This is a working overview of Khavinson, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-05-20. Anything still debated is marked as such rather than presented as settled.
Stability of the tetrapeptide follows ordinary peptide chemistry rather than any unusual structural feature. The aspartate-glycine pair is prone to aspartimide formation under mildly basic or neutral conditions, and deamidation can follow, altering both mass and chromatographic retention. Dry lyophilised powder kept at or below minus twenty degrees Celsius is the usual handling recommendation, with repeated freeze-thaw cycles avoided. Once dissolved in neutral aqueous buffer, degradation proceeds over days to weeks depending on pH and temperature, while acidic conditions generally slow the aspartimide route. A formal stability-indicating study has not been published in the indexed literature.
Because epitalon has no pharmacopoeial monograph, quality assessment depends on supplier documentation and independent testing. Certificates of analysis typically report a purity figure from a single chromatographic run, a measured mass and sometimes an appearance description, but methods and acceptance criteria are not harmonised across vendors. Third-party laboratories can repeat identity and purity measurements, and mismatches between labelled and measured peptide content have been described for research peptides generally. What constitutes adequate identity confirmation for a molecule of this size stays an open question, since mass agreement alone does not separate closely related sequences.
Identity testing for epitalon relies on reversed-phase high-performance liquid chromatography for purity and mass spectrometry for mass confirmation. Because the sequence contains no tryptophan or tyrosine, ultraviolet detection at 280 nanometres is insensitive, so chromatographic methods usually monitor absorbance near 214 nanometres, where the peptide backbone absorbs. Electrospray ionisation or matrix-assisted laser desorption/ionisation then checks the intact mass against the expected value near 390 daltons. Peptide mapping or amino acid analysis after acid hydrolysis can supplement these measurements, although such confirmatory work is seldom reported on commercial certificates of analysis.
No national medicines regulator has approved epitalon as a therapeutic product. It is generally distributed as a research chemical, and in some jurisdictions selling peptides for human consumption without approval is restricted or prohibited. Certificates of analysis accompanying commercial material vary in which tests are performed, and independent verification of identity and purity is uncommon. Statements about anti-ageing or disease-prevention benefits on vendor pages are marketing claims rather than regulatory findings, a distinction that shapes how the compound is discussed in scientific and popular sources alike.
The most frequently cited laboratory finding is that AEDG increased telomerase activity and extended telomere length in cultured human somatic cells. That work used fetal fibroblast strains and reported changes in enzyme activity alongside altered division counts. Replication by unrelated groups has been limited, and the published record is largely a single-laboratory series rather than a multi-centre programme. The result supports a hypothesis about peptide influence on gene expression in cell culture; it does not by itself establish an effect on telomere length in living animals or in people.
| Property | Value | Notes |
|---|---|---|
| Analytical method | Reversed-phase HPLC | Purity determination, typically 214 nm |
| Mass confirmation | ESI or MALDI mass spectrometry | Compared with mass near 390 Da |
| Common synonyms | Epitalon, epithalon, AEDG | Naming differs between suppliers |
| Storage temperature | −20 °C or lower | Lyophilised powder, kept desiccated |
| Solution stability | Limited in neutral aqueous buffer | Aspartimide and hydrolysis pathways |
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.
Purity assessment of peptide reagents normally relies on reversed-phase high-performance liquid chromatography. A gradient of acetonitrile in water with trifluoroacetic acid, paired with a C18 stationary phase, separates the target tetrapeptide from truncated sequences and deletion analogues. Detection at 214 nanometres exploits absorbance of the peptide backbone, since the molecule contains no aromatic residue. Results are expressed as a percentage of total peak area. Values above ninety-five percent are typical for research-grade material, although reporting conventions vary between suppliers.
Identity confirmation uses mass spectrometry, usually electrospray ionisation in positive mode or matrix-assisted laser desorption. The protonated free peptide produces a signal near three hundred and ninety-one daltons, while salt adducts shift that value slightly. Tandem mass spectrometry or amino acid analysis supplies sequence-level confirmation, which a single mass measurement cannot. Peptides containing aspartate can cyclise into succinimide intermediates that hydrolyse to isoaspartate isomers of identical mass. Because those isomers are difficult to separate chromatographically, identity and purity results carry more weight when interpreted together.
