If you have been reading about certificate of analysis 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.
Last reviewed on 2025-12-11. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Computed for the free acid of Ala-Glu-Asp-Gly |
| Molecular mass | About 390.35 g/mol | Free peptide; salt forms shift the value |
| Appearance | White to off-white solid | Typical of short peptides after freeze-drying |
| Solubility class | Freely soluble in water | Aqueous buffers are also commonly used |
| Common synonyms | Epitalon, epithalone, AEDG | AEDG is the single-letter sequence |
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.
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.
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.
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.
== Pharmacokinetics == Most wrinkle fillers are temporary because they are eventually metabolized by the body. Some people may need more than one injection to achieve the wrinkle-smoothing effect. The effect lasts for about six months. Results depend on health of the skin, skill of the health care provider, and the type of filler used. Regardless of material (whether synthetic or organic) filler duration is highly dependent on amount of activity in the body area where it is injected. Exercise and high intensity activities such as manual labor can stimulate blood flow and shorten the lifespan of fillers.
Primer and bonding resin are applied to etched dentin, they penetrate the intertubular dentin, forming hybrid layer. They also penetrate and polymerize in open dentinal tubules, forming resin tags. Moist bonding technique has been shown repeatedly to enhance bond strengths of etch-and-rinse adhesives because water preserves the porosity of collagen network for monomer interdiffusion.
Robert Martin Culp (August 16, 1930 – March 24, 2010) was an American actor and screenwriter widely known for his work in television. Culp earned an international reputation for his role as Kelly Robinson on I Spy (1965–1968), the espionage television series in which he and co-star Bill Cosby played secret agents. Before this, he starred in the CBS/Four Star Western series Trackdown as Texas Ranger Hoby Gilman in 71 episodes from 1957 to 1959. The 1980s brought him back to television as FBI Agent Bill Maxwell on The Greatest American Hero. Later, he had a recurring role as Warren Whelan on Everybody Loves Raymond, and was a voice actor for various video games, including Half-Life 2. Culp gave hundreds of performances in a career spanning more than 50 years.
=== Outcome and management === The liver injury due to the carbapenems is usually mild and self-limited. Rarely, the carbapenems can cause a clinically apparent acute cholestatic hepatitis that is usually self-limiting and not requiring therapy or intervention. In patients with vanishing bile duct syndrome, corticosteroids are often used but have not been shown to be beneficial and are best avoided. Some patients may benefit from symptomatic therapy of the pruritus associated with cholestasis using antihistamines, ursodiol, or cholestyramine. Little information is available on possible cross-sensitivity to liver injury among the different betalactam antibiotics, but patients with clinically apparent liver injury due to imipenem should probably avoid the other carbapenems.
Sources: en.wikipedia.org
Randomized: Each study subject is randomly assigned to receive either the study treatment or a placebo. Blind: The subjects involved in the study do not know which study treatment they receive. If the study is double-blind, the researchers also do not know which treatment a subject receives. This intent is to prevent researchers from treating the two groups differently. A form of double-blind study called a "double-dummy" design allows additional insurance against bias. In this kind of study, all patients are given both placebo and active doses in alternating periods. Placebo-controlled: The use of a placebo (fake treatment) allows the researchers to isolate the effect of the study treatment from the placebo effect. Clinical studies having small numbers of subjects may be "sponsored" by single researchers or a small group of researchers, and are designed to test simple questions or feasibility to expand the research for a more comprehensive randomized controlled trial. Clinical studies can be "sponsored" (financed and organized) by academic institutions, pharmaceutical companies, government entities and even private groups. Trials are conducted for new drugs, biotechnology, diagnostic assays or medical devices to determine their safety and efficacy prior to being submitted for regulatory review that would determine market approval.
Navacaprant (developmental code names include BTRX-335140, BTRX-140, CYM-53093, NMRA-335140, and NMRA-140) is a selective κ-opioid receptor (KOR) antagonist which is under development for the treatment of major depressive disorder and bipolar depression. It was originated by BlackThorn Therapeutics and is being developed by Neumora Therapeutics. As of February 2025, navacaprant is in phase 3 clinical trials for major depressive disorder. In January 2025, it was disclosed that navacaprant had failed to show effectiveness for major depressive disorder in a phase 3 trial. Upon this announcement, the stock price of Neumora Therapeutics decreased by 80%.
== BP in Positron Emission Tomography == BP is a pivotal measure in the use of positron emission tomography (PET) to measure the density of "available" receptors, e.g. to assess the occupancy by drugs or to characterize neuropsychiatric diseases (yet, one should keep in mind that binding potential is a combined measure that depends on receptor density as well as on affinity). An overview of the related methodology is e.g. given in Laruelle et al. (2002). Estimating BP with PET usually requires that a reference tissue is available. A reference tissue has negligible receptor density and its distribution volume should be the same as the distribution volume in the target region if all receptors were blocked. Although the BP can be measured in a relatively unbiased way by measuring the whole time course of labelled ligand association and blood radioactivity, this is practically not always necessary. Two other common measures have been derived, which involve assumptions, but result in measures that should correlate with BP:
For some polyprotic acids, dissociation (or association) occurs at more than one nonequivalent site, and the observed macroscopic equilibrium constant, or macro-constant, is a combination of micro-constants involving distinct species. When one reactant forms two products in parallel, the macro-constant is a sum of two micro-constants,
Encouraging healthy habits early in life and addressing fear-avoidance behaviors in children with JIA can enhance both musculoskeletal and cardiovascular health. A Cochrane meta-analysis looking at existing RCTs showed in all studies that exercise does not have a detrimental effect on JIA. In fact, there is evidence to show that both low and high-intensity exercise programs result in improved physical function and reduced pain in children with JIA. Guidelines indicate that children with JIA should be encouraged to be physically active and can safely participate in sports without disease exacerbation. Those with actively inflamed joints should limit activities within pain limits, then gradually return to full activity following a disease flare. Studies found that a 12-week exercise program of weight-bearing exercise plus standardized muscle strengthening exercises for children with JIA led to significant improvements in bone mineral density, bringing measurements for children with JIA within the reference range of healthy children. It may be necessary to use aids like splints or casts to correct biomechanics, but prolonged splinting and casting are now rarely indicated for children with JIA. Joint injections of steroids may be helpful for children with JIA.
