certificate of analysis comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-05-16. Where a claim depends on a specific study, the study is described rather than over-claimed.
The compound is generally described as a synthetic analogue of a fragment isolated from a pineal gland extract. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology introduced it during the 1980s and 1990s while studying short peptides from animal tissue. The original extract, called epithalamin, is a heterogeneous mixture, whereas epitalon is a single defined sequence. That distinction matters because findings reported for the extract are not automatically findings about the pure tetrapeptide, and claims about broader biological effects remain a separate question from the chemical identity described here.
Residue composition is the property that most cleanly separates verified material from mislabelled samples. Alanine, glutamate, aspartate and glycine appear in that order from the N-terminus, and the two acidic residues sit in the middle of the chain. Because the peptide is short, it can be produced by solid-phase synthesis and characterised by mass spectrometry without ambiguity. Any reported sample whose measured mass departs substantially from 390 daltons is a different compound or a degraded mixture rather than epitalon.
Epitalon is a synthetic tetrapeptide whose four residues are alanine, glutamate, aspartate and glycine, commonly abbreviated AEDG. Its molecular formula is C14H22N4O9 and its monoisotopic mass is near 390.35 daltons. The peptide carries two acidic side chains, so it is neutral to negatively charged in most aqueous buffers. Published reference summaries usually list it under both spellings, epitalon and epithalon, and treat the two names as the same material.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Derived from the four constituent residues |
| Molecular mass | About 390.35 Da | Monoisotopic value, confirmed by mass spectrometry |
| Residue sequence | Ala-Glu-Asp-Gly | Read from the N-terminus to the C-terminus |
| Common synonyms | Epithalon; AEDG | Both forms appear in reference catalogues |
| Net charge near neutral pH | Negative | Two acidic side chains give a low isoelectric point |
The four residues give epitalon a molecular formula of C14H22N4O9 and a molecular weight near 390.35 daltons. The presence of two acidic residues, glutamate and aspartate, makes the free peptide strongly acidic, while the alanine and glycine ends provide neutral, nonpolar character. This combination produces a molecule with substantial water solubility. Because there are no cysteine, methionine, or tryptophan residues, the peptide lacks the most common oxidation-sensitive side chains, which simplifies handling compared with many longer peptides.
The proposed relationship between epitalon and pineal function is a central part of its background. Khavinson's group reported that short peptides corresponding to regions of larger pineal proteins could influence gene expression in cells. Epitalon was framed as a synthetic analogue of an active fragment rather than a direct isolation product. Whether the tetrapeptide reproduces the effects of the parent extract is an open question, because comparative studies are limited and the parent extract itself is not a single defined substance.
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.
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.
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.
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.
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.
== Professional accomplishments == He designed the first adhesive skin closure tape that could approximate wound edges without the use of sutures. He developed a skin wound cleanser safe enough to be poured into the patient's eye without toxic effects, a solution of poloxamer 188 that has now been approved for use by the Food and Drug Administration (FDA) and is now marketed as Shur-Clens by Convatec (Skillman, New Jersey). He developed the first compact electrosurgical unit.
In selective laser sintering, powdered food materials are heated and bonded together forming a solid structure. This process is completed by bonding the powdered material layer by layer with a laser as the heat source. After a layer is completed with the desired areas bonded, it is then covered by a new unbonded layer of powder. Certain parts of this new unbonded layer are heated by the laser in order to bond it with the structure. This process continues in a vertical upwards manner until the desired food model is constructed. After construction, unbonded material can then be recycled and used to print another food model. Selective laser sintering enables the construction of complex shapes and models and the ability to create different food textures. It is limited by the range of suitable food materials, namely powdered ingredients. Due to this limitation, selective laser sintering has been used primarily for creating sweets/candies.
The formation of GPR43-GPR41 heterodimers has not been evaluated in most studies and may explain otherwise conflicting results on the roles of FFAR3 and FFAR2 in cell function. Furthermore, SC-FAs can alter the function of cells independently of FFAR3 and FFAR2 by altering the activity of cellular histone deacetylases which regulate the transcription of various genes or by altering metabolic pathways which alter cell functions. Given these alternate ways for SC-FAs to activate cells as well as the ability of SC-FAs to activate FFAR2 or, in the case of butyric acid, hydroxycarboxylic acid receptor 2, the studies reported here focus on those showing that the examined action(s) of an SC-FA is absent or reduced in cells, tissues, or animals that have no or reduced FFAR3 activity due respectively to knockout (i.e., removal or inactivation) or knockdown (i.e., reduction) of the FFAR3 protein gene, i.e., the Ffar3 gene in animals or FFAR3 gene in humans.
SPR can be used to study the real-time kinetics of molecular interactions. Determining the affinity between two ligands involves establishing the equilibrium dissociation constant, representing the equilibrium value for the product quotient. This constant can be determined using dynamic SPR parameters, calculated as the dissociation rate divided by the association rate.