Storage practice centres on limiting moisture, oxygen, and repeated temperature cycling. Freeze-dried powder is generally held desiccated at minus twenty degrees Celsius or colder and protected from light. Reconstituted solutions are markedly less stable, and the aspartate-glycine junction is prone to succinimide formation at neutral to mildly alkaline pH. Portioning material into single-use aliquots reduces degradation compared with repeated freeze-thaw cycles. Stability data specific to this tetrapeptide remain scarce, so most handling guidance is extrapolated from general peptide chemistry rather than measured directly.
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.
Reference material is normally supplied as a lyophilised powder in a sealed vial. Product literature typically recommends storage at minus twenty degrees Celsius or colder, protected from light and moisture. Freeze-thaw cycling is usually avoided because repeated condensation can introduce water into the vial. Working solutions are commonly prepared fresh, aliquoted, and kept cold for short periods rather than stored at ambient temperature. Labelling the date of opening helps track how long a vial has been in use.
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.
Different 2A peptides have different peptide-bond-skipping efficiencies, with T2A and P2A being the most efficient and F2A the least efficient. Therefore, up to 50% of F2A-linked proteins can in fact be produced as a fusion protein, which might cause some unpredictable outcomes, including a gain of function. One study reported that 2A sites cause the ribosome to fall off approximately 60% of the time, and that, together with ribosome read-through of about 10% for P2A and T2A, this results in reducing expression of the downstream peptide chain by about 70%. However, the level of drop-off detected in this study varied widely depending on the exact construct used, with some constructs showing little evidence of drop-off; furthermore, within a tri-cistronic transcript it reported a higher level of ribosome drop-off after one 2A sequence than after two 2As combined, which is at odds with a linear model of translation. IRES Recombinant DNA
==== In aqueous solution ==== Most neptunium coordination complexes known in solution involve the element in the +4, +5, and +6 oxidation states: only a few studies have been done on neptunium(III) and (VII) coordination complexes. For the former, NpX2+ and NpX+2 (X = Cl, Br) were obtained in 1966 in concentrated LiCl and LiBr solutions, respectively: for the latter, 1970 experiments discovered that the NpO3+2 ion could form sulfate complexes in acidic solutions, such as NpO2SO+4 and NpO2(SO4)−2; these were found to have higher stability constants than the neptunyl ion (NpO2+2). A great many complexes for the other neptunium oxidation states are known: the inorganic ligands involved are the halides, iodate, azide, nitride, nitrate, thiocyanate, sulfate, carbonate, chromate, and phosphate. Many organic ligands are known to be able to be used in neptunium coordination complexes: they include acetate, propionate, glycolate, lactate, oxalate, malonate, phthalate, mellitate, and citrate. Analogously to its neighbours, uranium and plutonium, the order of the neptunium ions in terms of complex formation ability is Np4+ > NpO2+2 ≥ Np3+ > NpO+2. (The relative order of the middle two neptunium ions depends on the ligands and solvents used.) The stability sequence for Np(IV), Np(V), and Np(VI) complexes with monovalent inorganic ligands is F− > H2PO−4 > SCN− > NO−3 > Cl− > ClO−4; the order for divalent inorganic ligands is CO2−3 > HPO2−4 > SO2−4. These follow the strengths of the corresponding acids. The divalent ligands are more strongly complexing than the monovalent ones.
== Reactions == Like other alkanes, pentanes are largely unreactive at standard room temperature and conditions - however, with sufficient activation energy (e.g., an open flame), they readily oxidize to form carbon dioxide and water:
The electoral system has seen little corruption since 1994. International Relations Minister and Cooperation Naledi Pandor has noted that during her term (starting 1994) a decline in political respectability had occurred in parliament, due to its members not engaging with one another in a courteous manner. She remarked that she felt undignified to be an observer of the crude behaviour, which also inhibited the conduct of successful politics.
== Medical uses == Artesunate is the first-line treatment for children or adults with severe malaria, usually in combination with another antimalarial drug. There is moderate-quality evidence that treatment with artesunate plus mefloquine is superior to treatment with artesunate plus amodiaquine or artesunate plus sulfadoxine-pyrimethamine. Artemisinin-based combination therapy may be used by mouth in persons that can tolerate it after 24 hours by injection. Artesunate is preferred over parenteral quinine for severe malaria treatment. Artesunate was shown to prevent more deaths from severe malaria than quinine in two large multicentre randomized controlled trials from Africa and Asia. A subsequent systematic review of seven randomized controlled trials found this improvement in survival rates to be consistent across all trials. Artesunate's efficacy is comparable to that of artemether, another artemisinin derivative, in treating adults for severe malaria caused by Plasmodium falciparum, though artesunate clears more parasites initially. Artesunate combination drugs have a number of advantages over artemether-based drugs in terms of its uptake and administration routes and may be more effective in treatment of severe and complicated malaria in children. Artesunate is also used to treat less-severe forms of malaria when it can be given orally. It has activity against P. ovale, P. malariae, and severe P. knowlesi. Artesunate + sulfadoxine/pyrimethamine for treatment of P. vivax is not recommended due to high rates of resistance.
