The short version of tetrapeptide fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-07-09. Anything still debated is marked as such rather than presented as settled.
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.
Laboratory-grade epitalon is typically supplied as a lyophilized powder. Purity is commonly assessed with reverse-phase high-performance liquid chromatography, often paired with mass spectrometry to confirm molecular identity. Amino acid analysis and peptide mapping can provide additional confirmation of sequence. Certificates of analysis for research materials frequently report purity above 95 percent, although the methods behind such figures vary between suppliers. The absence of a pharmacopeial monograph means that no single standardized assay defines the compound, so reported results depend on the analytical protocol chosen.
Verification of a sample usually begins with reversed-phase high-performance liquid chromatography, which resolves the peptide from truncated sequences and other impurities and expresses purity as a percentage of total peak area. Mass spectrometry by electrospray ionisation or matrix-assisted laser desorption supplies an independent check, because the measured mass can be compared against the theoretical value for AEDG. Amino acid analysis or tandem mass spectrometry sequencing can confirm residue order. Each of these methods answers a different question: a purity figure does not establish identity, and an identity match does not establish how much of the material is intact peptide.
The molecule is a short, linear, hydrophilic peptide that dissolves readily in water or aqueous buffer. Its principal chemical liabilities are hydrolytic rather than oxidative, since it contains no cysteine, methionine, or tryptophan residues. The aspartate–glycine step is a recognised site for aspartimide formation under mildly acidic or basic conditions, generating isoaspartate and succinimide-related products over time. Desiccated lyophilised powder held at −20 °C is comparatively stable, whereas dilute solutions degrade faster and are best frozen as single-use aliquots rather than thawed repeatedly.
No pharmacopoeial monograph exists for this peptide, so quality rests on the supplier's internal specifications and on whatever independent testing a purchaser arranges. Certificates of analysis differ widely in which tests they report and in the limits applied. The counter-ion introduced during purification, commonly acetate or trifluoroacetate, changes the net peptide content of a given mass of powder, so two samples of equal weight may not contain equal amounts of the active sequence. Third-party laboratories can verify purity, identity, residual solvents, and counter-ion content for a fee, which makes documentation more informative than labelling.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Free acid form of the tetrapeptide |
| Molecular mass | About 390.35 Da | Calculated monoisotopic value |
| Appearance | White to off-white powder | Typical lyophilized presentation |
| Solubility | Soluble in water | Also dissolves in buffered saline |
| Storage temperature | Minus 20 degrees Celsius | Dry, dark conditions; avoid repeated thawing |
Chemically, the molecule consists of four amino acid residues joined by three peptide bonds, with a free N-terminal amino group and a free C-terminal carboxyl group. Its molecular formula is C14H22N4O9, and its monoisotopic mass is approximately 390 daltons. The acidic glutamate and aspartate side chains give the peptide a net negative charge near neutral pH, a property that shapes its chromatographic behaviour and solubility profile. No disulfide bridges or other post-translational modifications are present, so the primary sequence alone defines the structure.
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.
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.
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.
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.
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.
== Potential applications == Due to the ability of laccase to catalyze oxidation reactions of a range of substrates, the use of laccase as a biocatalyst in different industrial applications have been investigated. Laccases have been applied in the production of wines. Laccase is produced by a number of fungal species that can infect grapes, most notably Botrytis cinerea Pers. (1794). Laccase is active at wine pH and its activity is not readily suppressed by sulfur dioxide. It has been noted to cause oxidative browning in white wines and loss of colour in red wines. It can also degrade a number of key phenolic compounds critical to wine quality. Aside from wine, laccases are of interest in the food industry, including food packaging. The ability of laccases to modify complex organic molecules has attracted attention in the area of organic synthesis. Laccases have been also been studied as catalysts in bioremediation to degrade emerging pollutants and pharmaceuticals.
The United States based its Cold War coalition primarily on the Baghdad Pact of 1955 which formed Central Treaty Organization (CENTO), that included Iran, Iraq, Pakistan, Turkey and the United Kingdom.
== Overview == The metabolic processes of all organisms can only take place in very specific physical and chemical environments. The conditions vary with each organism, and also with whether the chemical processes take place inside the cell or in the interstitial fluid bathing the cells. The best-known homeostatic mechanisms in humans and other mammals are regulators that keep the composition of the extracellular fluid (or the "internal environment") constant, especially with regard to the temperature, pH, osmolality, and the concentrations of sodium, potassium, glucose, carbon dioxide, and oxygen. However, a great many other homeostatic mechanisms, encompassing many aspects of human physiology, control other entities in the body. Where the levels of variables are higher or lower than those needed, they are often prefixed with hyper- and hypo-, respectively such as hyperthermia and hypothermia or hypertension and hypotension.
