tetrapeptide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-02-12. Where a claim depends on a specific study, the study is described rather than over-claimed.
Laboratory handling begins with dissolution of the lyophilized powder in water or a suitable aqueous buffer. The dry solid is the more stable form, so stock solutions are generally prepared only when required and kept cold afterwards. Repeated freezing and thawing of a solution is avoided because it encourages aggregation and gradual loss of the intact chain. Diluents and containers are selected to limit adsorption of a short peptide onto plastic surfaces and to reduce microbial growth in aqueous preparations.
Stability depends strongly on pH, temperature and the presence of oxygen and trace metals. Cleavage of the backbone proceeds faster under neutral to alkaline conditions, whereas acidic solutions tend to slow that reaction. The aspartate and glutamate side chains can undergo deamidation or imide formation over time, generating closely related impurities. Published stability data specific to epitalon are sparse, so the usable life of a given solution is best regarded as an open question that depends on buffer composition, concentration and storage temperature.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography with ultraviolet detection, frequently near 214 nanometers where the peptide bond absorbs. Mass spectrometry, most often with electrospray ionization, confirms the observed molecular mass and helps separate the intact peptide from truncated or modified forms. Amino acid analysis or tandem mass spectrometry can establish residue order. Purity is commonly quoted as an area percentage, yet such values are method-dependent, and comparisons between laboratories require matching column, gradient and detection wavelength.
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.
| Property | Value | Notes |
|---|---|---|
| Storage temperature, dry powder | -20 degrees Celsius or lower | Sealed, dark, low humidity |
| Storage temperature, solution | 2 to 8 degrees Celsius | Short-term use expected |
| Primary purity method | Reversed-phase HPLC | Ultraviolet detection near 214 nm |
| Identity confirmation | Electrospray mass spectrometry | Compared with calculated mass |
| Typical purity specification | Area percent of 95 or higher | Depends on column and gradient |
The most widely cited claim is that epitalon activates telomerase and thereby extends telomere length. Supporting evidence comes largely from cultured human cells, where treatment was associated with increased telomerase activity and delayed replicative senescence. Telomerase activation is a biologically consequential effect, since the enzyme is largely silenced in most somatic cells. However, the route by which a short peptide would reach and act on the enzyme's regulatory machinery has not been established. Independent replication in human trials is scarce, so the link between cell-culture observations and whole-body aging remains an open question.
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.
Most experimental work has been carried out in cell culture and animal models. Several reports describe changes in telomerase activity and proliferation in cultured cells, while rodent studies have examined lifespan, melatonin rhythm and reproductive endpoints. Human data remain limited, and much of the published clinical material consists of small trials with incomplete reporting of methods and controls. Whether the cell and animal findings translate into measurable effects in people is an open question, and the mechanistic basis of the reported telomerase changes is not fully established.
Discussions in the literature often conflate three distinct entities: the pineal extract epithalamin, the isolated tetrapeptide AEDG, and commercial preparations sold under similar names. Reviews citing older Russian-language studies sometimes omit detail on purity, route of administration and control groups, which makes cross-study comparison difficult. Researchers working with the compound generally note the need for independent replication, standardized enzyme assays, and clearer reporting of peptide identity. These caveats are relevant when weighing claims that appear in secondary sources rather than in primary reports.
（TG:@pojiaai）Epitalon is a synthetic linear tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, abbreviated AEDG. It emerged from work on epithalamin, a peptide fraction prepared from bovine pineal tissue, and was designed as a short, chemically defined analogue of that extract. Early publications came mainly from Russian laboratories studying pineal peptides and aging-related endpoints. The compound appears in the literature under several spellings, including epithalon and epithalone, which complicates systematic searching. Its small size makes solid-phase assembly and routine analytical characterization straightforward.
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.
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In 1992, DiCaprio had a brief role in the first installment of the Poison Ivy film series, and was handpicked by Robert De Niro from a shortlist of 400 young actors to co-star with him in This Boy's Life. Adapted from the memoir by Tobias Wolff, the film focuses on the relationship between a rebellious teenager, Toby (DiCaprio), and his mother (Ellen Barkin) and abusive stepfather (De Niro). Director Michael Caton-Jones said that DiCaprio did not know how to behave on set; accordingly, Caton-Jones used a strict mentoring style, after which DiCaprio's behavior began to improve. Bilge Ebiri of Rolling Stone found that the powerful bond between Barkin and DiCaprio elevated the film, praising DiCaprio's portrayal of his character's complex growth from a rebellious teen to an independent young man. This Boy's Life was the first film that gained him recognition. DiCaprio's first talk show appearance was in 1992 on the Looseleaf Report, hosted by Victoria Looseleaf, who later wrote a 1998 (unauthorized) biography on him. DiCaprio played the developmentally disabled brother of Johnny Depp's character in What's Eating Gilbert Grape (1993), a comedy-drama about a dysfunctional Iowa family. Caton-Jones recommended DiCaprio to director Lasse Hallström who was initially skeptical, as he considered DiCaprio too good-looking for the part. Hallström cast DiCaprio after he emerged as "the most observant" auditionee.