Sources: en.wikipedia.org
== Interactions == Meropenem rapidly reduces serum concentrations of valproic acid. As a result, people who use valproic acid for epilepsy are at increased risk of seizures during treatment with meropenem. In situations where the use of meropenem cannot be avoided, prescription of an additional anticonvulsant should be considered.
He and Sophia Simmonds traveled abroad during the 1962–1963 academic year, returning just as the MBB department was being created and the Department of Biochemistry was entering a "crisis" because of the loss of experienced faculty (in particular, Fred Richards, the new head of MBB, and Ernie Pollard, who had left to head a biophysics department at Penn State).
== Signs and symptoms == Degenerative disc disease can result in lower back or upper neck pain. The amount of degeneration does not correlate well with the amount of pain patients experience. Many people experience no pain, while others with the same amount of damage have severe, chronic pain. Whether a patient experiences pain or not largely depends on the location of the affected disc and the amount of pressure that is being put on the spinal column and surrounding nerve roots. Degenerative disc disease is one of the most common sources of back pain and affects approximately 30 million people every year. With symptomatic degenerative disc disease, the pain can vary depending on the location of the affected disc. A degenerated disc in the lower back can result in lower back pain, sometimes radiating to the hips, and pain in the buttocks, thighs, or legs. If pressure is being placed on the nerves by exposed nucleus pulposus, sporadic tingling or weakness through the knees and legs can occur. A degenerated disc in the upper neck will often result in pain to the neck, arm, shoulders and hands; tingling in the fingers may also result if nerve impingement is occurring. Pain is most commonly felt or worsened by movements such as sitting, bending, lifting, and twisting. After an injury, some discs become painful because of inflammation and the pain comes and goes. Some people have nerve endings that penetrate more deeply into the anulus fibrosus (outer layer of the disc) than others, making discs more likely to generate pain.
== Further reading == Dean L (March 2017). "Amitriptyline Therapy and CYP2D6 and CYP2C19 Genotype". In Pratt VM, McLeod HL, Rubinstein WS, Scott SA, Dean LC, Kattman BL, et al. (eds.). Medical Genetics Summaries. National Center for Biotechnology Information (NCBI). PMID 28520380.
After Protestantism, individuals professing no religion are also a significant group, having exceeded 8% of the population according to the 2010 census. The cities of Boa Vista, Salvador, and Porto Velho have the greatest proportion of Irreligious residents in Brazil. Teresina, Fortaleza, and Florianópolis were the most Roman Catholic in the country. Greater Rio de Janeiro, not including the city proper, is the most irreligious and least Roman Catholic Brazilian periphery, while Greater Porto Alegre and Greater Fortaleza are on the opposite sides of the lists, respectively. In October 2009, the Brazilian Senate approved, and enacted by the President of Brazil in February 2010, an agreement with the Vatican, in which the Legal Statute of the Catholic Church in Brazil is recognized.
Sources: en.wikipedia.org
The molecule lacks aromatic residues, so it absorbs weakly near 280 nanometres, the wavelength applied to many other peptides. The peptide bond absorbs strongly below 220 nanometres, making 214 nanometres a practical compromise. Gradient methods must therefore use mobile phases with low ultraviolet absorbance to keep the baseline clean.
Neutral and slightly basic aqueous conditions promote aspartimide formation at the aspartate-glycine step, often followed by deamidation. Elevated temperature and repeated freeze-thaw cycles accelerate the loss. Acidic solutions and dry lyophilised powder are comparatively stable over short periods.
No monograph exists in the United States Pharmacopeia or the European Pharmacopoeia, and no widely distributed certified reference standard is available. Purity and identity therefore rest on supplier methods that are not harmonised. This absence is the main reason reported purities are difficult to compare between sources.
Small studies with human participants have been reported, chiefly in Russian-language journals, but they are limited in size and design. No large randomised controlled trial with published results is available.