This is a working overview of counterion, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-03-11. Anything still debated is marked as such rather than presented as settled.
Solubility is high in water, phosphate-buffered saline and normal saline, a pattern that follows from the two acidic residues in the chain. The peptide dissolves poorly in non-polar solvents such as hexane or chloroform. Stock solutions are often prepared in water first and then diluted into the buffer of interest. Because the molecule is small and hydrophilic, filtration through a low-protein-binding membrane is usually straightforward, and visible particulates are uncommon in freshly made solutions.
Identity and purity are established with reversed-phase high-performance liquid chromatography and mass spectrometry. The chromatogram shows the main peak and any truncated or oxidised by-products, while the mass spectrum confirms the expected 390 dalton mass. Amino acid analysis can corroborate composition when a sample's origin is uncertain. Counterion content, particularly residual trifluoroacetate from purification, is frequently reported alongside purity because it shifts the net mass of the solid.
Epitalon is a synthetic tetrapeptide whose sequence is alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. It was developed in Russia during the 1980s and 1990s by investigators associated with the St. Petersburg Institute of Bioregulation and Gerontology, who studied short peptides as regulators of gene expression and tissue function. The alternative spelling epithalon appears interchangeably in the literature, and the two names refer to the same molecule. Outside Russia it is encountered chiefly as a research chemical rather than a licensed medicine, and it holds no approval from the United States Food and Drug Administration or the European Medicines Agency.
The peptide is a synthetic analogue of epithalamin, a preparation extracted from bovine pineal glands. Investigators sought a short, chemically defined molecule that would reproduce some of the endocrine and gerontological observations attributed to the glandular extract. Proposed mechanisms centre on induction of telomerase activity, an effect reported in cultured human somatic cells in the early 2000s, together with influences on melatonin secretion and neuroendocrine regulation. Those mechanisms remain incompletely characterised, and the reported telomerase response has not been consistently reproduced by independent groups working in comparable systems.
Published work on this compound consists mainly of in vitro experiments, animal studies, and small clinical investigations, a substantial share of which appeared in Russian-language journals. Sample sizes are generally small, control conditions differ between studies, and several endpoints rely on markers whose clinical meaning is itself debated. Reviews of the longevity field treat the peptide as an early example of telomerase-directed research rather than an established intervention. Regulatory treatment varies by country: some jurisdictions place it under prescription controls, others treat it as a laboratory material, and importation may be restricted regardless of local status.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised and often hygroscopic |
| Solubility class | Freely soluble in water | Poor solubility in non-polar solvents |
| Typical storage temperature | -20 degrees Celsius or colder | Sealed, desiccated, protected from light |
| Typical analytical method | Reversed-phase HPLC with mass spectrometry | Establishes purity and confirms mass |
| Common salt form | Trifluoroacetate or acetate | Counterion reported alongside purity values |
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.
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.
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.
The second method was known as "China blue" due to its resemblance to Chinese blue-and-white porcelain. Instead of using an indigo solution directly, the process involved printing the insoluble form of indigo onto the fabric. The indigo was then reduced in a sequence of baths of iron(II) sulfate, with air oxidation between each immersion. The China blue process could make sharp designs, but it could not produce the dark hues possible with the pencil blue method. Around 1880, the "glucose process" was developed. It finally enabled the direct printing of indigo onto fabric and could produce inexpensive dark indigo prints unattainable with the China blue method. Since 2004, freeze-dried indigo, or instant indigo, has become available. In this method, the indigo has already been reduced, and then freeze-dried into a crystal. The crystals are added to warm water to create the dye pot. As in a standard indigo dye pot, care has to be taken to avoid mixing in oxygen. Freeze-dried indigo is simple to use, and the crystals can be stored indefinitely as long as they are not exposed to moisture.
=== Toxicity === TTX is extremely toxic. The material safety data sheet for TTX lists the oral median lethal dose (LD50) for mice as 334 μg per kg. For comparison, the oral LD50 of potassium cyanide for mice is 8,500 μg per kg, demonstrating that even orally, TTX is more poisonous than cyanide. TTX is even more dangerous if administered intravenously; the amount needed to reach a lethal dose by injection is 8 μg per kg in mice. The toxin can enter the body of a victim by ingestion, injection, or inhalation, or through abraded skin. Poisoning occurring as a consequence of consumption of fish from the order Tetraodontiformes is extremely serious. The organs (e.g., liver) of the pufferfish can contain levels of tetrodotoxin sufficient to produce the described paralysis of the diaphragm and corresponding death due to respiratory failure. Toxicity varies between species and at different seasons and geographic localities, and the flesh of many pufferfish may not be dangerously toxic. The mechanism of toxicity is through the blockage of fast voltage-gated sodium channels, which are required for the normal transmission of signals between the body and brain. As a result, TTX causes loss of sensation, and paralysis of muscles including the diaphragm and intercostal muscles, stopping breathing.
