If you have been reading about tetrapeptide 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 2025-12-20. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Dissolution is usually performed in water or a suitable aqueous buffer, and the resulting liquid is divided into single-use portions before freezing. Freeze-thaw cycling is a recognised source of loss for short peptides, since each cycle can encourage aggregation or adsorption onto container walls. Working solutions are generally kept cold and used within a short window, although published stability data specific to epitalon are thin. Containers should be marked with concentration and date, and solutions examined for cloudiness before use.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Calculated from the four residues with three water losses |
| Molecular mass | About 390.35 g/mol | Monoisotopic mass near 390.14, used for mass-spectrometric identification |
| Peptide sequence | Ala-Glu-Asp-Gly | Single-letter form AEDG; no disulfide bonds or modified residues |
| Appearance | White to off-white solid | Supplied as a dried powder |
| Isoelectric point | Around 4 | Estimated from aspartate and glutamate side-chain pKa values |
Storage recommendations center on limiting moisture, heat, and light. The dry powder is generally kept at minus 20 degrees Celsius, and some suppliers recommend minus 80 degrees for long-term archival. Once dissolved, solutions are usually aliquoted and frozen to avoid repeated freeze-thaw cycles, which can promote aggregation or degradation. Aqueous stability depends on pH and concentration, and buffered saline is often preferred over plain water for biological work. Stability data specific to epitalon remain limited, so general peptide-handling practices are applied by analogy rather than from product-specific validation.
Epitalon is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and its calculated monoisotopic mass is approximately 390.35 daltons. The compound does not occur naturally as a free peptide; it is produced by solid-phase peptide synthesis. Because it contains two acidic residues and no basic residues, the neutral form carries a net negative charge at physiological pH. This charge profile influences how the peptide behaves in solution and during chromatographic analysis.
Lyophilised epitalon is generally held at minus twenty degrees Celsius in a sealed container kept dry and dark. Cooler conditions are sometimes recommended for long-term archives. The solid takes up moisture readily enough that repeated opening of a vial introduces water, so dividing a batch into smaller portions before storage lowers degradation risk. Aqueous solutions are less durable than the dry powder and are usually prepared shortly before use, then kept cold and shielded from light to slow hydrolysis and oxidation.
Verification of research-grade material involves comparing a supplier chromatogram against an in-house reference, checking the observed mass against the calculated value, and where possible confirming residue order by tandem mass spectrometry or enzymatic peptide mapping. Purity claims should be read alongside the method used to obtain them, because detection wavelength and integration settings alter the result. Batch-specific data, rather than a generic grade statement, is the informative part of a certificate.
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.
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.
== Chemistry == Icodextrin is a starch-derived, branched, water-soluble glucose polymer linked by α-(1→4) and less than 10% α-(1→6) glycosidic bonds, making it a type of dextrin. Its weight-average molecular weight is between 13,000 and 19,000 daltons and its number-average molecular weight between 5,000 and 6,500 daltons. The substance is a white to off-white solid, and the solution is clear and colourless to pale yellow.
Difloxacin (INN), marketed under the trade name Dicural, is a second-generation, synthetic fluoroquinolone antibiotic used in veterinary medicine. It has broad-spectrum, concentration dependent, bactericidal activity; however, its efficacy is not as good as enrofloxacin or pradofloxacin.
=== Toxicity === Acetonitrile has only modest toxicity in small doses. It can be metabolised to produce hydrogen cyanide, which is the source of the observed toxic effects. Generally the onset of toxic effects is delayed, due to the time required for the body to metabolize acetonitrile to cyanide (generally about 2–12 hours). Cases of acetonitrile poisoning in humans are rare but not unknown by inhalation and ingestion. The symptoms, which do not usually appear for several hours after the exposure, include breathing difficulties, slow pulse rate, nausea, and vomiting. Convulsions and coma can occur in serious cases, followed by death from respiratory failure. The treatment is as for cyanide poisoning, with oxygen, sodium nitrite, and sodium thiosulfate among the most commonly used emergency treatments. It has been used in a formulation for removal of sculptured fingernails. At least two cases have been reported of accidental poisoning of young children by acetonitrile-based sculptured nail remover, one of which was fatal. Acetone and ethyl acetate are often preferred as safer for domestic use, and acetonitrile has been banned in cosmetic products in the European Economic Area since March 2000.
