If you have been reading about Khavinson 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 2026-06-24. Numbers and descriptions here follow the published literature rather than marketing material.
Material sold for research use varies widely in documented quality. A useful verification package includes a certificate of analysis that states peptide content rather than only net weight, the chromatographic method and column used, and a mass spectrum consistent with the expected mass. Independent testing by a third-party laboratory is occasionally reported. Statements of identity resting only on a supplier label provide little assurance, and the gap between nominal mass and actual peptide content can be substantial once counterions and residual water are counted.
Peptides of this size are generally stable as dry solids but degrade in solution over time. The principal routes are hydrolysis of the peptide backbone and oxidation, with hydrolysis favoured by elevated temperature and extreme pH. Aqueous solutions held at room temperature can show measurable loss of purity within days, while frozen aliquots are considerably more durable. Because the sequence contains neither cysteine nor methionine, oxidation is less of a concern than for many other peptides, but pH control during handling still matters.
Typical storage for the lyophilized powder is −20 °C or lower, in a sealed container protected from light and moisture. Hygroscopic material should be allowed to equilibrate to room temperature before the vial is opened, which limits condensation on the contents. Working solutions are commonly divided into single-use aliquots and frozen to avoid repeated freeze-thaw cycles. Dilute solutions are more prone to adsorption onto plastic surfaces and to loss during filtration, so procedures that minimize transfers and use low-binding labware are preferable.
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 is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and its calculated monoisotopic mass is approximately 390.35 daltons. The compound does not occur naturally as a free peptide; it is produced by solid-phase peptide synthesis. Because it contains two acidic residues and no basic residues, the neutral form carries a net negative charge at physiological pH. This charge profile influences how the peptide behaves in solution and during chromatographic analysis.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilized solid |
| Solubility | Freely soluble in water | Also dissolves in polar organic solvents |
| Typical storage temperature | −20 °C or below | Sealed, desiccated, protected from light |
| Primary purity assay | Reversed-phase HPLC | Ultraviolet detection near 214 nm |
| Identity confirmation | Mass spectrometry | Electrospray ionization commonly used |
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.
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.
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.
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.
A disintegrin and metalloproteinase with thrombospondin motifs 7 (ADAMTS7) is an enzyme that in humans is encoded by the ADAMTS7 gene on chromosome 15. It is ubiquitously expressed in many tissues and cell types. This enzyme was historically reported to catalyze the degradation of cartilage oligomeric matrix protein (COMP), though subsequent studies using purified proteins and unbiased mass spectrometry found that ADAMTS7 does not cleave COMP. ADAMTS7 has been associated with cancer and arthritis in multiple tissue types. The ADAMTS7 gene is a well-established genetic susceptibility locus for coronary artery disease. The ADAMTS7 gene resides on chromosome 15 at the band 15q24.2 and contains 25 exons.
In humans, phytoestrogens are digested in the small intestine, poorly absorbed into the circulatory system, circulate in plasma, and are excreted in the urine. Metabolic influence is different from that of grazing animals due to the differences between ruminant versus monogastric digestive systems. As of 2020, there is insufficient clinical evidence to determine that phytoestrogens have effects in humans.
Zenobi-Wong works in the area of tissue engineering, in particular for cartilage regeneration. She develops functional biomaterials which mimic the extracellular matrix. The biofabrication techniques used to develop these materials include electrospinning, casting, two-photon polymerization and bioprinting. Zenobi-Wong holds four licensed patents in the fields of tissue engineering, tissue engineering techniques, and gene expression assays. She was one of the originators of the MSc Biomedical Engineering program at ETH Zürich, and developed several graduate level courses in tissue engineering and biomedical engineering. Zenobi-Wong currently serves as President of the Swiss Society for Biomaterials and Regenerative Medicine, and as secretary general of the International Society of Biofabrication. ETH Zürich Department of Health Sciences and Technology - Tissue Engineering and Biofabrication Group Marcy Zenobi-Wong publications indexed by Google Scholar
=== Physical and atomic === Roentgenium is expected to be a solid under normal conditions and to crystallize in the body-centered cubic structure, unlike its lighter congeners which crystallize in the face-centered cubic structure, due to its being expected to have different electron charge densities from them. It should be a very heavy metal with a density of around 22–24 g/cm3; in comparison, the densest known element that has had its density measured, osmium, has a density of 22.61 g/cm3. The atomic radius of roentgenium is expected to be around 114 pm.
Sources: en.wikipedia.org
In more recent years, the party has attempted to win votes from Black South Africans and as a result, Black support for the DA has risen over the past several years, going from 1% to 6%. The DA is a liberal party that favours free-market policies. The DA was allotted 89 seats in parliament after the 2014 general election, but the party's seat total decreased to 84 seats following the 2019 general election. The DA has been part of the government of South Africa since the 2024 general election, having joined the Government of National Unity (GNU), and President Cyril Ramaphosa's Third Cabinet. The DA stated that one of its main aims for joining the GNU was keeping rival parties EFF and MK out of the government; a goal which was achieved as per the eventual composition of the GNU. As of May 2025, the party holds 6 ministry seats, and 6 deputy ministry seats in parliament. Economic Freedom Fighters The EFF emerged eight months before the 2014 general election and won 25 seats in parliament. After the 2019 general elections, the EFF increased their seats in parliament to 44, the only party of the top three parties that achieved an increase of members in parliament. The EFF is a far-left revolutionary socialist political party, advocating for land expropriation and for an end to corruption within parliament. Inkatha Freedom Party The IFP, which was formed in 1990 was the successor to the former government in the now-defunct Kwazulu Bantustan, traditionally draws its support from the Zulu people. It has however made inroads into the minority electorate of Whites and Indians.
