If you have been reading about reversed-phase HPLC and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2025-09-27. Numbers and descriptions here follow the published literature rather than marketing material.
Identity and purity are checked by reversed-phase high-performance liquid chromatography, usually with ultraviolet detection near 214 nanometres, where the peptide bond absorbs. Mass spectrometry confirms the expected mass and reveals whether truncation products or adducts are present. Acid hydrolysis followed by amino acid analysis gives the residue ratio, which should approximate one alanine, one glutamate, one aspartate and one glycine. Counter-ions such as acetate or trifluoroacetate remain in the dried product and lower net peptide content, so a stated purity figure on a label does not by itself describe how much peptide a vial holds.
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.
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.
Discussions in the literature often conflate three distinct entities: the pineal extract epithalamin, the isolated tetrapeptide AEDG, and commercial preparations sold under similar names. Reviews citing older Russian-language studies sometimes omit detail on purity, route of administration and control groups, which makes cross-study comparison difficult. Researchers working with the compound generally note the need for independent replication, standardized enzyme assays, and clearer reporting of peptide identity. These caveats are relevant when weighing claims that appear in secondary sources rather than in primary reports.
| Property | Value | Notes |
|---|---|---|
| Storage temperature, solid | Approximately -20 C | Sealed, desiccated, protected from light |
| Typical identity method | Electrospray mass spectrometry | Protonated ion expected near 391 |
| Typical purity method | Reversed-phase HPLC | Ultraviolet detection near 214 nm |
| Common synonyms | Epithalon, epithalone, AEDG | Spelling variants appear in supplier catalogues |
| Solution stability | Days at 2-8 C | Hydrolysis and deamidation limit shelf life |
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.
Several names circulate for the same molecule, including epitalon, epithalone, epithalamin tetrapeptide, and the sequence code AEDG. A CAS registry number, 307297-39-8, is commonly cited for it, though catalogue entries should be checked against supplier documentation because mislabelled records occur. In its usual form the peptide carries free amino and carboxyl termini and is neither glycosylated nor lipidated. Researchers distinguish the defined tetrapeptide from epithalamin itself, a crude pineal preparation containing many peptides that is not chemically characterised.
Material supplied for laboratory use is normally a lyophilised white to off-white powder that dissolves readily in water and in isotonic saline. Lyophilised cakes are hygroscopic and should be equilibrated to room temperature before opening to limit condensation on the solid. Solutions are typically prepared at milligram-per-millilitre concentrations and divided into single-use aliquots, because repeated freeze–thaw cycles degrade short peptides. Aqueous solutions are far less stable than the dry powder, and identity is usually verified by mass spectrometry alongside purity estimation from reversed-phase high-performance liquid chromatography.
Epitalon is a synthetic linear tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and the calculated mass is approximately 390.35 g/mol. The compound is made by solid-phase peptide synthesis rather than extracted from tissue, although early work described it as a short fragment of a peptide fraction obtained from bovine pineal extract. In the research literature the spelling epitalon and the variant epithalone both appear, while AEDG is the standard code used in peptide nomenclature.
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.
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.
== Natural occurrence == NMT is naturally occurring in Acacia species like Acacia confusa (1.63%; Buchanan et al., 2007), Acacia obtusifolia (up to two-thirds of total alkaloid content), and Acacia simplicifolia (A. simplex; 1.44% in bark, 0.29% twigs; Pouet et al., 1976) and Desmanthus illinoensis (major component seasonally).
146C → 147N + e− + νe In this form of decay, the original element becomes a new chemical element in a process known as nuclear transmutation. This new element has an unchanged mass number A, but an atomic number Z that is increased by one. As in all nuclear decays, the decaying element (in this case 146C) is known as the parent nuclide while the resulting element (in this case 147N) is known as the daughter nuclide. Another example is the decay of hydrogen-3 (tritium) into helium-3 with a half-life of about 12.3 years:
Cancers are usually named using -carcinoma, -sarcoma or -blastoma as a suffix, with the Latin or Greek word for the organ or tissue of origin as the root. For example, the most common cancer of the liver parenchyma ("hepato-" = liver), arising from malignant epithelial cells ("carcinoma"), would be called a hepatocarcinoma, while a malignancy arising from primitive liver precursor cells is called a hepatoblastoma. Similarly, a cancer arising from malignant fat cells would be termed a liposarcoma. For some common cancers, the English organ name is used. For example, the most common type of breast cancer is called ductal carcinoma of the breast. Benign tumors (which are not cancers) are usually named using -oma as a suffix with the organ name as the root. For example, a benign tumor of smooth muscle cells is called a leiomyoma (the common name of this frequently occurring benign tumor in the uterus is fibroid). Confusingly, some types of cancer use the -noma suffix, examples including melanoma and seminoma. Some types of cancer are named for the size and shape of the cells under a microscope, such as giant cell carcinoma, spindle cell carcinoma, and small-cell carcinoma.
