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 2025-12-30. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Reported biological findings come mainly from cell culture and rodent experiments. Those studies describe changes in telomerase catalytic subunit expression, melatonin rhythm amplitude, and antioxidant enzyme activity after peptide exposure. Human data are sparse and consist of small trials with limited blinding and inconsistent endpoints. The proposed mechanisms remain hypotheses rather than established facts, and there is no consensus on whether effects observed in animals carry over to people. Independent replication outside the original research groups is limited, which is a recognised gap in the published literature.
The parent extract epithalamin was characterised as a low-molecular-weight fraction of pineal tissue rather than a single defined chemical entity. Researchers fractionated it and tested successive fragments for activity, a screening approach typical of peptide discovery work in that era. Epitalon emerged from that process as one of the shorter sequences of interest. Because the original extract was never fully resolved into individual components, claims about which constituent drives a given effect rest on inference. This distinction matters when reading older reports that attribute extract observations to the tetrapeptide itself.
The compound is generally described as a synthetic analogue of a fragment isolated from a pineal gland extract. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology introduced it during the 1980s and 1990s while studying short peptides from animal tissue. The original extract, called epithalamin, is a heterogeneous mixture, whereas epitalon is a single defined sequence. That distinction matters because findings reported for the extract are not automatically findings about the pure tetrapeptide, and claims about broader biological effects remain a separate question from the chemical identity described here.
Residue composition is the property that most cleanly separates verified material from mislabelled samples. Alanine, glutamate, aspartate and glycine appear in that order from the N-terminus, and the two acidic residues sit in the middle of the chain. Because the peptide is short, it can be produced by solid-phase synthesis and characterised by mass spectrometry without ambiguity. Any reported sample whose measured mass departs substantially from 390 daltons is a different compound or a degraded mixture rather than epitalon.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic tetrapeptide | Four amino acid residues |
| Residue sequence | Ala-Glu-Asp-Gly | Abbreviated AEDG |
| Approximate mass | 390.35 Da | Monoisotopic, free base form |
| Parent preparation | Epithalamin extract | Derived from pineal tissue |
| Common spelling variants | Epithalon, epithalone, AEDG | Affects literature retrieval |
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.
The published literature is dominated by a small number of research groups, much of it in Russian-language journals, and independent replication outside those groups is limited. Studies are typically small, use cultured cells or rodent models, and report endpoints that differ between papers, which makes comparison difficult. Large randomised human trials have not appeared in the indexed literature. Questions about absorption, distribution and clearance are therefore still treated as open in reviews that mention the compound.
Epitalon is a synthetic tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. Its design traces to epithalamin, a peptide fraction prepared from bovine pineal gland extracts that researchers in Saint Petersburg began investigating in the 1970s. The compound has a molecular formula of C14H22N4O9 and a nominal molecular mass near 390 daltons. It holds no approved drug status in the United States or the European Union, and material sold under this name is generally offered as a research chemical rather than a finished pharmaceutical product.
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.
The enzyme cystathionine γ-lyase (EC 4.4.1.1, CTH or CSE; also cystathionase; systematic name L-cystathionine cysteine-lyase (deaminating; 2-oxobutanoate-forming)) is an enzyme which in humans is encoded by the gene CTH. CTH enzymes break down cystathionine into cysteine, 2-oxobutanoate (α-ketobutyrate), and ammonia:
Thorium-232, which breeds uranium-233 by neutron capture with intermediate decays steps omitted. Uranium-238, which breeds plutonium-239 by neutron capture with intermediate decays steps omitted. Plutonium-240, which breeds plutonium-241 directly by neutron capture.
In addition, estradiol levels with estradiol patches are higher in the evening than in the morning, which may be due to circadian variations in skin blood flow that may influence absorption. In terms of area-under-the-curve levels of estradiol, the interindividual variability of transdermal estradiol has been found to be 20 to 44% using different transdermal formulations, and the intraindividual variability with transdermal estradiol has been found to be 20%. Factors which may contribute to inter- and intraindividual variability with transdermal estradiol include skin location and thickness; hair follicle density; solvent (alcohol) evaporation; skin dehydration, ambient temperature, and humidity; and reservoir size.
== Acceptable levels of consumption == The acceptable daily intake (ADI) value for food additives, including aspartame, is defined as the "amount of a food additive, expressed on a body weight basis, that can be ingested daily over a lifetime without appreciable health risk". The Joint FAO/WHO Expert Committee on Food Additives (JECFA) and the European Commission's Scientific Committee on Food (later becoming EFSA) have determined this value is 40 mg/kg of body weight per day for aspartame, while the FDA has set its ADI for aspartame at 50 mg/kg per day – an amount equated to consuming 75 packets of commercial aspartame sweetener per day to be within a safe upper limit. The primary source for exposure to aspartame in the US is diet soft drinks, though it can be consumed in other products, such as pharmaceutical preparations, fruit drinks, and chewing gum among others in smaller quantities. A 12-US-fluid-ounce (350 ml; 12 imp fl oz) can of diet soda contains 0.18 grams (0.0063 oz) of aspartame, and, for a 75-kilogram (165 lb) adult, it takes approximately 21 cans of diet soda daily to consume the 3.7 grams (0.13 oz) of aspartame that would surpass the FDA's 50 mg/kg of body weight ADI of aspartame from diet soda alone. Studies of aspartame consumption in the US, Europe, Australia and other countries have shown that even high levels of intake are well below the ADI for safe consumption.
