Everything below concerns lyophilisation. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-01-02. Where a claim depends on a specific study, the study is described rather than over-claimed.
Epitalon is a synthetic tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. Its design traces to epithalamin, a peptide fraction prepared from bovine pineal gland extracts that researchers in Saint Petersburg began investigating in the 1970s. The compound has a molecular formula of C14H22N4O9 and a nominal molecular mass near 390 daltons. It holds no approved drug status in the United States or the European Union, and material sold under this name is generally offered as a research chemical rather than a finished pharmaceutical product.
Proposed mechanisms centre on cell-culture observations rather than a defined receptor interaction. Several reports describe increased expression of the telomerase catalytic subunit after exposure of cultured human cells, and the authors attributed the effect to short peptide fragments entering the nucleus and influencing gene transcription. No receptor for the tetrapeptide has been identified, and the free peptide is expected to be degraded rapidly by plasma peptidases. Whether any measurable fraction reaches intact tissues after administration remains an unresolved question rather than an established finding.
The published literature is dominated by a small number of research groups, much of it in Russian-language journals, and independent replication outside those groups is limited. Studies are typically small, use cultured cells or rodent models, and report endpoints that differ between papers, which makes comparison difficult. Large randomised human trials have not appeared in the indexed literature. Questions about absorption, distribution and clearance are therefore still treated as open in reviews that mention the compound.
Lyophilised epitalon is generally held at minus twenty degrees Celsius in a sealed container kept dry and dark. Cooler conditions are sometimes recommended for long-term archives. The solid takes up moisture readily enough that repeated opening of a vial introduces water, so dividing a batch into smaller portions before storage lowers degradation risk. Aqueous solutions are less durable than the dry powder and are usually prepared shortly before use, then kept cold and shielded from light to slow hydrolysis and oxidation.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Synthetic tetrapeptide, four residues |
| Nominal mass | Approximately 390 Da | Free peptide; salt forms differ |
| Appearance | White to off-white powder | Commonly supplied lyophilised |
| Solubility class | Freely soluble in water | Also dissolves in aqueous buffer |
| Typical storage | −20 °C, desiccated | Cold packs used during transport |
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.
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.
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.
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 parent extract epithalamin was characterised as a low-molecular-weight fraction of pineal tissue rather than a single defined chemical entity. Researchers fractionated it and tested successive fragments for activity, a screening approach typical of peptide discovery work in that era. Epitalon emerged from that process as one of the shorter sequences of interest. Because the original extract was never fully resolved into individual components, claims about which constituent drives a given effect rest on inference. This distinction matters when reading older reports that attribute extract observations to the tetrapeptide itself.
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.
== Uses == In the 1970s and 1980s, the proportionately largest use of these polymers was in water treatment. The next major application by weight is additives for pulp processing and papermaking. About 30% of polyacrylamide is used in the oil and mineral industries.
=== Distribution === Progesterone crosses the blood–brain barrier. In terms of plasma protein binding, progesterone is 98 to 99% protein-bound in the circulation. It is bound 80% to albumin, 18% to corticosteroid-binding globulin, and less than 1% to sex hormone-binding globulin, with the remaining fraction of 1 to 2% circulating freely or unbound.
=== Awards and honours === As of 2015, Sanger is one of the only two people to have been awarded the Nobel Prize in Chemistry twice (the other being Karl Barry Sharpless in 2001 and 2022), and one of only five two-time Nobel laureates: The other four were Marie Curie (Physics, 1903 and Chemistry, 1911), Linus Pauling (Chemistry, 1954 and Peace, 1962), John Bardeen (twice Physics, 1956 and 1972), and Karl Barry Sharpless (twice Chemistry, 2001 and 2022).
Therapeutic monoclonal antibodies act through multiple mechanisms, such as blocking of targeted molecule functions, inducing apoptosis in cells which express the target, or by modulating signalling pathways.
Sources: en.wikipedia.org
Modimelanotide (INN; development code AP-214, ABT-719, and ZP-1480) is a melanocortinergic peptide drug derived from α-melanocyte-stimulating hormone (α-MSH) which was under development by, at different times, Action Pharma, Abbott Laboratories, AbbVie, and Zealand for the treatment of acute kidney injury. It acts as a non-selective melanocortin receptor agonist, with IC50 values of 2.9 nM, 1.9 nM, 3.7 nM, and 110 nM at the MC1, MC3, MC4, and MC5 receptors. Modimelanotide failed clinical trials for acute kidney injury despite showing efficacy in animal models, and development was not further pursued.
On some narrow-gauge lines in Europe, and on the Paris Metro, a simplified version of the loose-coupler is used, consisting of a single central buffer with a chain underneath. Sometimes there are two chains, one on each side of the coupler. The chain usually contains a screw-adjustable link to allow close coupling. These variants are also used elsewhere. On sharp curves, a single centre buffer is less likely to be subject to buffer-locking. The Eritrean Railway also uses a centre buffer and chain coupler.
=== Season 3: 2009 === The title for the season is: 诸子百家 Zhu Zi Bai Jia (Masters of the Hundreds of Schools), the word "Hundred" here means many instead of an accurate number. The expression is the classical description for the diverse intellectual life of the Warring States period of Chinese history. The third season was finished in 2009 and aired in 2010, it consists of 34 episodes.