These estimates are measured by examining how a ligand binds to a receptor while simultaneously reacting to a substitute agent (antagonist) that will prevent specific binding to occur. Specific binding types to ligand and receptor interactions:
Sources: en.wikipedia.org
==== Tryptamine and lysergamide psychedelics ==== Austrian anthropologist and ethnobotanist Blas Pablo Reko, traveling through Central and South America, wrote of the use of teonanacatl by native Mexican people in Oaxaca in 1919. Reko subsequently sent samples of teonanacatl (Psilocybe mexicana) as well as Ipomoea violacea (morning glory) seeds to Swedish anthropologist Henry Wassén in 1937. Reko had obtained the mushroom sample from Austrian engineer Robert Weitlaner who was working in Mexico. Eventually, Wassén forwarded Reko and Weitlaner's mushroom sample to Harvard University, where the mushrooms came to the attention of American ethnobotanist Richard Evans Schultes. However, they had decomposed so badly that they could not be identified. Prior to Wassén obtaining specimens around 1936, the existence of teonanacatl was very controversial and was debated and even denied by some. In 1938, a small group of Westerners, which included Weitlaner's daughter and American anthropologist Jean Basset Johnson, attended a mushroom ceremony. They were the first Westerners known to do so and described the event. Schultes published reviews of teonanacatl being a hallucinogenic mushroom in the late 1930s. Schultes obtained specimens of three of the hallucinogenic mushrooms used in ceremonies, including Psilocybe caerulescens, Panaeolus campanulatus, and Stropharia cubensis, but further investigations of the mushrooms were interrupted by World War II.
Liquid carbon dioxide forms only at pressures above 0.51795(10) MPa (5.11177(99) atm); the triple point of carbon dioxide is 216.592(3) K (−56.558(3) °C) at 0.51795(10) MPa (5.11177(99) atm) (see phase diagram). The critical point is 304.128(15) K (30.978(15) °C) at 7.3773(30) MPa (72.808(30) atm). Another form of solid carbon dioxide observed at high pressure is an amorphous glass-like solid. This form of glass, called carbonia, is produced by supercooling heated CO2 at extreme pressures (40–48 GPa, or about 400,000 atmospheres) in a diamond anvil. This discovery confirmed the theory that carbon dioxide could exist in a glass state similar to other members of its elemental family, like silicon dioxide (silica glass) and germanium dioxide. Unlike silica and germania glasses, however, carbonia glass is not stable at normal pressures and reverts to gas when pressure is released. At temperatures and pressures above the critical point, carbon dioxide behaves as a supercritical fluid known as supercritical carbon dioxide.
=== Others === Syringes are used to refill ink in fountain pens and printer ink cartridges. Common workshop applications include injecting glue into tight spots to repair joints where disassembly is impractical or impossible; and injecting lubricants onto working surfaces without spilling. Sometimes a large hypodermic syringe is used without a needle for very small baby mammals to suckle from in artificial rearing. Historically, large pumps that use reciprocating motion to pump water were referred to as syringes. Pumps of this type were used as early firefighting equipment. There are fountain syringes where the liquid is in a bag or can and goes to the nozzle via a pipe. In earlier times, clyster syringes were used for that purpose. Loose snus is often applied using modified syringes. The nozzle is removed so the opening is the width of the chamber. The snus can be packed tightly into the chamber and plunged into the upper lip. Syringes, called portioners, are also manufactured for this particular purpose.
==== Dietary recommendations ==== The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for zinc in 2001. The current EARs for zinc for women and men ages 14 and up is 6.8 and 9.4 mg/day, respectively. The RDAs are 8 and 11 mg/day. RDAs are higher than EARs so as to identify amounts that will cover people with higher than average requirements. RDA for pregnancy is 11 mg/day. RDA for lactation is 12 mg/day. For infants up to 12 months the RDA is 3 mg/day. For children ages 1–13 years the RDA increases with age from 3 to 8 mg/day. As for safety, the IOM sets Tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of zinc the adult UL is 40 mg/day including both food and supplements combined (lower for children). Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes (DRIs). The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL are defined the same as in the United States. For people ages 18 and older the PRI calculations are complex, as the EFSA has set higher and higher values as the phytate content of the diet increases. For women, PRIs increase from 7.5 to 12.7 mg/day as phytate intake increases from 300 to 1200 mg/day; for men the range is 9.4 to 16.3 mg/day. These PRIs are higher than the U.S. RDAs.
Birds have featured in culture and art since prehistoric times, when they were represented in early cave painting and carvings. Some birds have been perceived as monsters, including the mythological Roc and the Māori's legendary Pouākai, a giant bird capable of snatching humans. Birds were later used as symbols of power, as in the magnificent Peacock Throne of the Mughal and Persian emperors. With the advent of scientific interest in birds, many paintings of birds were commissioned for books. Among the most famous of these bird artists was John James Audubon, whose paintings of North American birds were a great commercial success in Europe and who later lent his name to the National Audubon Society. Birds are also important figures in poetry; for example, Homer incorporated nightingales into his Odyssey, and Catullus used a sparrow as an erotic symbol in his Catullus 2. The relationship between an albatross and a sailor is the central theme of Samuel Taylor Coleridge's The Rime of the Ancient Mariner, which led to the use of the term as a metaphor for a 'burden'. Other English metaphors derive from birds; vulture funds and vulture investors, for instance, take their name from the scavenging vulture. Aircraft, particularly military aircraft, are frequently named after birds. The predatory nature of raptors make them popular choices for fighter aircraft such as the F-16 Fighting Falcon and the Harrier Jump Jet, while the names of seabirds may be chosen for aircraft primarily used by naval forces such as the HU-16 Albatross and the V-22 Osprey.
