The short version of HPLC purity fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-10-31. Anything still debated is marked as such rather than presented as settled.
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.
Storage recommendations center on limiting moisture, heat, and light. The dry powder is generally kept at minus 20 degrees Celsius, and some suppliers recommend minus 80 degrees for long-term archival. Once dissolved, solutions are usually aliquoted and frozen to avoid repeated freeze-thaw cycles, which can promote aggregation or degradation. Aqueous stability depends on pH and concentration, and buffered saline is often preferred over plain water for biological work. Stability data specific to epitalon remain limited, so general peptide-handling practices are applied by analogy rather than from product-specific validation.
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.
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.
| 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 |
Epitalon is a synthetic tetrapeptide whose sequence is alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. It was developed in Russia during the 1980s and 1990s by investigators associated with the St. Petersburg Institute of Bioregulation and Gerontology, who studied short peptides as regulators of gene expression and tissue function. The alternative spelling epithalon appears interchangeably in the literature, and the two names refer to the same molecule. Outside Russia it is encountered chiefly as a research chemical rather than a licensed medicine, and it holds no approval from the United States Food and Drug Administration or the European Medicines Agency.
The peptide is a synthetic analogue of epithalamin, a preparation extracted from bovine pineal glands. Investigators sought a short, chemically defined molecule that would reproduce some of the endocrine and gerontological observations attributed to the glandular extract. Proposed mechanisms centre on induction of telomerase activity, an effect reported in cultured human somatic cells in the early 2000s, together with influences on melatonin secretion and neuroendocrine regulation. Those mechanisms remain incompletely characterised, and the reported telomerase response has not been consistently reproduced by independent groups working in comparable systems.
Published work on this compound consists mainly of in vitro experiments, animal studies, and small clinical investigations, a substantial share of which appeared in Russian-language journals. Sample sizes are generally small, control conditions differ between studies, and several endpoints rely on markers whose clinical meaning is itself debated. Reviews of the longevity field treat the peptide as an early example of telomerase-directed research rather than an established intervention. Regulatory treatment varies by country: some jurisdictions place it under prescription controls, others treat it as a laboratory material, and importation may be restricted regardless of local status.
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 with the residue sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its monoisotopic mass is approximately 390.35 daltons, and it is usually supplied as a lyophilised trifluoroacetate or acetate salt. The compound was derived from a pineal gland extract called epithalamin, a heterogeneous preparation investigated in the former Soviet Union. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology described the tetrapeptide as a constituent fragment of that extract. Commercial material is offered as a laboratory reagent rather than as a finished pharmaceutical product.
Literature searches for this compound must account for several spelling variants. Indexing databases contain epitalon, epithalon, epithalone, and AEDG, and relevant records are scattered across Russian-language and English-language journals that do not consistently cross-cite. Early publications describe the parent extract as a mixture of many peptides, whereas later work addresses the single synthetic tetrapeptide. That shift in nomenclature complicates comparison between studies, because extract data and tetrapeptide data are sometimes cited interchangeably. A search strategy omitting the alternate spellings will return an incomplete set of references.
Reported biological findings come mainly from cell culture and rodent experiments. Those studies describe changes in telomerase catalytic subunit expression, melatonin rhythm amplitude, and antioxidant enzyme activity after peptide exposure. Human data are sparse and consist of small trials with limited blinding and inconsistent endpoints. The proposed mechanisms remain hypotheses rather than established facts, and there is no consensus on whether effects observed in animals carry over to people. Independent replication outside the original research groups is limited, which is a recognised gap in the published literature.
The magnitude of sensory impairment may vary in people of differing weights. The NIAAA defines the term "binge drinking" as a pattern of drinking that brings a person's blood alcohol concentration (BAC) to 0.08 grams percent or above.
== Veterinary use == Sufentanil is used both as an analgesic and as part of an anaesthetic protocol. In cats the half-life of sufentanil is longer than that of fentanyl and alfentanil. In dogs sufentanil produces a better anaesthetic recovery with similar analgesic and respiratory depression than fentanyl. One report suggest that for post-operative pain bupivacaine and sufentanil provides greater analgesia than fentanyl and bupivacaine in dogs. There is little information on the use of sufentanil in large animals. Due to the greater risk of cardiovascular and respiratory depression sufentanil is rarely used in practice.
=== CTLA-4 blockade === The first checkpoint antibody approved by the FDA was ipilimumab, approved in 2011 to treat melanoma. It blocks the immune checkpoint molecule CTLA-4. As of 2012, clinical trials have also shown some benefits of anti-CTLA-4 therapy on lung cancer or pancreatic cancer, specifically in combination with other drugs. In on-going trials the combination of CTLA-4 blockade with PD-1 or PD-L1 inhibitors is tested on different types of cancer. However, as of 2015 it is known that patients treated with checkpoint blockade (specifically CTLA-4 blocking antibodies), or a combination of check-point blocking antibodies, are at high risk of having immune-related adverse events such as dermatologic, gastrointestinal, endocrine, or hepatic autoimmune reactions. These are most likely due to the breadth of the induced T-cell activation when anti-CTLA-4 antibodies are administered by injection in the bloodstream. A 2024 cohort study of ICI use during pregnancy showed no overreporting of specific adverse effects on pregnancy, fetal, and/or newborn outcomes, interestingly. Using a mouse model of bladder cancer, researchers have found that a local injection of a low dose anti-CTLA-4 in the tumour area had the same tumour inhibiting capacity as when the antibody was delivered in the blood. At the same time the levels of circulating antibodies were lower, suggesting that local administration of the anti-CTLA-4 therapy might result in fewer adverse events.