Sources: en.wikipedia.org
Tiredness (fatigue) Dizziness Headaches Cold hands and feet Pale skin Dark urine Jaundice Chest pain Pain in the back or legs Vomiting or diarrhea Heart problems such as an irregular heartbeat (arrhythmia), a heart murmur, an enlarged heart, or heart failure. These may occur because the heart has to work harder to make sure the body gets enough healthy red blood cells. Many people with CAD also experience pain and bluish coloring of the hands and feet (acrocyanosis) or Raynaud's disease. These symptoms result from slow or poor circulation and can range from mild to disabling. Other signs and symptoms of CAD may include enlargement of the spleen (splenomegaly) and mottled discoloration of the skin (livedo reticularis). In people with secondary CAD (associated with another underlying condition), there may be additional signs and symptoms depending on the condition present. For example: Mycoplasma pneumoniae infection (the most common cause of secondary CAD) may cause respiratory symptoms. Various infections or cancers may cause enlarged or swollen lymph nodes.
=== Women with cancer === In women with cancer, radiation therapy and chemotherapy can damage the ovarian reserve. In such cases, a pre-treatment AMH is useful in predicting the long-term post-chemotherapy loss of ovarian function, which may indicate fertility preservation strategies such as oocyte cryopreservation. A post-treatment AMH is associated with decreased fertility. Granulosa cell tumors of the ovary secrete AMH, and AMH testing has a sensitivity ranging between 76 and 93% in diagnosing such tumors. AMH is also useful in diagnosing recurrence of granulosa cell tumors.
Local anesthesia of oral and pharyngeal mucous membranes (sore throat, cold sores, mouth ulcers, toothache, sore gums, denture irritation) Otic pain (earache) Surgical or procedural local anesthesia Relief of skin pain caused by sunburn, ingrown toenails, hemorrhoids, Examples of combination medications of benzocaine include:
Sources: en.wikipedia.org
== Diagnosis == Acanthosis nigricans is typically diagnosed clinically based on its characteristic velvety hyperpigmentation and distribution. A skin biopsy is rarely needed but, when performed, shows hyperkeratosis, papillomatosis and mild basal hyperpigmentation. Evaluation aims to identify associated conditions. Investigations may include:
=== Dendritogenesis === Local interaction of BDNF with the TrkB receptor on a single dendritic segment is able to stimulate an increase in PSD-95 trafficking to other separate dendrites as well as to the synapses of locally stimulated neurons. PSD-95 localizes the actin-remodeling GTPases, Rac and Rho, to synapses through the binding of its PDZ domain to kalirin, increasing the number and size of spines. Thus, BDNF-induced trafficking of PSD-95 to dendrites stimulates actin remodeling and causes dendritic growth in response to BDNF.
== Function == In mice, the agouti gene encodes a paracrine signalling molecule that causes hair follicle melanocytes to synthesize the yellow pigment pheomelanin instead of the black or brown pigment eumelanin. Pleiotropic effects of constitutive expression of the mouse gene include adult-onset obesity, increased tumor susceptibility, and premature infertility. This gene is highly similar to the mouse gene and encodes a secreted protein that may (1) affect the quality of hair pigmentation, (2) act as an inverse agonist of alpha-melanocyte-stimulating hormone, (3) play a role in neuroendocrine aspects of melanocortin action, and (4) have a functional role in regulating lipid metabolism in adipocytes. In mice, the wild type agouti allele (A) presents a grey phenotype, however, many allele variants have been identified through genetic analyses, which result in a wide range of phenotypes distinct from the typical grey coat. The most widely studied allele variants are the lethal yellow mutation (Ay) and the viable yellow mutation (Avy) which are caused by ectopic expression of agouti. These mutations are also associated with yellow obese syndrome which is characterized by early onset obesity, hyperinsulinemia and tumorigenesis. The murine agouti gene locus is found on chromosome 2 and encodes a 131 amino acid protein. This protein signals the distribution of melanin pigments in epithelial melanocytes located at the base of hair follicles with expression being more sensitive on ventral hair than on dorsal hair.
Biological research in cold seeps and hydrothermal vents has been mostly focused on the microbiology and the prominent macro-invertebrates thriving on chemosynthetic microorganisms. Much less research has been done on the smaller benthic fraction at the size of the meiofauna (<1 mm). A community composition's orderly shift from one set of species to another is called ecological succession. The first type of organism to take advantage of this deep-sea energy source is bacteria. Aggregating into bacterial mats at cold seeps, these bacteria metabolize methane and hydrogen sulfide (another gas that emerges from seeps) for energy. This process of obtaining energy from chemicals is known as chemosynthesis.
Sources: en.wikipedia.org
Epitalon is a synthetic tetrapeptide built from four amino acids: alanine, glutamate, aspartate, and glycine. It is not extracted from a natural source but made in the laboratory by chemical synthesis. Its short length makes it relatively straightforward to produce at high purity.
No naturally occurring free form of the peptide has been described. The four-amino-acid sequence can appear as a fragment within larger proteins, but that is not the same as the intact compound being present as a circulating molecule. Materials used in research are synthetic.
Purity is usually checked by reverse-phase high-performance liquid chromatography, which separates the target peptide from related impurities. Mass spectrometry is commonly used alongside it to confirm molecular mass. Some suppliers also provide amino acid analysis for additional sequence confirmation.
Mass spectrometry provides the identity check, because the observed mass is compared with the theoretical mass of the AEDG sequence. Chromatography separates and quantifies impurities but does not by itself prove which peptide is present. The two techniques are normally used together.