily in water and in isotonic saline. Lyophilised cakes are hygroscopic and should be equilibrated to room temperature before opening to limit condensation on the solid. Solutions are typically prepared at milligram-per-millilitre concentrations and divided into single-use aliquots, because repeated freeze–thaw cycles degrade short peptides. Aqueous solutions are far less stable than the dry powder, and identity is usually verified by mass spectrometry alongside purity estimation from reversed-phase high-performance liquid chromatography.
Epitalon is a synthetic linear tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and the calculated mass is approximately 390.35 g/mol. The compound is made by solid-phase peptide synthesis rather than extracted from tissue, although early work described it as a short fragment of a peptide fraction obtained from bovine pineal extract. In the research literature the spelling epitalon and the variant epithalone both appear, while AEDG is the standard code used in peptide nomenclature.
Several names circulate for the same molecule, including epitalon, epithalone, epithalamin tetrapeptide, and the sequence code AEDG. A CAS registry number, 307297-39-8, is commonly cited for it, though catalogue entries should be checked against supplier documentation because mislabelled records occur. In its usual form the peptide carries free amino and carboxyl termini and is neither glycosylated nor lipidated. Researchers distinguish the defined tetrapeptide from epithalamin itself, a crude pineal preparation containing many peptides that is not chemically characterised.
Animal and clinical reports appear mainly in Russian-language journals from the 1990s and 2000s, covering endpoints such as melatonin rhythm, lifespan in aged rodents, and retinal function. Many of these papers involve small groups, lack blinding or placebo comparison, and are difficult to retrieve through indexed databases. Review articles published in English generally summarise the claims without reanalysing the underlying data. Because no large randomised trial exists, the clinical importance of these reported effects stays unresolved and is properly described as an open question.
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.
Fluid dynamics is a subdiscipline of fluid mechanics that deals with fluid flow—the science of liquids and gases in motion. Fluid dynamics offers a systematic structure—which underlies these practical disciplines—that embraces empirical and semi-empirical laws derived from flow measurement and used to solve practical problems. The solution to a fluid dynamics problem typically involves calculating various properties of the fluid, such as velocity, pressure, density, and temperature, as functions of space and time. It has several subdisciplines itself, including aerodynamics (the study of air and other gases in motion) and hydrodynamics (the study of liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting evolving weather patterns, understanding nebulae in interstellar space and modeling explosions. Some fluid-dynamical principles are used in traffic engineering and crowd dynamics.
Wolfberries are most often sold in dried form. When ripe, the oblong, red berries are tender and must be picked or shaken from the vine into trays to avoid spoiling. The fruits are preserved by drying them in full sun on open trays or by mechanical dehydration, employing a progressively increasing series of heat exposure over 48 hours.
Tazarotene, sold under the brand name Tazorac, among others, is a third-generation prescription topical retinoid. It is primarily used for the treatment of plaque psoriasis and acne. Tazarotene is also used as a therapeutic for photoaged and photodamaged skin. It is a member of the acetylenic class of retinoids. Tazarotene was approved for medical use in 1997 and is available as a generic medication.
=== Iceland in 1986 === In 1986, at the age of 20, whilst at the University of Leeds, he crossed Iceland, together with three other students (Andrew Backhouse, David Brock and Shaun Fagan), from Seyðisfjörður in the east, through the interior to the north of the Vatnajökull ice fields, and then west to Reykjavík. The team encountered an 'ash storm', where storm force winds had whipped up fine black volcanic ash, and had to wear goggles and face masks to push on into the winds. In the rain shadow of the Vatnajökull, they ran out of water, then encountered a flash flood, as mud rushed down from the melting glaciers. They also had to survive on food contaminated with petrol that had leaked from their petrol stoves. This journey of 400 miles (640 km) raised £2,000 for the Royal Association for Disability and Rehabilitation. As part of the training for the walk across Iceland he ran the Leeds Marathon, in a time of 3 hours and 41 minutes. On the Icelandic trek, he came up with the idea of walking 6,000 miles (9,700 km), across Britain and America to raise money for Macmillan Cancer Support in Britain and hospice in America and Canada.