Sources: en.wikipedia.org
==== HCG Pubergen, Pregnyl warnings ==== In the case of female patients who want to be treated with HCG Pubergen, Pregnyl: a) Since infertile female patients who undergo medically assisted reproduction (especially those who need in vitro fertilization), are known to often be suffering from tubal abnormalities, after a treatment with this drug they might experience many more ectopic pregnancies. This is why early ultrasound confirmation at the beginning of a pregnancy (to see whether the pregnancy is intrauterine or not) is crucial. Pregnancies that have occurred after a treatment with this drug have a higher risk of multiple pregnancy. Female patients who have thrombosis, severe obesity, or thrombophilia should not be prescribed this medicine as they have a higher risk of arterial or venous thromboembolic events after or during a treatment with HCG Pubergen, Pregnyl. b)Female patients who have been treated with this medicine are usually more prone to pregnancy losses. In the case of male patients: A prolonged treatment with HCG Pubergen, Pregnyl is known to regularly lead to increased production of androgen. Therefore: Patients who have overt or latent cardiac failure, hypertension, renal dysfunction, migraines, or epilepsy might not be allowed to start using this medicine or may require a lower dose of HCG Pubergen, Pregnyl. This drug should be used with extreme caution in the treatment of prepubescent teenagers in order to reduce the risk of precocious sexual development or premature epiphyseal closure.
Patients being treated for osteoporosis or non-malignant bone disease with oral bisphosphonates/quarterly or yearly infusions of intravenous bisphosphonates for >5 years Patients being treated for osteoporosis or non-malignant bone disease with bisphosphonates/denosumab for any length of time as well as being treated with systemic glucocorticoids Patients being treated with anti-resorptive/anti-angiogenic drugs/both as part of cancer management Previous MRONJ diagnosis "N.B. Patients who have taken bisphosphonate drugs at any time in the past and those who have taken denosumab in the last nine months are allocated to a risk group as if they are still taking the drug."
Protein synthesis within chloroplasts relies on two RNA polymerases. One is coded by the chloroplast DNA, the other is of nuclear origin. The two RNA polymerases may recognize and bind to different kinds of promoters within the chloroplast genome. The ribosomes in chloroplasts are similar to bacterial ribosomes.
Sources: en.wikipedia.org
== Estimation == In clinical practice, however, creatinine clearance or estimates of creatinine clearance based on the serum creatinine level are used to measure GFR. Creatinine is produced naturally by the body (creatinine is a breakdown product of creatine phosphate, which is found in muscle). It is freely filtered by the glomerulus, but also actively secreted by the peritubular capillaries in very small amounts such that creatinine clearance overestimates actual GFR by 10–20%. This margin of error is acceptable, considering the ease with which creatinine clearance is measured. Unlike precise GFR measurements involving constant infusions of inulin, creatinine is already at a steady-state concentration in the blood, and so measuring creatinine clearance is much less cumbersome. However, creatinine estimates of GFR have their limitations. All of the estimating equations depend on a prediction of the 24-hour creatinine excretion rate, which is a function of muscle mass which is quite variable. The Cockcroft-Gault and CKD-EPI 2021 equations (see below) do not correct for race. With a higher muscle mass, serum creatinine will be higher for any given rate of clearance. A common mistake made when just looking at serum creatinine is the failure to account for muscle mass. Hence, an older woman with a serum creatinine of 1.4 mg/dL may actually have a moderately severe chronic kidney disease, whereas a young muscular male can have a normal level of renal function at this serum creatinine level.
Collar: worn by the president of the Republic and may be granted to other Heads of State. Grand Cordon: awarded for exceptional services to the nation. Regarding this class, the badge of the order is worn from a sash and the star of the order worn on the left chest. Although the five class structure of the original 1915 order was mentioned when the order was restructured in 1953, the four more junior grades (i.e. Grand Officer, Commander, Officer and Knight) are no longer awarded.
=== Cited texts === Borror DJ, Triplehorn CA, Delong DM (1989). Introduction to the Study of Insects (6th ed.). Saunders College Publishing. ISBN 978-0-03-025397-3. Hölldobler B, Wilson EO (1990). The Ants. Harvard University Press. ISBN 978-0-674-04075-5.
=== Sightings === The investigation into the child's disappearance was slow to commence and soon slowed down further due to the lack of credible leads. Nevertheless, the case had sparked public interest to a degree that sightings of Mendonça were numerous over the years since his disappearance. A prostitute, Alcina Dias, confirmed that Afonso had taken Mendonça to see her on the day he disappeared. Dias allegedly drove up to see her in his car and asked her if she was working. When she assented, he offered to pay her to have sex with Mendonça. Alcina Dias said that Mendonça was extremely nervous and crying by the time he exited the vehicle, reportedly saying that Afonso had forced him to meet her. Alcina Dias added that she tried to calm the boy down and asked him if his mother knew he was there, to which the boy replied no. Mendonça then allegedly drove off in Afonso's vehicle. Alcina Dias allegedly tried to give her deposition to the authorities, but could never identify Dias by name. In 2011, she finally identified him in a court of law. In April 1998, the political commentator Nuno Rogeiro traveled to Disneyland Paris with his family. During the trip, the Rogeiro family snapped several photographs whilst on a ride; one of these photos depicts a boy sitting behind the family who reportedly looks remarkably like Mendonça. Sitting next to the boy was a man in his 40s wearing a red jacket. The Portuguese police did confiscate the photographs for further analysis, but no further progress was made regarding this sighting.
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.
Vladimir Khavinson and colleagues at research institutes in Saint Petersburg developed and studied the peptide. Their program examined short peptides as regulators of aging and neuroendocrine function. Epitalon was one of several compounds produced by that group.