mass spectrometry raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-08-08. Anything still debated is marked as such rather than presented as settled.
Laboratory work has examined effects on telomerase activity in cultured cells, on melatonin rhythms in animals, and on markers of oxidative stress. Some experiments report measurable changes while others show none, and the reported findings rest largely on small studies. The absence of large independent trials means the generality of these results is unresolved rather than settled. Review articles occasionally apply the label geroprotector, a term that reflects a research hypothesis about ageing rather than an established clinical finding.
Epitalon is the common name for a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, usually abbreviated AEDG. All four residues are proteinogenic amino acids, and the free peptide has a calculated mass near 390 grams per mole. Because the chain is short and carries no modifications, it is assembled readily by solid-phase synthesis and is distributed mainly as a freeze-dried solid for laboratory work. Catalogue listings use the spellings epitalon, epithalone, and simply AEDG, and the three refer to the same sequence.
The compound is generally presented as a synthetic fragment of epithalamin, a pineal gland extract investigated in the former Soviet Union from the 1970s onward. Vladimir Khavinson and colleagues in Saint Petersburg developed short peptides modelled on such extracts, and epitalon became the most widely cited of those sequences. Most primary reports appeared in Russian-language journals or in proceedings with limited international circulation. Independent replication in laboratories outside that network remains sparse, and much repeated secondary material traces back to a small number of originating groups.
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 | Computed for the free acid of Ala-Glu-Asp-Gly |
| Molecular mass | About 390.35 g/mol | Free peptide; salt forms shift the value |
| Appearance | White to off-white solid | Typical of short peptides after freeze-drying |
| Solubility class | Freely soluble in water | Aqueous buffers are also commonly used |
| Common synonyms | Epitalon, epithalone, AEDG | AEDG is the single-letter sequence |
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.
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.
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.
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.
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.
However, CSP expressing secretions and tissues are not only the female moth pheromone gland, but also antennal branches, mandibles and salivae, cephalic capsula, eyes, proboscis, thorax and abdomen, head, epidermis, fat body, gut, wings and legs, i.e. a wide range of reproductive and non reproductive, sensory and non-sensory fluids and tissues of the insect body [28-31]. Nearly all CSPs are up regulated in most of all tissues from the insect body, particularly in the gut, epidermis and fat body, following insecticide exposure [32].
radical Also free radical. Any atom, molecule, or ion that has at least one unpaired valence electron. With few exceptions, such unpaired electrons make radicals highly chemically reactive, and therefore organic radicals are usually short-lived.
In 1983 Stuart Beal (and also independently Santiago Schnell and Claudio Mendoza in 1997) derived a closed form solution for the time course kinetics analysis of the Michaelis-Menten mechanism. The solution, known as the Schnell-Mendoza equation, has the form:
Hubert Humphrey, Rep. Findley's bill ultimately became Title XII of the Foreign Assistance Act, via an amendment to the FAA passed in 1975. Title XII created the Board for International Food and Agricultural Development (BIFAD), with seven members representing U.S. universities and agricultural technology institutions who advise USAID on Title XII implementation. The impact of all these actions of the early 1970s on the overall scale of U.S. development assistance is indicated by the change in the number of U.S. staff in field missions. In 1969, the year when Nixon took office, the number was already decreasing from its Vietnam War high of 8,717 and had reached 7,701. By 1976, near the end of the Nixon-Agnew and Ford-Rockefeller administrations, it was 2,007.