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Sources: en.wikipedia.org
Penicillin kills bacteria by inhibiting the completion of the synthesis of peptidoglycans, the structural component of the bacterial cell wall. It specifically inhibits the activity of enzymes that are needed for the cross-linking of peptidoglycans during the final step in cell wall biosynthesis. It does this by binding to penicillin binding proteins with the β-lactam ring, a structure found on penicillin molecules. This causes the cell wall to weaken due to fewer cross-links and means water uncontrollably flows into the cell because it cannot maintain the correct osmotic gradient. This results in cell lysis and death. Bacteria constantly remodel their peptidoglycan cell walls, simultaneously building and breaking down portions of the cell wall as they grow and divide. During the last stages of peptidoglycan biosynthesis, uridine diphosphate-N-acetylmuramic acid pentapeptide (UDP-MurNAc) is formed in which the fourth and fifth amino acids are both D-alanyl-D-alanine. The transfer of D-alanine is done (catalysed) by the enzyme DD-transpeptidase (penicillin-binding proteins are such type). The structural integrity of bacterial cell wall depends on the cross linking of UDP-MurNAc and N-acetyl glucosamine. Penicillin and other β-lactam antibiotics act as an analogue of D-alanine-D-alanine (the dipeptide) in UDP-MurNAc owing to conformational similarities. The DD-transpeptidase then binds the four-membered β-lactam ring of penicillin instead of UDP-MurNAc.
As Deka Yellow, Jasmine wields the D-Knuckle and the D-Stick (ディースティック, Dī Sutikku) jitte, which can combine to form the D-Shot (ディーショット, Dī Shotto) handgun and allow her to perform the Twin Cam Shot (ツインカムショット, Tsuin Kamu Shotto) attack alongside Umeko. Using the SP License, she can perform the Mirage Dimension (ミラージュディメンション, Mirāju Dimenshon) attack. Jasmine is portrayed by Ayumi Kinoshita (木下 あゆ美, Kinoshita Ayumi). As a child, she is portrayed by Risa Asagi (浅黄 理紗, Asagi Risa).
=== Legal status === In May 2026, the Committee for Medicinal Products for Human Use of the European Medicines Agency adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Ablymico, indicated for weight management as an adjunct to a reduced-calorie diet and increased physical activity. The applicant for this medicinal product is STADA Arzneimittel AG. Ablymico is a hybrid medicine of liraglutide (Saxenda), which has been authorized in the European Union since March 2015. Ablymico contains the same active substance as Saxenda, but it is chemically synthesized, whereas the active substance in the reference products is of biological origin. Ablymico was authorized for medical use in the European Union in July 2026. In May 2026, the CHMP adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Liraglutide Stada, intended for the treatment of insufficiently controlled type 2 diabetes. The applicant for this medicinal product is STADA Arzneimittel AG. Liraglutide Stada is a hybrid medicine of liraglutide (Victoza), which has been authorized in the European Union since June 2009. Liraglutide Stada contains the same active substance as Victoza, but it is chemically synthesized, whereas the active substance in the reference products is of biological origin.
=== Category:EC 1.7 (act on other nitrogenous compounds as donors) === Category:EC 1.7.1 (with NAD+ or NADP+ as acceptor) Category:EC 1.7.2 (with a cytochrome as acceptor) Category:EC 1.7.3 (with oxygen as acceptor) Urate oxidase EC 1.7.3.3 Category:EC 1.7.7 (with an iron–sulfur protein as acceptor) Category:EC 1.7.99 (with other acceptors) Nitrite reductase EC 1.7.99.3 Nitrate reductase EC 1.7.99.4
Sources: en.wikipedia.org
The dry powder is typically held at -20 degrees Celsius or lower, protected from light and moisture. Allowing a sealed vial to reach room temperature before opening reduces condensation on its contents. Conditions stated on a supplier certificate of analysis take precedence over general guidance.
Mass spectrometry supplies an observed molecular mass that is compared with the calculated value for the tetrapeptide. Reversed-phase chromatography then separates the main peak from related impurities. Neither technique alone establishes residue order, so sequence-level confirmation may call for tandem mass spectrometry or amino acid analysis.
No single published figure applies, because stability depends on pH, concentration, temperature and sterility. Cold storage slows hydrolysis without halting it, and microbial growth is a separate concern in non-sterile solutions. Most laboratories rely on their own analytical checks rather than a fixed expiry period.
It is a synthetic tetrapeptide. Its sequence was derived from research on peptide fractions of bovine pineal extract, and the intact AEDG sequence has not been demonstrated as an abundant free peptide in human tissue.