== Diversity == There are a large number of different odor receptors, with as many as 2,000 in the mammalian genome which, depending on the species represents up to 5% of the coding-genes in the genome. However, not all of these potential odor receptor genes are expressed and functional. According to an analysis of data derived from the Human Genome Project, humans have approximately 400 functional genes coding for olfactory receptors, and the remaining 600 candidates are pseudogenes. The reason for the large number of different odor receptors is to provide a system for discriminating between as many different odors as possible. Even so, each odor receptor does not detect a single odor. Rather each individual odor receptor is broadly tuned to be activated by a number of similar odorant structures. Analogous to the immune system, the diversity that exists within the olfactory receptor family allows molecules that have never been encountered before to be characterized. However, unlike the immune system, which generates diversity through in-situ recombination, every single olfactory receptor is translated from a specific gene; hence the large portion of the genome devoted to encoding OR genes. Furthermore, most odors activate more than one type of odor receptor. Since the number of combinations and permutations of olfactory receptors is very large, the olfactory receptor system is capable of detecting and distinguishing between a very large number of odorant molecules.
=== 2007 === Reconstitution of a Cambodian traditional wood kiln 40 000 Litres. This kiln has mobilized 15 people for two months + 5000h work. The original kiln has been discovered at Phnom Kulen. 1st International Khmer Ceramics festival & Conference. The conference is held at the CKS center for Khmer study.
Sources: en.wikipedia.org
=== Modern times === The university hired its first African-American faculty member, Vivian Cox, in 1967. Three professors were murdered at the school in a shooting in 2002. The perpetrator, who then shot himself, was a student who had failed out of the school. He mailed a 22-page letter to the Arizona Daily Star announcing his reasons, naming two of the killed professors in the letter; following the shooting, the Daily Star made the controversial decision to publish the letter. On April 17, 2020, the University of Arizona announced temporary pay cuts and furloughs to its 15,000 employees as its Tucson campus shut down due to the COVID-19 pandemic. All employees making up to $150,000 per year were furloughed, with the length determined by each employees' salary. For employees making more than $150,000 per year, pay cuts of 17% or 20% were instituted. Also in 2020, the University of Arizona announced it had purchased Ashford University from Zovio and renamed it The University of Arizona Global Campus. The purchase was heavily criticized, particularly by University of Arizona faculty members. As Ashford was being purchased by the University of Arizona, it was the subject of an investigation by the Attorney General of Massachusetts, a lawsuit from the Attorney General of California, and a formal notification of concern from the university's accreditor. A university professor was murdered on campus in October 2022, by a former student. Following the crime, the university commissioned an independent investigation of campus safety.
=== Examples === Black-box (stimulus/response) loggers: A flight data recorder (FDR) is a piece of recording equipment used to collect specific aircraft performance data. The term may also be used, albeit less accurately, to describe the cockpit voice recorder (CVR), another type of data recording device found on board aircraft. An event data recorder (EDR) is a device installed by the manufacturer in some automobiles which collects and stores various data during the time-frame immediately before and after a crash. A voyage data recorder (VDR) is a data recording system designed to collect data from various sensors on board a ship. A train event recorder is a device that records data about the operation of train controls and performance in response to those controls and other train control systems. An accident data recorder (ADR) is a device for triggering accidents or incidents in most kind of land vehicles and recording the relevant data. In automobiles, all diagnostic trouble codes (DTCs) are logged in engine control units (ECUs) so that at the time of service of a vehicle, a service engineer will read all the DTCs using Tech-2 or similar tools connected to the on-board diagnostics port, and will come to know problems occurred in the vehicle. Sometimes a small OBD data logger is plugged into the same port to continuously record vehicle data. In embedded system and digital electronics design, specialized high-speed digital data logger help overcome the limitations of more traditional instruments such as the oscilloscope and the logic analyzer.
The Indian Plate survives as peninsular India, the oldest and geologically most stable part of the country. It extends as far north as the Satpura and Vindhya ranges in central India. These parallel chains run from the Arabian Sea coast in Gujarat in the west to the coal-rich Chota Nagpur Plateau in Jharkhand in the east. To the south, the peninsular landmass, the Deccan Plateau, is flanked on the west and east by coastal ranges known as Western and Eastern Ghats; the plateau contains the country's oldest rock formations, some over one billion years old. Geographically, India lies to the north of the equator between 6° 44′ and 35° 30′ north latitude and 68° 7′ and 97° 25′ east longitude. Major Himalayan-origin rivers that substantially flow through India include the Ganges and the Brahmaputra, both of which drain into the Bay of Bengal. Important tributaries of the Ganges include the Yamuna and the Kosi. The Kosi's extremely low gradient, caused by long-term silt deposition, leads to severe floods and course changes. Major peninsular rivers, whose steeper gradients prevent extensive flooding, include the Godavari, the Mahanadi, the Kaveri, and the Krishna, which also drain into the Bay of Bengal; and the Narmada and the Tapti, which drain into the Arabian Sea. India's coastline measures 7,517 kilometres (4,700 mi) in length; of this distance, 5,423 kilometres (3,400 mi) belong to peninsular India and 2,094 kilometres (1,300 mi) to the Andaman, Nicobar, and Lakshadweep island chains.
Sources: en.wikipedia.org
The powder is normally kept at −20 °C or below in a sealed, moisture-protected container. Letting the vial reach room temperature before opening helps prevent condensation on the contents.
Reversed-phase HPLC with ultraviolet detection is the usual approach, often paired with mass spectrometry. Together the two methods address both chromatographic purity and molecular identity.
Differences arise from the analytical method, the detection wavelength, and whether the number refers to the peptide or to total powder mass. Counterion and water content can lower the actual peptide fraction considerably.
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.