Sources: en.wikipedia.org
Significance of research: All experiments are carried out at 60 °C. Changes in the equilibrium constant (K) are used to determine what type of lipid interactions are occurring within the modeled membrane as well as observe liquid-ordered versus liquid-disorder regions. The value of the equilibrium constant determine the following: 1) if monomers are mixed ideally (K = 4.0) 2) when the monomers are mixed homogenously also referred to as a homo-association (K < 4.0) and 3) if the monomers have interchanged heterogeneously which is referred to as an hetero-association (K > 4.0) A plot of (K) is then created versus the cholesterol mol%. Each plot has similar trends in which the value of the equilibrium constant increased as the mol% increased with and without the presence of ethanol indicating a linear regression. Initially all the model membranes were organized in a liquid order phase but as the addition of cholesterol increase a liquid-disorder phase was observed. The following was determined regarding the liquid-order and liquid-disordered transitions during the addition of cholesterol in the presence of ethanol in each model membrane: 1) 0–15 mol% cholesterol a liquid-disordered phase was present 2) from 15 to 30 mol% there was a co-existence of both phases and 3) above 27 mole% of cholesterol the model membrane completed converted back to the original liquid-order phase within a two-hour time frame. The linear regression maxed out at 30 mol% of cholesterol.
David Mora, an expert at the Crisis Group analysis center, noted to AFP that due to his lack of direct succession, with his son being held in the United States, El Mencho's death created a power vacuum in the CJNG, with this power vacuum also being a major reason for the escalation in violence, stating "in the absence of a direct succession, a power vacuum is created that opens the door to violent realignments within the organization." Former DEA Chief of International Operations Mike Vigil stated to CBS News that El Mencho's death was prominent and that Mexico could seize on the moment to launch "an effective frontal assault based on intelligence," while also acknowledging that "This is a big opportunity for Mexico and the United States if they work together." El Jardinero would eventually be captured in April 2026. According to Mexican Secretary of the Navy Raymundo Pedro Morales Ángeles, El Jardinero at the time served as “the second in command of the CJNG" and had been "one of the most trusted men (of El Mencho)." However, following El Mencho's death, he also made a major attempt to seize control of the CJNG, mobilizing “personnel, weapons and resources with the aim of taking over the power of the criminal organization.”
== Molecular problem: fibrosis == When faced with pressure overload, the heart attempts to compensate with a number of structural alterations including hypertrophy of cardiomyocytes and increase of extracellular matrix (ECM) proteins. Rapid accumulation of ECM proteins causes excessive fibrosis resulting in decreased myocardial compliance and increased myocardial stiffness. The exact mechanisms involved in excessive fibrosis are not fully understood but there is evidence that supports involvement from local growth factors FGF-2, TGF-beta and platelet-derived growth factor. TGF-β1 plays an important role in cardiac remodelling through the stimulation of fibroblast proliferation, ECM deposition and myocyte hypertrophy. The increase in TGF-beta 1 expression in a pressure-overloaded heart correlates with the degree of fibrosis, suggesting TGF-beta 1 involvement in the progression from a compensated hypertrophy to failure. Through an autocrine mechanism, TGF-beta 1 acts on fibroblasts by binding TGF-beta 1 receptors 1 and 2. Upon receptor activation, the receptor-associated transcription factor Smad becomes phosphorylated and associates with Co-Smad. This newly formed Smad-Co-Smad complex enters the nucleus where it acts as a transcription factor modulating gene expression. Cardiac remodelling of the ECM is also regulated by the CNP/NPR-B pathway as demonstrated by the improved outcomes in transgenic mice with CNP over-expression subjected to myocardial infarction.
Concerns about possible adverse effects are that intravenous high-dose vitamin C leads to a supraphysiological level of vitamin C followed by oxidative degradation to dehydroascorbic acid and hence to oxalate, increasing the risk of oxalate kidney stones and oxalate nephropathy. The risk may be higher in people with renal impairment, as kidneys efficiently excrete excess vitamin C. Second, treatment with high dose vitamin C should be avoided in patients with glucose-6-phosphate dehydrogenase deficiency as it can lead to acute hemolysis. Third, treatment might interfere with the accuracy of glucometer measurement of blood glucose levels, as both vitamin C and glucose have similar molecular structure, which could lead to false high blood glucose readings. Despite all these concerns, meta-analyses of patients in intensive care for sepsis, septic shock, COVID-19 and other acute conditions reported no increase in new-onset kidney stones, acute kidney injury or requirement for renal replacement therapy for patients receiving short-term, high-dose, intravenous vitamin C treatment. This suggests that intravenous vitamin C is safe under these short-term applications.