Sources: en.wikipedia.org
== Limitations == Several limitations prevent heterologous expression to generate products at an economically feasible level that have been observed in bacteria, yeast, and plants. First, these methods are still extremely expensive compared to natural production, often take a longer time to generate, and require special conditions for host culture and induction of expression. Additionally, most methods have still not been optimized, with some even having lower expression than the native organism. Especially with biosynthetic genes for natural biologically active products of interest, researchers have discovered that they express very poorly in laboratory conditions, especially due to generally large gene sizes. Although protein products are produced, they are often generated at a very low yield, are poorly secreted due to low solubility, or produce other unwanted byproducts. Successful instances of heterologous production of target products are primarily seen with low-complexity genes with a small number of operons. This is often due to the mismatch in regulatory and expression induction pathways and machinery, and reflected in the observed degradation of certain amino acid sequences, decreased specific activity, incorrect membrane transportation, and glycosylation effects. Additionally, there are barriers during the translation process, where host tRNA effects reduce the efficiency of translation, specifically the recognition by host ribosomes.
=== Provincial government === Yasir Naqvi, the Attorney General of Ontario, and Eric Hoskins, the province's Minister of Health and Long-Term Care, jointly announced on the day of Wettlaufer's sentencing that the provincial government would commission a public inquiry into her case. The full details of the inquiry were not given in the announcement, as the government had yet to determine the scope or an individual to lead the inquiry, with Naqvi and Hoskins instead saying that the inquiry would "get the answers we need to help ensure a tragedy such as this does not happen again." The delay in establishing the inquiry was criticized by members of the opposition Progressive Conservative and New Democratic parties toward the end of July 2017, as no progress had seemingly been made since the announcement and the Legislative Assembly had risen for its summer recess. The Public Inquiry into the Safety and Security of Residents in the Long-Term Care Homes System was formally established by the provincial government on August 1, 2017. Justice Eileen Gillese of the Court of Appeal for Ontario was appointed commissioner of the inquiry. The inquiry was to include interviews with victims' families and public consultations in the community as it investigated the circumstances surrounding the deaths of Wettlaufer's victims and gaps in legislative or policy frameworks that allowed her to continue working as a nurse. The inquiry's lead counsel stated that "anyone from Wettlaufer to Premier Kathleen Wynne" may be called to testify before the inquiry based on the evidence that is uncovered.
=== EC 1.21.3 With oxygen as acceptor === EC 1.21.3.1: isopenicillin-N synthase EC 1.21.3.2: columbamine oxidase EC 1.21.3.3: reticuline oxidase EC 1.21.3.4: sulochrin oxidase ((+)-bisdechlorogeodin-forming) EC 1.21.3.5: sulochrin oxidase ((-)-bisdechlorogeodin-forming) EC 1.21.3.6: aureusidin synthase EC 1.21.3.7: tetrahydrocannabinolic acid synthase EC 1.21.3.8: cannabidiolic acid synthase EC 1.21.3.9: now classified as EC 1.21.98.2, dichlorochromopyrrolate synthase
== Structure == The body of the penis is suspended from the pubic symphysis by the suspensory ligament, part of the deep fascia arising from the anterior surface of the symphysis. It has two surfaces; the dorsal and the ventral or urethral. The penile raphe runs on its ventral surface. The body is surrounded by a bi-layered model of tunica albuginea in which a distal ligament buttresses the glans penis and plays an integral role in the penile fibroskeleton, and the structure is called "os analog", a term coined by Geng Long Hsu in the Encyclopedia of Reproduction. The human penis differs from those of most other mammals in having no baculum (or erectile bone), relying exclusively on engorgement with blood to reach its erect state; the loss of the baculum in the human lineage has been linked to changes in mating pattern. A shallow groove, which marks their junction on the upper surface lodges the deep dorsal vein of the penis, which is flanked by a pair of cavernosal veins of the penis, while a deeper and wider groove between them on the surface below contains the corpus spongiosum. The body is ensheathed by fascia, which includes tunica albuginea, Buck's fascia, dermis, and skin.
In the United States, Utah started screening for GAMT deficiency in all newborns in 2015. New York started screening newborns in late 2018. In 2020, a GAMT-positive infant was identified via newborn screening in Utah, thus providing evidence that a case could be identified from newborn screening. A second infant was identified in New York in 2021. In 2022, a federal advisory committee voted to include GAMT in the Recommended Universal Screening Panel starting in January 2023. In addition to New York and Utah, California, Pennsylvania, Connecticut, Delaware, and Michigan all currently screen for GAMT. Around the world, the state of Victoria, Australia began screening for GAMT in 2004, leading to the diagnosis of a newborn at birth in 2022. In Canada, the provinces of Ontario and British Columbia screen for GAMT.
Sources: en.wikipedia.org
It is based on epithalamin, a peptide-rich preparation obtained from pineal gland tissue and studied in the former Soviet Union. Researchers later identified the tetrapeptide AEDG as a constituent fragment of that material. Modern supplies are produced by chemical synthesis rather than tissue extraction.
No. Epithalamin is a heterogeneous extract containing many peptides, while epitalon is a single synthesised tetrapeptide. Publications sometimes treat findings from the two as equivalent, which is a common source of confusion. Their compositions differ and they are not interchangeable in analytical terms.
Most published work uses cell cultures or rodents because those models are faster and less costly to run. The few human trials that have been reported are small, and several lack control groups or blinding. This restricts what can reasonably be concluded about effects in people.
It is a four-amino-acid peptide built from alanine, glutamate, aspartate and glycine in that order. Its formula is C14H22N4O9, and it is made by chemical synthesis rather than extracted from tissue. The synthetic peptide is a single defined molecule, unlike the pineal extracts it is often compared with.