=== Sedation === The relative effectiveness of lorazepam in preventing new memory formation, along with its ability to reduce agitation and anxiety, makes it useful as premedication. It is given before a general anesthetic to reduce the amount of anesthetic required or before unpleasant awake procedures, such as in dentistry or endoscopies, to reduce anxiety, increase compliance, and induce anterograde amnesia for the procedure. Orally administered lorazepam is given 90 to 120 minutes before procedures, and intravenous lorazepam is given up to 10 minutes before procedures. Lorazepam is sometimes used as an alternative to midazolam in palliative sedation. In intensive care units, lorazepam is sometimes used to produce anxiolysis, hypnosis, and amnesia. Lorazepam is sometimes used for individuals receiving mechanical ventilation. In critically ill people, propofol has been found to be superior to lorazepam both in effectiveness and overall cost; as a result, the use of propofol for this indication is now encouraged, whereas the use of lorazepam is discouraged.
It is noteworthy that the genetic code for all organisms is basically the same, so that all living beings use the same 'genetic language'. In general, the introduction of new functional unnatural amino acids into proteins of living cells breaks the universality of the genetic language, which ideally leads to alternative life forms. Proteins are produced thanks to the translational system molecules, which decode the RNA messages into a string of amino acids. The translation of genetic information contained in messenger RNA (mRNA) into a protein is catalysed by ribosomes. Transfer RNAs (tRNA) are used as keys to decode the mRNA into its encoded polypeptide. The tRNA recognizes a specific three nucleotide codon in the mRNA with a complementary sequence called the anticodon on one of its loops. Each three-nucleotide codon is translated into one of twenty naturally occurring amino acids. There is at least one tRNA for any codon, and sometimes multiple codons code for the same amino acid. Many tRNAs are compatible with several codons. An enzyme called an aminoacyl tRNA synthetase covalently attaches the amino acid to the appropriate tRNA. Most cells have a different synthetase for each amino acid (20 or more synthetases). On the other hand, some bacteria have fewer than 20 aminoacyl tRNA synthetases, and introduce the "missing" amino acid(s) by modification of a structurally related amino acid by an aminotransferase enzyme.
Sources: en.wikipedia.org
After the incident, the commander of the 1st Brigade said: "I know burying people like that sounds pretty nasty, but it would be even nastier if we had to put our troops in the trenches and clean them out with bayonets." Secretary of Defense Dick Cheney did not mention the First Division's tactics in an interim report to Congress on Operation Desert Storm. In the report, Cheney acknowledged that 457 enemy soldiers were buried during the ground war.
Theo Wallimann (born 13 October 1946 in Alpnach, Obwalden, Switzerland) is a Swiss biologist who was research group leader and Adjunct-Professor at the Institute of Cell Biology ETH Zurich and later at the Institute of Molecular Health Science https://mhs.biol.ethz.ch/about-us/emeriti-formermembers/wallimann.html at the ETH Zurich at the Biology Department https://biol.ethz.ch/en/, of the ETH Zurich, Switzerland.
American Journal of Physical Anthropology International Journal of Osteoarchaeology HOMO: Journal of Comparative Human Biology International Journal of Paleopathology Bioarchaeology of the Near East Other
Three prime untranslated regions (3′UTRs) of mRNAs often contain regulatory sequences that post-transcriptionally cause RNAi. Such 3′-UTRs often contain both binding sites for miRNAs as well as for regulatory proteins. By binding to specific sites within the 3′-UTR, miRNAs can decrease gene expression of various mRNAs by either inhibiting translation or directly causing degradation of the transcript. The 3′-UTR also may have silencer regions that bind repressor proteins that inhibit the expression of a mRNA. The 3′-UTR often contains microRNA response elements (MREs). MREs are sequences to which miRNAs bind, primarily through evolutionarily conserved seed sequences six to eight nucleobases in length. These are prevalent motifs within 3′-UTRs. Among all regulatory motifs within the 3′-UTRs (e.g. including silencer regions), MREs make up about half of the motifs. As of 2023, the miRBase web site, an archive of miRNA sequences and annotations, listed 28,645 entries in 271 biologic species. Of these, 1,917 miRNAs were in annotated human miRNA loci. miRNAs were predicted to have an average of about four hundred target mRNAs (affecting expression of several hundred genes). Friedman et al. estimate that >45,000 miRNA target sites within human mRNA 3′UTRs are conserved above background levels, and >60% of human protein-coding genes have been under selective pressure to maintain pairing to miRNAs. Direct experiments show that a single miRNA can reduce the stability of hundreds of unique mRNAs.