Sources: en.wikipedia.org
== Nomenclature == The first member of this gene family was called p10, in reference to the size and molecular weight (in kDa) of a protein from insect regenerating legs. The same protein (called Pam) was found in the adult antennae and legs from the two sexes of the American cockroach P. americana [2, 35]. Similar clones identified in Drosophila and Locusta in a search for olfactory genes referred to Olfactory-Sensory type D protein (OS-D or Pheromone Binding Protein A10) [20, 46-47]. Related clones identified in the antennae of the sphingid Manduca sexta were named sensory appendage proteins (SAPs) to distinguish them from a family of longer six-cysteine soluble proteins, i.e. odorant-binding proteins or OBPs [48]. Individual SAPs/CSPs have been designated in various ways: p10/Periplaneta americana (Nomura et al., 1992) [35], A10/Drosophila melanogaster (Pikielny et al., 1994) [46], OS-D/D. melanogaster (McKenna et al., 1994) [47], Pam/P. americana (Picimbon & Leal, 1999) [2], CSP/Schistocerca gregaria (Angeli et al., 1999) [3], SAP/Manduca sexta (Robertson et al., 1999) [48], Pherokine/D. melanogaster (Sabatier et al., 2003) [33], B-CSP/Acinetobacter baumannii, Macrococcus caseolyticus, Kitasatospora griseola, Escherichia coli (Liu et al., 2019) [24]. The protein family was renamed to chemosensory protein (CSP) by Angeli et al. after one (polyclonal) antibody against p10 labeled some sensory structures in the adult antennae of the desert locust Schistocerca gregaria [3]. The term “B-CSP” was used to refer to similar clones from bacterial (B) species [24].
== Biochemistry == Androgens like testosterone are responsible for penis enlargement and elongation during puberty. Penis size is positively correlated with increasing testosterone levels during puberty. But after puberty, administration of testosterone does not affect penis size, and androgen deficiency in adult men only results in a small decrease in size. Growth hormone (GH) and insulin-like growth factor 1 (IGF-1) are also involved in penis size, with deficiency (such as that observed in growth hormone deficiency or Laron syndrome) at critical developmental stages having the potential to result in micropenis.
The first woman elected president of a country was Vigdís Finnbogadóttir of Iceland, who won the 1980 presidential election as well as three subsequent elections, remaining in office for a total of 16 years, which makes her the longest-serving non-hereditary female head of state in history. Vigdís was also the first woman to win a presidential election where the second place candidate was another woman: she defeated Sigrún Þorsteinsdóttir in the 1988 presidential election. The first democratically elected female prime minister of a Muslim majority country was Benazir Bhutto of Pakistan, who led her party to victory in the 1988 general election and later in 1993, making her the first woman democratically elected leader of any Muslim nation. Bhutto was also the first of only two non-hereditary female world leaders who gave birth to a child while serving in office, the other being Jacinda Ardern of New Zealand. The longest-tenured female non-hereditary head of government is Sheikh Hasina of Bangladesh. She served as the country's prime minister from June 1996 to July 2001 and again from January 2009 until August 2024, for a combined total of over 20 years. Finland was the first republic in which women served concurrently as both the head of state and head of government, with both Anneli Jäätteenmäki and Mari Kiviniemi serving as prime ministers under president Tarja Halonen.
The reaction involves adsorption of protons onto S8 clusters, followed by disproportionation into the reaction products. The second, fourth and sixth ionization energies of sulfur are 2252 kJ/mol, 4556 kJ/mol and 8495.8 kJ/mol, respectively. The composition of reaction products of sulfur with oxidants (and its oxidation state) depends on whether releasing of reaction energy overcomes these thresholds. Applying catalysts and/or supply of external energy may vary sulfur's oxidation state and the composition of reaction products. While reaction between sulfur and oxygen under normal conditions gives sulfur dioxide (oxidation state +4), formation of sulfur trioxide (oxidation state +6) requires a temperature of 400–600 °C (750–1,100 °F) and presence of a catalyst. In reactions with elements of lesser electronegativity, it reacts as an oxidant and forms sulfides, where it has oxidation state −2. Sulfur reacts with nearly all other elements except noble gases, even with the notoriously unreactive metal iridium (yielding iridium disulfide). Some of those reactions require elevated temperatures.
Sources: en.wikipedia.org
No. Epithalamin is a peptide-containing extract of bovine pineal glands, while epitalon is a single synthetic tetrapeptide. The extract contains many peptides and other tissue components, so its composition varies between batches in ways that a synthesised sequence does not.
It is not recognised as an endogenous peptide hormone. The four-residue sequence can appear inside larger proteins and in digestive fragments of dietary protein, but no dedicated pathway producing it as a signalling molecule has been identified.
Several cell-culture reports describe increased telomerase activity after treatment, measured by enzyme assays or by transcript levels. Results differ between cell types and laboratories, and measured telomere lengthening has been reported in some studies but not in others, which leaves the physiological relevance open.
Reversed-phase high-performance liquid chromatography is run alongside mass spectrometry. The chromatogram separates components and gives a purity figure, while the mass spectrum confirms that the measured molecular mass matches the expected sequence. Neither measurement on its own is treated as sufficient.