reversed-phase HPLC is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-04-29. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Electrospray or MALDI mass spectrometry | Observed mass compared with theoretical 390.35 Da |
| Purity specification | 95 percent or greater by RP-HPLC | Common convention for research-grade peptide |
| Counter-ion | Acetate or trifluoroacetate | Affects net peptide content of a weighed sample |
| Solution storage | −80 °C as single-use aliquots | Repeated freeze–thaw cycles accelerate loss |
| Main degradation route | Aspartimide formation at Asp-Gly | Produces isoaspartate and related species |
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.
Epitalon emerged from research conducted in Saint Petersburg by Vladimir Khavinson and colleagues, who studied short peptides as potential regulators of aging. The work built on epithalamin, a pineal gland extract reported to influence neuroendocrine function. Epitalon was designed as a synthetic counterpart with a defined sequence, allowing reproducible experiments that extracts could not support. Early publications described effects on melatonin rhythms and lifespan in animal models. These findings circulated mainly in Russian-language journals during the 1990s, which limited their visibility among English-speaking researchers.
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.
Regulatory treatment differs by country. No formulation of epitalon holds a marketing authorisation as a medicine in the United States or the European Union, where material sold for laboratory use is handled as a research chemical and is not intended for human consumption. In Russia, several short peptide preparations from the same institute's peptide series are registered medicinal products, and epitalon appears in that national context. Elsewhere it is frequently offered as a cosmetic ingredient, a category with lighter requirements. Advertising claims about longevity or disease prevention are restricted in most jurisdictions, which limits how sellers describe the compound.
Freeze-dried epitalon is normally kept at minus twenty degrees Celsius in a sealed, desiccated container, protected from light. Short excursions at ambient temperature during shipping are generally tolerated, but repeated warming and cooling cycles encourage moisture uptake, which shortens shelf life. Once dissolved, the peptide is far less stable than the solid: aqueous solutions are subject to hydrolysis and to deamidation at the aspartate and glutamate residues. Working solutions are therefore held refrigerated and used within days, and repeated freezing and thawing of the same vial is best avoided.
=== Hyperinsulinemic hypoglycemia === Some mutations have been found to enhance insulin secretion. Heterozygosity for gain of function mutations reduces the threshold glucose that triggers insulin release. This creates hypoglycemia of varying patterns, including transient or persistent congenital hyperinsulinism, or fasting or reactive hypoglycemia appearing at an older age. The most recent overview of GCK mutation that were observed in patients claimed 17 GCK mutations to cause hyperinsulinemic hypoglycemia. Homozygosity for gain of function mutations has not been found.
Early histological features expected to be seen on examination of gynecomastic tissue attained by fine-needle aspiration biopsy include the following: proliferation and lengthening of the ducts; an increase in connective tissue; an increase in inflammation; and swelling surrounding the ducts; and an increase in fibroblasts in the connective tissue. Chronic gynecomastia may show different histological features such as increased connective tissue fibrosis, an increase in the number of ducts, less inflammation than in the acute stage of gynecomastia, increased subareolar fat, and hyalinization of the stroma. When surgery is performed, the gland is routinely sent to the lab to confirm the presence of gynecomastia and to check for tumors under a microscope. The utility of pathologic examination of breast tissue removed from male adolescent gynecomastia patients has recently been questioned due to the rarity of breast cancer in this population.
Endocrine glands secrete substances that circulate in the blood. The glands secrete their products through basal lamina into the bloodstream. Basal lamina typically can be seen as a layer around the glands to which more than a million tiny blood vessels are attached. These glands often secrete hormones which play an important role in maintaining homeostasis. The pineal gland, thymus, pituitary gland, thyroid gland, and the two adrenal glands are all endocrine glands.