=== Generalized anxiety disorder === SSRIs are recommended by the National Institute for Health and Care Excellence (NICE) for the treatment of generalized anxiety disorder (GAD) in adults who have not responded to initial interventions such as education, self-help strategies, or psychological therapies. SSRIs are more effective than placebo for treating GAD with similar overall acceptability, though they increase dropout due to adverse effects.
Sources: en.wikipedia.org
== History == Results of a Phase I clinical trial were reported in 2016. In December 2019, enfortumab vedotin was approved in the United States for the treatment of adult patients with locally advanced or metastatic urothelial cancer who had previously received a programmed cell death receptor-1 (PD-1) or programmed death ligand 1 (PD-L1) inhibitor and a platinum-containing chemotherapy. The approval was based on the results of a clinical trial of 125 such patients. The overall response rate, reflecting the percentage of patients who had a certain amount of tumor shrinkage, was 44%; specifically, 12% had a complete response and 32% a partial response. The median duration of response was 7.6 months. The U.S. Food and Drug Administration (FDA) granted the application for enfortumab vedotin accelerated approval, priority review designation, and breakthrough therapy designation. The FDA granted the approval of Padcev to Astellas Pharma US Inc. In July 2021, the FDA approved enfortumab vedotin for adults with locally advanced or metastatic urothelial cancer who have previously received a PD-1 or PD-L1 inhibitor and platinum-containing chemotherapy, or who are ineligible for cisplatin-containing chemotherapy and have previously received therapy.
=== Common biochemistry === All known forms of life are based on the same fundamental biochemical organization: genetic information encoded in DNA, transcribed into RNA, through the effect of protein- and RNA-enzymes, then translated into proteins by (highly similar) ribosomes, with ATP, NADPH and others as energy sources. Analysis of small sequence differences in widely shared substances such as cytochrome c further supports universal common descent. Some 23 proteins are found in all organisms, serving as enzymes carrying out core functions like DNA replication. The fact that only one such set of enzymes exists is convincing evidence of a single ancestry. 6,331 genes common to all living animals have been identified; these may have arisen from a single common ancestor that lived 650 million years ago in the Precambrian.
the equation reduces to the incompressible-flow form. The constant on the right-hand side is often called the Bernoulli constant and denoted b. For steady inviscid adiabatic flow with no additional sources or sinks of energy, b is constant along any given streamline. More generally, when b may vary along streamlines, it still proves a useful parameter, related to the "head" of the fluid (see below). When the change in Ψ can be ignored, a very useful form of this equation is:
== Early life == Hird is the son of Allan and Margaret Hird. He was born in Canberra, where his father worked in the public service and his mother was a teacher, although they had met in Melbourne. Hird has two younger sisters. After first living in the Canberra suburb of Ainslie, his family moved to Latham. When Hird was in high school, the family moved to the suburb of Reid. Hird participated in rugby league, ballet, and soccer in his youth. He played for the Ainslie Football Club in the ACTAFL, and in June 1990, at the age of 17, he was a member of the league's senior representative team in a match against the Victorian Football Association.
Sources: en.wikipedia.org
It is a four-amino-acid peptide with the sequence alanine-glutamate-aspartate-glycine. The chain is unmodified and contains only standard proteinogenic residues, which makes it straightforward to produce by solid-phase synthesis and to characterise by standard peptide methods.
Epitalon and epithalon both circulate, and the difference reflects transliteration of a name coined in Russian-language publications. Reference to the extract it derives from, epithalamin, explains the shared stem. Databases and suppliers are inconsistent, so a search for one spelling alone may miss relevant entries.
No. Epithalamin is a multi-component preparation obtained from pineal tissue, and its exact composition is not fully characterised. Epitalon is a single defined tetrapeptide described as a short synthetic counterpart of that extract, so the two are related in origin but not interchangeable in identity.
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.