D* → D + hν For example, A could be luminol and B could be hydrogen peroxide. D would be 3-aminophthalate (3-APA). In theory, one photon of light should be given off for each molecule of reactant. In practice, the yield ("quantum efficiency") is often low owing to side reactions. Chemiluminescence differs from fluorescence or phosphorescence in that the electronic excited state is the product of a chemical reaction rather than of the absorption of a photon. It is the antithesis of a photochemical reaction, in which light is used to drive an endothermic chemical reaction. Instead, here light is generated from a chemically exothermic reaction. The chemiluminescence might be also induced by an electrochemical stimulus and in that case, it is called electrochemiluminescence.
Sources: en.wikipedia.org
=== Bacterial aminopeptidases === In bacteria, aminopeptidases are produced by both facultative anaerobic strains, which can respire with or without oxygen, and obligate strains, which either require or are killed by atmospheric oxygen. They and can be found in many different cellular locations, for example in the cytoplasm, in membranes, associated with the cell envelope, or secreted into the extracellular medium. These enzymes are involved in the breaking down of externally supplied peptides (very short proteins) and are necessary for the final steps of protein turnover and replacement. They also participate in specific functions like the cleavage of N-terminal (beginning) methionine from newly synthesized peptide chains (methionine aminopeptidases), stabilization of ColE1-based multicopy plasmids (e.g. aminopeptidase A), and the cleavage of N-terminal pyroglutamate (e.g. pyroglutamyl aminopeptidase.
Also in 1973, the "Percy Amendment" of the Foreign Assistance Act required U.S. development assistance to integrate women into its programs, leading to USAID's creation of its Women in Development (WID) office in 1974. The Helms Amendment of 1973 banned use of U.S. government funds for abortion as a method of family planning, which effectively required USAID to eliminate all support for abortion. A further amendment of the Foreign Assistance Act in 1974 prohibited assistance for police, thus ending USAID's involvement in Public Safety programs in Latin America, which in the 1960s were, along with the Vietnam War, part of the U.S. government's anti-Communist strategy. The reforms also ended the practice of the 1960s and 1970s in which many USAID officers in Latin America and Southeast Asia had worked in joint offices led by State Department diplomats or in units with U.S. military personnel. The Basic Human Needs reforms largely cut off USAID's assistance to higher education. A large part of that assistance had gone to agricultural universities in hungry developing countries, as illustrated by a 1974 book by a University of Illinois professor, Hadley Read, describing USAID-supported U.S. land-grant universities' work in building India's agricultural universities. Read's book inspired an Illinois Member of Congress concerned with famine prevention, Paul Findley, to draft a bill authorizing more support for programs like the ones Read described. In a legislative process involving USAID staff, the association of state universities and land-grant colleges (NASULGC), and Sen.
Aptamers are oligomers of artificial ssDNA, RNA, XNA, or peptide that bind a specific target molecule, or family of target molecules. They exhibit a range of affinities (KD in the pM to μM range), with variable levels of off-target binding and are sometimes classified as chemical antibodies. Aptamers and antibodies can be used in many of the same applications, but the nucleic acid-based structure of aptamers, which are mostly oligonucleotides, is very different from the amino acid-based structure of antibodies, which are proteins. This difference can make aptamers a better choice than antibodies for some purposes (see antibody replacement). Aptamers are used in biological lab research and medical tests. If multiple aptamers are combined into a single assay, they can measure large numbers of different proteins in a sample. They can be used to identify molecular markers of disease, or can function as drugs, drug delivery systems and controlled drug release systems. They also find use in other molecular engineering tasks. Most aptamers originate from SELEX, a family of test-tube experiments for finding useful aptamers in a massive pool of different DNA sequences. This process is much like natural selection, directed evolution or artificial selection. In SELEX, the researcher repeatedly selects for the best aptamers from a starting DNA library made of about a quadrillion different randomly generated pieces of DNA or RNA.