== Gene and transcription == Obestatin is encoded by the same gene that encodes ghrelin, a peptide hormone. The mRNA produced from the GHRL gene has four exons. Five products of similar structure and function arise: the first is the 117-amino acid preproghrelin. (It is homologous to promotilin; both are members of the motilin family). It is cleaved to produce proghrelin which is cleaved to produce a 28-amino acid ghrelin (unacylated) and C-ghrelin(acylated). Obestatin is presumed to be cleaved from C-ghrelin.
Sources: en.wikipedia.org
Febris (fever in Latin) is the goddess of fever in Roman mythology. People with fevers would visit her temples. Tertiana and Quartana are the goddesses of tertian and quartan fevers of malaria in Roman mythology. Jvarasura (fever-demon in Hindi) is the personification of fever and disease in Hindu and Buddhist mythology.
Atherosclerosis – a hardening of the arteries Sickle cell disease – an inherited blood disorder that can block circulation throughout the body, primarily affecting people of sub-Saharan origin. Myasthenia gravis Systemic sclerosis Sinusitis Sjogren's Syndrome - an autoimmune disease that primarily attacks the lacrimal and salivary glands, but also impacts other organs such as the lungs, kidneys, liver, and nervous system.
== Epidemiology == Accurate epidemiological data on the prevalence of cachexia is lacking due to changing diagnostic criteria and under-identification of people with the disorder. It is estimated that cachexia from any disease is estimated to affect more than 5 million people in the United States. The prevalence of cachexia is growing and estimated at 1% of the population. The prevalence is lower in Asia but due to the larger population, represents a similar burden. Cachexia is also a significant problem in South America and Africa. In people with cancer, prevalence of cachexia was previously reported to range from 11% to 71%. Recent updates show that 33%-51.8% of people with cancer develop cachexia, though estimates vary widely and may be unreliable due to absence of consensus guidelines for diagnosis, variability in cancer populations, and variability in timing of diagnosis. Specifically, the highest rates were seen in older populations as well as those with upper gastrointestinal, colorectal, and lung cancers, respectively. The prevalence increases in advanced cancer stages, affecting up to 80% of terminal cancer cases. The most frequent diseases causing cachexia in the United States are: 1) cancer, 2) chronic heart failure, 3) chronic kidney disease, 4) COPD. Cachexia contributes to significant loss of function and healthcare utilization. Estimates suggest that cachexia accounted for 177,640 hospital stays in 2016 in the United States. Cachexia is considered the immediate cause of death of many people with cancer, estimated between 22 and 40%.
Since the formation of the Irish Free State in 1922 and subsequently in the Republic of Ireland, the legislature of Ireland is known as the Oireachtas, and consists of the president; the upper house, Seanad Éireann (or Senate); and lower house, Dáil Éireann (Assembly, or House of Representatives). They are functionally similar to other bicameral parliaments, with the lower house being significantly more influential and having more power over the creation of legislation. Elections to Dáil Éireann are held at least every five years using the single transferable vote; while elections to Seanad Éireann are restricted to members of both houses, elected members of local authorities, and alumni of National University of Ireland colleges. Eleven senators are nominated directly by the Taoiseach. A Member of Dáil Éireann is known as a Teachta Dála (TD) or "Deputy to the Dáil", and addressed as "Teachta" (Deputy), while a Member of the Seanad is known and addressed as Seanadóir (Senator). These titles are used much more commonly in English than the official Irish. A member of Parliament was the term used to refer to a member of the pre-1801 Irish House of Commons of the Parliament of Ireland. Irish members elected to the House of Commons of the United Kingdom of Great Britain and Ireland were also called members of Parliament from 1801 to 1922. Northern Ireland continues to elect MPs to the Parliament of the United Kingdom.
Sources: en.wikipedia.org
The solid is kept cold, dry and dark, typically at minus twenty degrees Celsius, in a sealed container with desiccant. Dissolved material is kept refrigerated and used promptly. Freezing and thawing a solution repeatedly is avoided because it accelerates degradation.
Reversed-phase chromatography with ultraviolet detection gives a purity percentage, while mass spectrometry confirms identity. Amino acid analysis checks the residue composition. Buyers typically request a certificate of analysis showing these measurements for the specific lot.
It is not authorised as a medicine in the United States or the European Union. Material is sold there as a research chemical or cosmetic ingredient. Some related short peptides are registered drugs in Russia, which is a distinct national situation rather than a general approval.
It is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, often abbreviated AEDG. The molecule is linear and contains no modified residues, so it is fully described by its sequence.