Sources: en.wikipedia.org
== Prognosis == As of 2012, the five-year survival rate for systemic scleroderma was about 85%, whereas the 10-year survival rate was just under 70%. This varies according to the subtype; while localized scleroderma rarely results in death, the systemic form can, and the diffuse systemic form carries a worse prognosis than the limited form. The major scleroderma-related causes of death are: pulmonary hypertension, pulmonary fibrosis, and scleroderma renal crisis. People with scleroderma are also at a heightened risk for developing osteoporosis and for contracting cancer (especially liver, lung, haematologic, and bladder cancers). Scleroderma is also associated with an increased risk of cardiovascular disease. According to a study of an Australian cohort, between 1985 and 2015, the average life expectancy of a person with scleroderma increased from 66 years to 74 years (the average Australian life expectancy increased from 76 to 82 years in the same period).
=== Differential diagnosis === There are many causes of chest pain, which can originate from the heart, lungs, gastrointestinal tract, aorta, and other muscles, bones and nerves surrounding the chest. In addition to myocardial infarction, other causes include angina, insufficient blood supply (ischemia) to the heart muscles without evidence of cell death, gastroesophageal reflux disease; pulmonary embolism, tumors of the lungs, pneumonia, rib fracture, costochondritis, heart failure and other musculoskeletal injuries. Rarer severe differential diagnoses include aortic dissection, esophageal rupture, tension pneumothorax, and pericardial effusion causing cardiac tamponade. The chest pain in an MI may mimic heartburn. Causes of sudden-onset breathlessness generally involve the lungs or heart – including pulmonary edema, pneumonia, allergic reactions and asthma, and pulmonary embolus, acute respiratory distress syndrome and metabolic acidosis. There are many different causes of fatigue, and myocardial infarction is not a common cause.
== Function == Several lines of evidence suggest that PD-1 and its ligands negatively regulate immune responses. PD-1 knockout mice have been shown to develop lupus-like glomerulonephritis and dilated cardiomyopathy on the C57BL/6 and BALB/c backgrounds, respectively. In vitro, treatment of anti-CD3 stimulated T cells with PD-L1-Ig results in reduced T cell proliferation and IFN-γ secretion. IFN-γ is a key pro-inflammatory cytokine that promotes T cell inflammatory activity. Reduced T cell proliferation was also correlated with attenuated IL-2 secretion and together, these data suggest that PD-1 negatively regulates T cell responses. Experiments using PD-L1 transfected DCs and PD-1 expressing transgenic (Tg) CD4+ and CD8+ T cells suggest that CD8+ T cells are more susceptible to inhibition by PD-L1, although this could be dependent on the strength of TCR signaling. Consistent with a role in negatively regulating CD8+ T cell responses, using an LCMV viral vector model of chronic infection, Rafi Ahmed's group showed that the PD-1-PD-L1 interaction inhibits activation, expansion and acquisition of effector functions of virus specific CD8+ T cells, which can be reversed by blocking the PD-1-PD-L1 interaction. Expression of PD-L1 on tumor cells inhibits anti-tumor activity through engagement of PD-1 on effector T cells. Expression of PD-L1 on tumors is correlated with reduced survival in esophageal, pancreatic and other types of cancers, highlighting this pathway as a target for immunotherapy.
==== Charge rate ==== The company's planned 2025 batteries were projected to have a peak charging rate of 350kW and a service life of 1000 fast-charging cycles. StoreDot battery cells require liquid cooling within each cell during fast charging. StoreDot announced their 2025 batteries would charge at a rate that adds 100 miles in 5 minutes for a vehicle that uses 14kWh per 100 kilometers, which corresponds to a charging rate of 270kW. StoreDot had been developing faster-charging cells that charge a 75kWh battery 70% in 10 minutes (from 10% to 80%) which corresponds to a charging rate of 315kW, which it aimed to deliver in 2026. StoreDot stated in 2026 it needs two more years of development in order to commercialize its product.
Sources: en.wikipedia.org
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.
Yes. Trifluoroacetate and acetate ions remain associated with the peptide after purification, so a weighed quantity of powder contains less peptide than the nominal mass suggests. Certificates that report net peptide content rather than raw weight are more directly comparable between suppliers.
Dilute aqueous solutions are less stable than the dry powder and are usually aliquoted and frozen to avoid repeated freeze–thaw cycles. Lyophilised material is best stored desiccated at −20 °C, protected from light. Working solutions are typically prepared fresh from a frozen aliquot.
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.