=== Androgen-dependent === Finasteride is a medication of the 5α-reductase inhibitors (5-ARIs) class. By inhibiting type II 5-AR, finasteride prevents the conversion of testosterone to dihydrotestosterone in various tissues including the scalp. Increased hair on the scalp can be seen within three months of starting finasteride treatment and longer-term studies have demonstrated increased hair on the scalp at 24 and 48 months with continued use. Treatment with finasteride more effectively treats male-pattern hair loss at the crown than male-pattern hair loss at the front of the head and temples. Dutasteride is a medication in the same class as finasteride but inhibits both type I and type II 5-alpha reductase. Dutasteride is approved for the treatment of male-pattern hair loss in Korea and Japan, but not in the United States. However, it is commonly used off-label to treat male-pattern hair loss.
=== EC 1.14.15 With reduced iron–sulfur protein as one donor, and incorporation of one atom of oxygen === EC 1.14.15.1: camphor 5-monooxygenase EC 1.14.15.2: Now EC 1.14.13.162, 2,5-diketocamphane 1,2-monooxygenase. EC 1.14.15.3: alkane 1-monooxygenase EC 1.14.15.4: steroid 11β-monooxygenase EC 1.14.15.5: corticosterone 18-monooxygenase EC 1.14.15.6: cholesterol monooxygenase (side-chain-cleaving) EC 1.14.15.7: choline monooxygenase EC 1.14.15.8: steroid 15β-monooxygenase EC 1.14.15.9: spheroidene monooxygenase EC 1.14.15.10: (+)-camphor 6-endo-hydroxylase EC 1.14.15.11: pentalenic acid synthase EC 1.14.15.12 : pimeloyl-[acyl-carrier protein] synthase.
Sources: en.wikipedia.org
Self-assembly is a scalable and parallel process which can involve large numbers of components in a short timeframe. Can result in structural dimensions across orders of magnitude, from nanoscale to macroscale. Is relatively inexpensive compared to the top-down assembly approach, which often consumes large amounts of finite resources. Natural processes that drive self-assembly tend to be highly reproducible. The existence of life is strongly dependent on the reproducibility of self-assembly. Challenges There exist several outstanding challenges in self-assembly, due to a variety of competing factors. Currently self-assembly is difficult to control on large scales, and to be widely applied we will need to ensure high degrees of reproducibility at these scales. The fundamental thermodynamic and kinetic mechanisms of self-assembly are poorly understood - the basic principles of atomistic and macroscale processes can be significantly different than those for nanostructures. Concepts related to thermal motion and capillary action influence equilibrium timescales and kinetic rates that are not well defined in self-assembling systems. Top-down vs bottom-up synthesis
In 2015, 251 million tubes of toothpaste were sold in the United States. A single tube holds roughly 170 grams of toothpaste, so approximately 43 kilotonnes of toothpaste get washed into the water systems annually. Toothpaste contains silver nanoparticles, also known as nanosilver or AgNPs, among other compounds. Each tube of toothpaste contains approximately 91 mg of silver nanoparticles, with approximately 3.9 tonnes of silver nanoparticles entering the environment annually. Silver nanoparticles are not entirely cleared from the water during the wastewater treatment process, possibly leading to detrimental environmental effects.