Directed by Michael Bate and co-written by Bate and David McDonald, the production was inspired by a March 1973 interview that Bate conducted with Parsons, which became Parsons' last recorded conversation. In 2012, Swedish folk duo First Aid Kit released the single "Emmylou" from the album The Lion's Roar. The song's chorus is a lyrical acknowledgment of the Gram Parsons and Emmylou Harris singing partnership. In the fall of 2012 Florida festival promoter and musician Randy Judy presented his bio-musical Farther Along – The Music and Life of Gram Parsons at Magnoliafest at the Spirit of the Suwannee Music Park. Tribute bands include Cleveland's New Soft Shoe and, out of St. Paul, The Gilded Palace Sinners. In 2022, Dave Prinz, co-founder of Amoeba Music, rediscovered Gram Parsons' "Last Roundup" tapes featuring Emmylou Harris with Gram Parsons and the Fallen Angels. Prinz initiated a campaign to fund the release independently, in partnership with Polly Parsons. The campaign launched on November 17, 2022, and was fully backed. Gram Parsons & The Fallen Angels' "The Last Roundup: Live from The Bijou Café in Philadelphia 3/16/73" was released on limited-edition vinyl on Friday, November 24, 2023, and was considered one of the hits of Record Store Day 2023. In 2021, Zak Bagans and his crew on the hit TV show Ghost Adventures, with a special guest, investigated the Joshua Tree Inn to bring both closure and peace to the Parsons family. In 2026, a restaurant named "Grievous Angel" (named after the Gram Parsons album title) opened in Lakeland, Florida.
Sources: en.wikipedia.org
Hormonal IUDs were developed in the 1970s following the development of the copper IUD in the 1960s and 1970s. Dr. Antonio Scommenga, working at the Michael Reese Hospital in Chicago, discovered that administering progesterone inside the uterus could have contraceptive benefits. With knowledge of Scommegna's work, a Finnish doctor, Jouni Valter Tapani Luukkainen, created the T-shaped IUD that released progesterone, marketed as the Progestasert System in 1976. This IUD had a short, 1-year lifespan and never achieved widespread popularity. Following this relative lack of success, Dr. Luukkainen replaced the progesterone with the hormone levonorgestrel to be released over a five-year period, creating what is now Mirena. The Mirena IUD was studied for safety and efficacy in two clinical trials in Finland and Sweden involving 1,169 women who were all between 18 and 35 years of age at the beginning of the trials. The trials included predominantly Caucasian women who had been previously pregnant with no history of ectopic pregnancy or pelvic inflammatory disease within the previous year. Over 70% of the participants had previously used IUDs. In 2013 Skyla, a lower dose levonorgestrel IUD effective for up to three years, was approved by the FDA. Skyla has a different bleeding pattern than Mirena, with only 6% of women in clinical trials becoming amenorrheic (compared to approximately 20% with Mirena). The city of Turku, Finland, is currently the only production site for the Mirena contraceptive family.
=== Stop-check valve === A stop-check valve is a check valve with override control to stop flow regardless of flow direction or pressure. In addition to closing in response to backflow or insufficient forward pressure (normal check-valve behavior), it can also be deliberately shut by an external mechanism, thereby preventing any flow regardless of forward pressure.
Robert "Bob" Swanson (1947–1999) was an American venture capitalist who co-founded Genentech in 1976 with Herbert Boyer. Genentech is one of the leading biotechnology companies in the world. He was CEO of Genentech from 1976 to 1990, and chairman from 1990 to 1996. Swanson graduated from the Massachusetts Institute of Technology, where he was a member of the Sigma Chi fraternity. He completed a B.S. degree in Chemistry as well as a master's degree in Management from the MIT Sloan School of Management. Both degrees were conferred in 1970. He is regarded as an instrumental figure in launching the biotechnology revolution. The authors of the book, 1,000 Years, 1,000 People: Ranking the Men and Women Who Shaped the Millennium ranked Mr. Swanson number 612. Mr. Swanson was inducted into the Junior Achievement U. S. Business Hall of Fame in 2006. He received the 2000 Biotechnology Heritage Award posthumously with Herbert Boyer. On December 6, 1999, he succumbed to glioblastoma, a type of brain cancer, at the age of 52.
== Further reading == Oh DJ, Chen JL, Vajaranant TS, Dikopf MS (January 2019). "Brimonidine tartrate for the treatment of glaucoma". Expert Opin Pharmacother. 20 (1): 115–122. doi:10.1080/14656566.2018.1544241. PMID 30407890. S2CID 53240954.
Sources: en.wikipedia.org
It is a four-amino-acid peptide built from alanine, glutamate, aspartate and glycine in that order. Its formula is C14H22N4O9, and it is made by chemical synthesis rather than extracted from tissue. The synthetic peptide is a single defined molecule, unlike the pineal extracts it is often compared with.
No. The two spellings refer to the same tetrapeptide, and the difference reflects transliteration from Russian. Laboratories and catalogues use both forms interchangeably. The material is also indexed as AEDG, taken from the one-letter codes of its residues.
Epithalamin is a mixed preparation derived from animal pineal tissue and contains many peptides. Epitalon is one synthetic sequence chosen for study from that broader mixture. Statements about one do not transfer directly to the other.
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.