The backbone of the DNA strand is made from alternating phosphate and sugar groups. The sugar in DNA is 2-deoxyribose, which is a pentose (five-carbon) sugar. The sugars are joined by phosphate groups that form phosphodiester bonds between the third and fifth carbon atoms of adjacent sugar rings. These are known as the 3′-end (three prime end), and 5′-end (five prime end) carbons, the prime symbol being used to distinguish these carbon atoms from those of the base to which the deoxyribose forms a glycosidic bond. Therefore, any DNA strand normally has one end at which there is a phosphate group attached to the 5′ carbon of a ribose (the 5′ phosphoryl) and another end at which there is a free hydroxyl group attached to the 3′ carbon of a ribose (the 3′ hydroxyl). The orientation of the 3′ and 5′ carbons along the sugar-phosphate backbone confers directionality (sometimes called polarity) to each DNA strand. In a nucleic acid double helix, the direction of the nucleotides in one strand is opposite to their direction in the other strand: the strands are antiparallel. The asymmetric ends of DNA strands are said to have a directionality of five prime end (5′ ), and three prime end (3′), with the 5′ end having a terminal phosphate group and the 3′ end a terminal hydroxyl group. One major difference between DNA and RNA is the sugar, with the 2-deoxyribose in DNA being replaced by the related pentose sugar ribose in RNA.
Sources: en.wikipedia.org
Melanocortin receptors are members of the rhodopsin family of 7-transmembrane G protein-coupled receptors. There are five known members of the melanocortin receptor system each with differing specificities for melanocortins:
=== 20th century === Elly Agallidis (1914–2006), Greek physical chemist Nancy Allbritton, American analytical and biochemist Marianne Angermann (1904-1977), German-Spanish-New Zealand biochemist Valerie Ashby, American chemist Barbara Askins (born 1939), American chemist Kim K. Baldridge, American computational chemist Alice Ball (1892–1916), American chemist Carolyn Bertozzi (born 1966), American biochemist Cynthia Burrows, American physical organic chemist Asima Chatterjee (1917–2006), Indian organic chemist Ecaterina Ciorănescu-Nenițescu (1909–2000), Romanian chemist Astrid Cleve (1875–1968), Swedish chemist Mildred Cohn (1913–2009), American chemist Janine Cossy (born 1950), French organic chemist Maria Skłodowska-Curie (1867–1934), Polish-French physicist and chemist (discoverer of polonium and radium, pioneer in radiology); Nobel laureate in physics 1903, and in chemistry 1911 Jillian Lee Dempsey (born 1983), American chemist Vy M. Dong, American organic chemist Abigail Doyle (born 1980), American organic chemist Odile Eisenstein (born 1949), French, theoretical chemist Gertrude B. Elion (1918–1999), American biochemist (Nobel prize in Physiology or Medicine 1988 for drug development) Margaret Faul, Irish/American organic chemist Mary Peters Fieser (1909–1997), American organic chemist Marye Anne Fox (1947–2021), American physical organic chemist Rosalind Franklin (1920–1957), British physical chemist and crystallographer Helen Murray Free (1923–2021), American chemist Gunda I.
== Clinical use == The most frequent use of aminoglycosides is empiric therapy for serious infections such as sepsis, complicated intra-abdominal infections, complicated urinary tract infections, and nosocomial respiratory tract infections. Usually, once cultures of the causal organism are grown and their susceptibilities tested, aminoglycosides are discontinued in favor of less toxic antibiotics. The recent emergence of infections due to Gram-negative bacterial strains with advanced patterns of antimicrobial resistance has prompted physicians to reevaluate the use of these antibacterial agents. This revived interest in the use of aminoglycosides has brought back to light the debate on the two major issues related to these compounds, namely the spectrum of antimicrobial susceptibility and toxicity. Current evidence shows that aminoglycosides do retain activity against the majority of Gram-negative clinical bacterial isolates in many parts of the world. Still, the relatively frequent occurrence of nephrotoxicity and ototoxicity during aminoglycoside treatment makes physicians reluctant to use these compounds in everyday practice. Recent advances in the understanding of the effect of various dosage schedules of aminoglycosides on toxicity have provided a partial solution to this problem, although more research still needs to be done in order to overcome this problem entirely.
Immune-mediated causes could include transient factors as in Mycoplasma pneumoniae infection (cold agglutinin disease) or permanent factors as in autoimmune diseases like autoimmune hemolytic anemia (itself more common in diseases such as systemic lupus erythematosus, rheumatoid arthritis, Hodgkin's lymphoma, and chronic lymphocytic leukemia). Spur cell hemolytic anemia Any of the causes of hypersplenism (increased activity of the spleen), such as portal hypertension. Acquired hemolytic anemia is also encountered in burns and as a result of certain infections (e.g. malaria). Lead poisoning or poisoning by arsine or stibine causes non-immune hemolytic anemia. Runners can develop hemolytic anemia due to "footstrike hemolysis", the destruction of red blood cells in feet at foot impact. Low-grade hemolytic anemia occurs in 70% of prosthetic heart valve recipients, and severe hemolytic anemia occurs in 3%.
Sources: en.wikipedia.org
Sealed lyophilised powder is normally kept at minus twenty degrees Celsius or below, away from light and moisture. Vials are allowed to reach room temperature before opening to limit condensation. Repeated warming and cooling of the same vial is discouraged.
Reversed-phase HPLC establishes purity and separation from related peptides, and mass spectrometry confirms the molecular mass. Amino acid analysis can verify residue composition. No single method proves identity on its own, so the results are read together.
Yes. Residual trifluoroacetate or acetate from purification adds mass and can shift the value obtained by certain assays. Purity figures are therefore meaningful only when the counterion form is stated. Reporting both peptide content and salt form gives a clearer picture.
Epitalon is a synthetic four-amino-acid peptide with the sequence alanine–glutamate–aspartate–glycine, also written AEDG. It was developed in Russian gerontology research and is studied for proposed effects on telomerase, melatonin regulation, and neuroendocrine function. It is not an approved pharmaceutical in the United States or the European Union.