== Therapeutics targeting nonsense mutation diseases == Therapeutics for diseases caused by nonsense mutations attempt to recapitulate wild-type function by decreasing the efficacy of NMD, facilitating readthrough of the premature stop codon during translation, or editing the genomic nonsense mutation. Antisense oligonucleotides to suppress the expression of NMD and translation termination proteins are being explored in animal models of nonsense mutation-induced disease. Other RNA therapeutics under investigation include synthetic suppressor tRNAs that enable ribosomes to insert an amino acid, instead of initiating chain termination, upon encountering premature stop codons. CRISPR-Cas9 based single nucleotide substitutions have been used to generate amino acid codons from stop codons, achieving an editing success rate of 10% in cell cultures. Read-through has been achieved using small molecule drugs such as aminoglycosides and negamycin. An oxadiazole, ataluren (previously PTC124), facilitates the selective read-through of aberrant stop codons, rendering it a potential therapeutic against nonsense mutation-induced disease. Ataluren, sold under the tradename Translarna, is currently an approved treatment for Duchenne muscular dystrophy in the European Economic area and Brazil. However, phase III trials of Ataluren as a cystic fibrosis therapeutic have failed to meet their primary endpoints.
== Bibliography == Audi, G.; Kondev, F. G.; Wang, M.; et al. (2017). "The NUBASE2016 evaluation of nuclear properties". Chinese Physics C. 41 (3) 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001. Beiser, A. (2003). Concepts of modern physics (6th ed.). McGraw-Hill. ISBN 978-0-07-244848-1. OCLC 48965418. Hoffman, D. C.; Ghiorso, A.; Seaborg, G. T. (2000). The Transuranium People: The Inside Story. World Scientific. ISBN 978-1-78-326244-1. Kragh, H. (2018). From Transuranic to Superheavy Elements: A Story of Dispute and Creation. Springer. ISBN 978-3-319-75813-8. Silva, Robert J. (2011). "Chapter 13. Fermium, Mendelevium, Nobelium, and Lawrencium". In Morss, Lester R.; Edelstein, Norman M.; Fuger, Jean (eds.). The Chemistry of the Actinide and Transactinide Elements. Netherlands: Springer. doi:10.1007/978-94-007-0211-0_13. ISBN 978-94-007-0210-3. Zagrebaev, V.; Karpov, A.; Greiner, W. (2013). "Future of superheavy element research: Which nuclei could be synthesized within the next few years?". Journal of Physics: Conference Series. 420 (1) 012001. arXiv:1207.5700. Bibcode:2013JPhCS.420a2001Z. doi:10.1088/1742-6596/420/1/012001. ISSN 1742-6588. S2CID 55434734.
Neutral Protamine Hagedorn (NPH) insulin, also known as isophane insulin, is an intermediate-acting insulin given to help control blood sugar levels in people with diabetes. The words refer to neutral pH (pH = 7), protamine a protein, and Hans Christian Hagedorn, the insulin researcher who invented this formulation. It is designed to improve the delivery of insulin, and is one of the earliest examples of engineered drug delivery. It is used by injection under the skin once to twice a day. Onset of effects is typically in 90 minutes and they last for 24 hours. Versions are available that come premixed with a short-acting insulin, such as regular insulin. The common side effect is low blood sugar. Other side effects may include pain or skin changes at the sites of injection, low blood potassium, and allergic reactions. Use during pregnancy is relatively safe for the fetus. NPH insulin is made by mixing regular insulin and protamine in exact proportions with zinc and phenol such that a neutral-pH is maintained and crystals form. There are human and pig insulin based versions. Protamine insulin was first created in 1936 and NPH insulin in 1946. It is on the World Health Organization's List of Essential Medicines. NPH is an abbreviation for "neutral protamine Hagedorn". In 2020, insulin isophane was the 221st most commonly prescribed medication in the United States, with more than 2 million prescriptions. In 2020, the combination of human insulin with insulin isophane was the 246th most commonly prescribed medication in the United States, with more than 1 million prescriptions.
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.
Epitalon is a synthetic tetrapeptide composed of four amino acids: alanine, glutamate, aspartate, and glycine. It is written as Ala-Glu-Asp-Gly. The free peptide has a molecular weight of about 390 daltons and is normally supplied as a lyophilized powder.