A practical reference on Tetrapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-12-28. Anything still debated is marked as such rather than presented as settled.
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 tetrapeptide whose sequence is alanine-glutamate-aspartate-glycine, written in single-letter code as AEDG. The four residues are joined by three peptide bonds, giving a linear backbone with no branching and no disulfide bridges. Its calculated molecular mass for the free form is approximately 390.3 daltons, a figure that rises when the compound is supplied as an acetate or trifluoroacetate salt. Because the chain is short, the molecule is defined entirely by its residue order rather than by any folded three-dimensional structure.
The compound is described in the literature as a derivative of epithalamin, a preparation obtained from bovine pineal tissue. Work on this peptide family was carried out mainly by a research group in Saint Petersburg beginning in the 1980s, and the substance was later registered for clinical use in Russia under the name Epitalon. Outside that region it is generally treated as a research chemical rather than an approved medicine. Statements about its biological activity rest on a relatively small number of studies, and independent replication remains limited.
In its supplied form epitalon is a white to off-white powder, usually lyophilized and often hygroscopic. It dissolves readily in water and in aqueous buffers, and it is commonly handled as the acetate or trifluoroacetate salt to improve stability during purification and drying. The amide backbone is labile in aqueous media, so solutions are less durable than the dry solid. Handling notes in the chemical literature therefore emphasize keeping the powder dry, cool and shielded from light until it is dissolved.
| 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 |
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.
Identity and purity of epitalon samples are normally established by reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, combined with mass spectrometry. The mass spectrum confirms the expected molecular ion and can reveal truncated or oxidised by-products. Amino acid analysis after acid hydrolysis verifies that the four residues are present in the expected ratio. Certificates typically report a purity figure taken from chromatographic peak area, expressed as a percentage of total integrated signal.
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.
== Alternative Medical Causes of Altered Turgor == Altered skin turgor can be caused by chronic medical conditions completely unrelated to an individual's immediate hydration status. Systemic sclerosis, or scleroderma, is an autoimmune disorder that triggers excessive collage production, resulting in abnormally tight, hard, and shiny skin that exhibits high turgor and cannot be pinched at all. On the other hand, genetic connective tissue disorders can drastically lower baseline skin tension, making the skin hyper-elastic. Additionally, localized fluid retention or severe edema stretches the dermis tightly, masking underlying systemic dehydration by artificially inflating skin turgor measurements.
==== Adherence ==== Poor compliance with medications and follow-up visits are a major reason for treatment failure and disease progression in glaucoma patients. Poor adherence could lead to increased complication rates, thus increasing the need for non-pharmacological interventions, including surgery. Patient education and communication must be ongoing to sustain successful treatment plans for this lifelong disease with no early symptoms.
== Signs and symptoms == NL/NLD most frequently appears on the patient's shins, often on both legs, although it may also occur on forearms, hands, trunk, and, rarely, nipple, penis, and surgical sites. The lesions are often asymptomatic, but may become tender and ulcerate when injured. The first symptom of NL is often a "bruised" appearance (erythema) that is not necessarily associated with a known injury. The extent to which NL is inherited is unknown. NLD appears as a hardened, raised area of the skin. The center of the affected area usually has a yellowish tint, while the area surrounding it is a dark pink. The affected area can spread or turn into an open sore. When this happens, the patient is at greater risk of developing ulcers. If an injury to the skin occurs on the affected area, it may not heal properly, or it will leave a dark scar.
Sources: en.wikipedia.org
Hypersensitivity to methocarbamol or any of the injection components. For the injectable form, suspected kidney failure or renal pathology, due to large content of polyethylene glycol 300 that can increase pre-existing acidosis and urea retention.
=== Logic === Formal logic is used for reasoning and knowledge representation. Formal logic comes in two main forms: propositional logic (which operates on statements that are true or false and uses logical connectives such as "and", "or", "not" and "implies") and predicate logic (which also operates on objects, predicates and relations and uses quantifiers such as "Every X is a Y" and "There are some Xs that are Ys"). Deductive reasoning in logic is the process of proving a new statement (conclusion) from other statements that are given and assumed to be true (the premises). Proofs can be structured as proof trees, in which nodes are labelled by sentences, and children nodes are connected to parent nodes by inference rules. Given a problem and a set of premises, problem-solving reduces to searching for a proof tree whose root node is labelled by a solution of the problem and whose leaf nodes are labelled by premises or axioms. In the case of Horn clauses, problem-solving search can be performed by reasoning forwards from the premises or backwards from the problem. In the more general case of the clausal form of first-order logic, resolution is a single, axiom-free rule of inference, in which a problem is solved by proving a contradiction from premises that include the negation of the problem to be solved. Inference in both Horn clause logic and first-order logic is undecidable, and therefore intractable. However, backward reasoning with Horn clauses, which underpins computation in the logic programming language Prolog, is Turing complete.