Sources: en.wikipedia.org
Many industrially important compounds, such as ammonia, nitric acid, organic nitrates (propellants and explosives), and cyanides, contain nitrogen. The extremely strong triple bond in elemental nitrogen (N≡N), the second strongest bond in any diatomic molecule after carbon monoxide (CO), dominates nitrogen chemistry. This causes difficulty for both organisms and industry in converting N2 into useful compounds, but at the same time it means that burning, exploding, or decomposing nitrogen compounds to form nitrogen gas releases large amounts of often useful energy. Synthetically produced ammonia and nitrates are key industrial fertilisers, and fertiliser nitrates are key pollutants in the eutrophication of water systems. Apart from its use in fertilisers and energy stores, nitrogen is a constituent of organic compounds as diverse as aramids used in high-strength fabric and cyanoacrylate used in superglue. Nitrogen occurs in all organisms, primarily in amino acids (and thus proteins), in the nucleic acids (DNA and RNA) and in the energy transfer molecule adenosine triphosphate. The human body contains about 3% nitrogen by mass, the fourth most abundant element in the body after oxygen, carbon, and hydrogen. The nitrogen cycle describes the movement of the element from the air, into the biosphere and organic compounds, then back into the atmosphere. Nitrogen is a constituent of every major pharmacological drug class, including antibiotics.
In 2001, Otto Reich, a hardline Republican Anti-Castro Cuban-born exile in the United States, who had formerly been involved in the Iran–Contra affair, was at the time the Assistant Secretary of State for Western Hemisphere Affairs. He approached Marc Wachtenheim from the Pan American Development Foundation, a subcontractor for the United States Agency for International Development (USAID), to hatch a development program to reopen Cuba, and then developed a covert influence campaign that might lead to conditions that could foment revolution there. They decided that because Freemasonry had been so present in Cuban society, to cultivate the Grand Lodge of Cuba. In 2001, Marc Wachtenheim brought Grand Master Collera Venta to Washington, D.C. to meet with Otto Reich. The staff of the United States Interests Section in Havana were well aware of the fact that Grand Master Collera Venta was a Cuban counterintelligence officer at the State Security Unit (DSE) (Spanish: Departamento de Seguridad del Estado) who went by the codename Agente Gerardo, and had been a spy for over 25 years. They did not share this information with USAID, nor any of their subcontractors, because the subcontractors didn't share their own plans with the Interests Section. The greater staff of the US diplomatic mission in Havana were aware of Collera Venta's true employment by 2007 – but they still did not inform USAID. Collera Venta later told CNN: "My job was to discover and neutralize these plans against my country."
degree and to have substantial published research. Transfer to general practice or a less favoured specialty could be made at any stage along this pathway: Lord Moran famously referred to general practitioners as those who had "fallen off the ladder". There were also permanent non-training posts at sub-consultant level: previously senior hospital medical officer and medical assistant (both obsolete) and now staff grade, specialty doctor and associate specialist. The regulations did not call for much experience or any higher qualifications, but in practice both were common, and these grades had high proportions of overseas graduates, ethnic minorities and women. Research fellows and PhD candidates were often clinical assistants, but a few were senior or specialist registrars. A large number of "Trust Grade" posts had been created by the new NHS trusts for the sake of the routine work, and many juniors had to spend time in these posts before moving between the new training grades, although no educational or training credit was given for them. Holders of these posts might work at various levels, sharing duties with a junior or middle grade practitioner or with a consultant. In 2005, the structure of medical training was reformed when the Modernising Medical Careers (MMC) reform programme was instituted. House officers and the first year of senior house officer jobs were replaced by a compulsory two-year foundation training programme, followed by competitive entry into a formal specialty-based training programme.
=== Phase 1 === NTX-1955 (RO-7308480) – γ1 subunit-containing GABAA receptor positive allosteric modulator SPT-320 (LYT-320) – agomelatine prodrug (melatonin receptor agonist and weak serotonin 5-HT2B and 5-HT2C receptor antagonist)
Sources: en.wikipedia.org
It is a four-amino-acid peptide with the sequence alanine-glutamate-aspartate-glycine. The chain is unmodified and contains only standard proteinogenic residues, which makes it straightforward to produce by solid-phase synthesis and to characterise by standard peptide methods.
Epitalon and epithalon both circulate, and the difference reflects transliteration of a name coined in Russian-language publications. Reference to the extract it derives from, epithalamin, explains the shared stem. Databases and suppliers are inconsistent, so a search for one spelling alone may miss relevant entries.
No. Epithalamin is a multi-component preparation obtained from pineal tissue, and its exact composition is not fully characterised. Epitalon is a single defined tetrapeptide described as a short synthetic counterpart of that extract, so the two are related in origin but not interchangeable in identity.
Mass spectrometry provides the identity check, because the observed mass is compared with the theoretical mass of the AEDG sequence. Chromatography separates and quantifies impurities but does not by itself prove which peptide is present. The two techniques are normally used together.