USDA RDA chart in PDF format Archived 9 November 2021 at the Wayback Machine Health Canada Dietary Reference Intakes Reference Chart for Vitamins NIH Office of Dietary Supplements: Fact Sheets Archived 16 September 2008 at the Wayback Machine "Vitamins and minerals". nhs.uk. 23 October 2017.
the third technological development was the double lumen breast implant device, a double-cavity prosthesis composed of a silicone breast implant contained within a saline breast implant. The two-fold, technical goal was: (i) the cosmetic benefits of silicone-gel (the inner lumen) enclosed in saline solution (the outer lumen); (ii) a breast implant device the volume of which is post-operatively adjustable. Nevertheless, the more complex design of the double-lumen breast implant suffered a device-failure rate greater than that of single-lumen breast implants. The contemporary versions of second-generation breast implant devices (presented in 1984) are the "Becker Expandable" models of breast implant, which are primarily used for breast reconstruction.
Sources: en.wikipedia.org
== Spectrophotometry in Print == To those involved in the graphics field, color is a property of the surface of a given object under a certain illumination or light source. In order to reproduce the same color or design, the sample color must be measured. This is where spectrophotometers come in. Different types of spectrophotometers are used for different printing technologies. Offset presses use handheld and closed-loop scanning spectrophotometers. Flexo, rotogravure, screen printers, and digital presses use handheld and inline spectrophotometers. The human eye, as well as the brain, can struggle with color perception/vision. Some individuals may experience color blindness, while others will notice that their eyes become strained and less apt to see color effectively as the day goes on. To combat these issues, spectrophotometers can be used to measure color targets and control color strips. In the printing industry, the three types of spectrophotometers are: Handheld, handheld with informational displays, and automated. Another device is a spectrodensitometer, which can calculate density readings from spectral values. From its definition, a spectrodensitometer is "A spectrally based densitometer that combines the functions of a spectrophotometer, colorimeter, and densitometer."
The biosynthetic gene clusters encoding the biological machinery responsible for producing enediynes have been cloned and characterized for five 9-membered enediynes (C-1027, neocarzinostatin, maduropeptin, sporolides, and kedarcidin), and three 10-membered enediynes (calicheamicin, esperamicin, and dynemicin). Comparative studies of these biosynthetic apparatus have shown that the enediyne core of these molecules is initiated by a common enzyme, enediyne polyketide synthase (PKS). The polyene product of this enzyme is then divergently elaborated into the 9- or 10-membered cores of the enediynes depending on the specific PKS-associated enzymes present. A convergent biosynthetic strategy is then employed by the producing organisms, whereby the varying peripheral appendages of the enediynes are attached to the core structure to furnish the final product. In 2013, the successful cloning and characterization of the kedarcidin biosynthetic cluster ("ked") was reported by researchers at the Scripps Research Institute and the University of Wisconsin-Madison. The identity of this cloned gene cluster was corroborated by kedA, a gene in the cluster that encodes the previously isolated kedarcidin apoprotein, as well as kedE and kedE10, the co-expression of which in E. coli led to the formation of a signature heptaene product previously implicated in enediyne core biosynthesis.
=== RMF, RaiA, and HPF === Three proteins, RMF, RaiA, and HPF, are only found in the large class of bacteria gammaproteobacteria. RMF (Ribosome modulation factor) is a small protein, typically produced under nutrient starvation and stress conditions, that is the main factor in the formation of 100S ribosomes. During the formation process, RMF binds together 70S (standard) ribosomes to form 90S ribosome dimers. These 90S dimers are converted by HPF (hibernation promoting factor) to form mature 100S dimers. A third protein, RaiA (ribosome-associated inhibitor A) is thought to both inactivate 70S ribosomes alone and stabilize them, preventing them from being converted into 100S ribosomes. Most non-gammaproteobacteria, as well as some plant plastids, instead contain a HPF homologue that can form 100S ribosomes by itself.
Heseltine resigned as managing director of Haymarket on his promotion to principal opposition spokesman on transport in 1969, although he continued as chairman of the board until he became a minister in 1970, at which point he resigned from the board altogether, whilst remaining a major shareholder.
Vaccines typically contain attenuated, inactivated or dead organisms or purified products derived from them. There are several types of vaccines in use. These represent different strategies used to try to reduce the risk of illness while retaining the ability to induce a beneficial immune response.
Sources: en.wikipedia.org
No. Epithalamin is a heterogeneous peptide fraction obtained from pineal gland extract and contains many components. Epitalon is a single synthetic tetrapeptide with the sequence Ala-Glu-Asp-Gly. Researchers synthesised the shorter peptide while attempting to identify active sequences within the extract.
No endogenous peptide with this exact sequence has been described as a circulating hormone or signalling molecule. The tetrapeptide was designed as a synthetic analogue based on fragments observed in pineal preparations. Any activity discussed in the literature therefore refers to administered material rather than to a natural pool of the compound.
It is not an approved medicine in major jurisdictions and does not appear in the major pharmacopoeias. Material is usually distributed as a research chemical or laboratory reagent. Such labelling places handling responsibility on the purchaser and does not indicate that a regulatory body has reviewed the substance.
The usual approach is reversed-phase HPLC with ultraviolet detection, reported as a percentage of total peak area. Mass spectrometry is used alongside chromatography to confirm identity rather than purity alone.