Göring acknowledged making the threat to the British ambassador to Germany, Nevile Henderson, but said that the threat came as a warning because the Czech government, after already agreeing to German occupation, could not guarantee that the Czech army would not fire on the advancing Germans. Göring, however, does not mention that Hácha had a heart attack because of his threat. French Ambassador Robert Coulondre reported that according to an unnamed, considered a reliable source by Coulondre, by half past four, Hácha was "in a state of total collapse, and kept going only by means of injections."
== Education and academic career == Ben-Tal studied biology, chemistry, and physics at the Hebrew University of Jerusalem, receiving his bachelor's degree in 1988. He subsequently earned a D.Sc. in chemistry from the Technion – Israel Institute of Technology in 1993, under the supervision of Professor Nimrod Moiseyev. He completed postdoctoral training with Professor Barry Honig in biophysical chemistry and computational biophysics at Columbia University in New York. In 1997, Ben-Tal joined the Department of Biochemistry and Molecular Biology at Tel Aviv University. He became a full professor in 2007. He is a member of the university's School of Neurobiology, Biochemistry and Biophysics and also serves as head of the Bioinformatics Master program within the Faculty of Life Sciences. In 2018, Ben-Tal was awarded the Abraham E. Kazan Chair of Structural Biology at Tel Aviv University.
Sources: en.wikipedia.org
Grill E, Loffler S, Winnacker E-L, Zenk MH (1989). "Phytochelatins, the heavy-metal-binding peptides of plants, are synthesized from glutathione by a specific gamma-glutamylcysteine dipeptidyl transpeptidase (phytochelatin synthase)". Proc. Natl. Acad. Sci. USA. 86 (18): 6838–6842. Bibcode:1989PNAS...86.6838G. doi:10.1073/pnas.86.18.6838. PMC 297945. PMID 16594069.
The war on cartels, also known as Operation Southern Spear, is a United States military and surveillance campaign launched in 2025 by the administration of US president Donald Trump with the declared aims of "detecting, disrupting, and degrading transnational criminal and illicit maritime networks". Some analysts say the operation is a hybridization of the war on terror and the war on drugs. Others have said that removal of Nicolás Maduro from power in Venezuela was an objective of the operation. In mid-August 2025, the US began deploying military forces to the Caribbean Sea, amid heightened tensions between the US and Venezuela during the crisis in Venezuela and as the Trump administration sought to slow the flow of illicit drugs. In September, the U.S. military began conducting airstrikes on vessels the Trump administration alleged were controlled by narco-terrorists. By late November, with the Cartel of the Suns designated by the US as a Foreign Terrorist Organization and a Specially Designated Global Terrorist organization, a new phase of operations began. In December, the Trump administration declared the Maduro government a Foreign Terrorist Organization, and began boarding and seizing sanctioned crude tankers. In late December, the US made its first strike on a land target within Venezuela. On 3 January 2026, the US bombed targets in Caracas and other locations, and captured Maduro and flew him out of the country.
=== Further processing === The N-terminal fMet is removed from majority of proteins, both host and recombinant, by a sequence of two enzymatic reactions. First, peptide deformylase (PDF) deformylates it, converting the residue back to a normal methionine. Then methionine aminopeptidase (MetAP) removes the residue from the chain. MetAP only acts on proteins with second-position residues that are less bulky than valine. The N-terminal fMet, if not removed by PDF, seems to act as a degron, a signal for protein degradation.
=== INCB Yellow List === This document contains the current list of narcotic drugs under international control and additional information to assist governments in filling in the International Narcotics Control Board questionnaires related to narcotic drugs, namely, form A, form B and form C. In medicine, a chemical agent that induces stupor, coma, or insensibility to pain (also called narcotic analgesic). In the context of international drug control, "narcotic drug" means any drug defined as such under the 1961 Convention.
== History == Efficacy was evaluated in CADENZA (NCT03386513), a multi-center, open-label, single-arm clinical trial that included adult participants with treatment-naïve blastic plasmacytoid dendritic cell neoplasm (N=33) or relapsed or refractory blastic plasmacytoid dendritic cell neoplasm (N=51), without evidence of active central nervous system disease. Efficacy was based on the rate of complete remission or clinical complete remission. The trial included 116 adult participants with CD123-positive blood or bone marrow cancers, of whom 84 participants had blastic plasmacytoid dendritic cell neoplasm. There were 33 participants who had blastic plasmacytoid dendritic cell neoplasm that was never treated before, and 51 participants had blastic plasmacytoid dendritic cell neoplasm that either came back after previous treatment or did not get better with other treatment(s). The trial occurred at 18 locations in four countries: the United States, Italy, Spain, and France. The study included 73 participants in the United States. The benefits and side effects of pivekimab sunirine were evaluated in one open-label trial in adult participants with CD123-positive blood or bone marrow cancers. The efficacy of pivekimab sunirine was evaluated in 84 participants with blastic plasmacytoid dendritic cell neoplasm who received pivekimab sunirine intravenously (through a vein) once every three weeks until the disease worsened or participants experienced unacceptable side effects.
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.
The peptide contains four residues in the order alanine, glutamate, aspartate and glycine, abbreviated AEDG. The chain is linear and held together by three peptide bonds. Its calculated mass for the uncharged free form is about 390.3 daltons.