The short version of reversed-phase HPLC fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-08-08 and is reviewed periodically as new material appears.
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.
Regulatory treatment differs by country. No formulation of epitalon holds a marketing authorisation as a medicine in the United States or the European Union, where material sold for laboratory use is handled as a research chemical and is not intended for human consumption. In Russia, several short peptide preparations from the same institute's peptide series are registered medicinal products, and epitalon appears in that national context. Elsewhere it is frequently offered as a cosmetic ingredient, a category with lighter requirements. Advertising claims about longevity or disease prevention are restricted in most jurisdictions, which limits how sellers describe the compound.
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.
| 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 compound is described in the literature as a derivative of epithalamin, a preparation obtained from bovine pineal tissue. Work on this peptide family was carried out mainly by a research group in Saint Petersburg beginning in the 1980s, and the substance was later registered for clinical use in Russia under the name Epitalon. Outside that region it is generally treated as a research chemical rather than an approved medicine. Statements about its biological activity rest on a relatively small number of studies, and independent replication remains limited.
In its supplied form epitalon is a white to off-white powder, usually lyophilized and often hygroscopic. It dissolves readily in water and in aqueous buffers, and it is commonly handled as the acetate or trifluoroacetate salt to improve stability during purification and drying. The amide backbone is labile in aqueous media, so solutions are less durable than the dry solid. Handling notes in the chemical literature therefore emphasize keeping the powder dry, cool and shielded from light until it is dissolved.
Epitalon is a synthetic tetrapeptide whose sequence is alanine-glutamate-aspartate-glycine, written in single-letter code as AEDG. The four residues are joined by three peptide bonds, giving a linear backbone with no branching and no disulfide bridges. Its calculated molecular mass for the free form is approximately 390.3 daltons, a figure that rises when the compound is supplied as an acetate or trifluoroacetate salt. Because the chain is short, the molecule is defined entirely by its residue order rather than by any folded three-dimensional structure.
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.
Documentation accompanying research peptides usually includes a certificate of analysis listing the batch number, purity figure, and test methods applied. Buyers comparing suppliers should check whether the reported purity refers to chromatographic area or to a mass-balance calculation, because the two are not equivalent. Counter-ion content, residual solvents, and water content are sometimes omitted from such certificates even though they affect the actual peptide mass present. Independent verification through a second laboratory is the most direct way to confirm that a supplied material matches its label.
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.
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.
== Contraindications == Benzodiazepines require special precaution if used in children and in alcohol- or other drug-dependent individuals. Particular care should be taken in pregnant or elderly people, people with substance use disorder history, particularly alcohol dependence, and people with comorbid psychiatric disorders. Alprazolam should be avoided or carefully monitored by medical professionals in individuals with myasthenia gravis, acute narrow-angle glaucoma, severe liver deficiencies such as cirrhosis, severe sleep apnea, pre-existing respiratory depression, marked neuromuscular respiratory, acute pulmonary insufficiency, chronic psychosis, hypersensitivity, allergy to alprazolam or other benzodiazepines, and borderline personality disorder, where it may induce suicidality and dyscontrol. Like all central nervous system depressants, alprazolam in larger-than-normal doses can cause significant deterioration in alertness and increase drowsiness, especially in those unaccustomed to the drug's effects.
== Chemistry == Succimer is an isomer of 2,3-dimercaptosuccinic acid. 2,3-dimercaptosuccinic acid is the organosulfur compound with the formula HO2CCH(SH)CH(SH)CO2H. This colorless solid contains two carboxylic acid and two thiol groups, the latter being responsible for its mildly unpleasant odour. It occurs in two diastereomers, meso and the chiral dl forms. The 2,3-dimercaptosuccinic acid molecule has two stereocentres (two asymmetric carbon atoms), and can exist as three different stereoisomers. The 2S,3S and 2R,3R isomers are a pair of enantiomers, whereas the 2R,3S isomer (succimer) is a meso compound and thus optically inactive.
1994: Ong Yeow Tian, a Singaporean hairstylist who was hanged on 25 November 1994 for murdering a police officer and shooting two other cops in 1989. 1995: Ng Theng Shuang, a Malaysian national, hanged on 14 July 1995 for discharging a firearm with intent to cause injury, after shooting 3 people during the attempted robbery of Tin Sing Goldsmiths in South Bridge Road in 1992. 1997: Lim Chwee Soon, hanged on 25 July 1997 for discharging a firearm seven times during the robbery of the Kee Hing Hung Rolex boutique at the People's Park Complex in 1995. 2001: Tay Chin Wah, a Singaporean taxi driver, was arrested for an unsolved 1995 case of shooting two men. He was sentenced to death on 21 February 2001, and hanged on 26 October 2001. 2006: Khor Kok Soon, one of Singapore's top ten fugitives, was charged in 2004 for firing a gun at 43-year-old police sergeant Lim Kiah Chin (who escaped unharmed) in 1984. He was sentenced to death in February 2005, and eventually hanged. Khor was also alleged to have killed 25-year-old truck driver Ong King Hock. 2006: Lim Thian Lai, a Singaporean gunman who was caught in 2004 for murdering an illegal moneylender Tan Tiong Huat back in 1997. Lim was found guilty of discharging a firearm and killing Tan by shooting, and sentenced to death in May 2005. He lost his appeal in September 2005 and had since been hanged. 2009: Tan Chor Jin, alias Tony Kia, nicknamed the "One-eyed Dragon" in Singapore media, was executed on 9 January 2009 for illegally discharging a firearm and killing 41-year-old nightclub owner Lim Hock Soon by shooting.
=== Classification === A clinical severity score has been developed to assess chronic venous ulcers. It is based on the CEAP (clinical, etiology, anatomy, and pathophysiology) classification system developed by an expert panel. A high score gives a poor prognosis.
== NPHCDA tenure == Muhammad worked to achieve seven major objectives at the NPHCDA. The objectives were: To control preventable diseases; Improve access to basic health services; Improve quality of care; Strengthen institutions in the healthcare system; Develop a high-performing and empowered health workforce across the country. Other goals are to strengthen partnerships and engage with communities regularly to get feedback.
Sources: en.wikipedia.org
==== China ==== On May 12, the United States and China announced that tariffs would be reduced for a period of 90 days. U.S. tariffs on Chinese goods would be reduced from 145% to 30% and Chinese tariffs on U.S. goods would be reduced from 125% to 10%. However, this 30% is still more expensive for consumers in the United States compared to the state of affairs before Trump's initial tariffs. On August 11, 2025, this deal was extended for another 90 days.
Philip Hampton, at that time chair of the Royal Bank of Scotland, became GSK chairman in September 2015. On 31 March 2017, Emma Walmsley became CEO. She is the first female CEO of the company. In December 2017, Reuters reported that Glaxo had increased its stake in its Saudi Arabian unit to 75% (from 49%) taking over control from its Saudi partner Banaja KSA Holding Company. With respect to rare diseases, the company divested its portfolio of gene therapy drugs to Orchard Therapeutics in April 2018. In November 2018, Reuters reported that Unilever was in prime position to acquire GSK's interest in its Indian unit, GlaxoSmithKline Consumer Healthcare Ltd, in a sale that could generate around US$4 billion for the company. Nestlé and Coca-Cola have also been reported to be interested in the business unit as they look to strengthen their presence in India. On 3 December 2018, GSK announced that Unilever would acquire the Indian-listed GlaxoSmithKline Consumer Healthcare business for US$3.8 billion (£2.98 billion). Unilever will pay the majority of the deal in cash, with the remaining being paid in shares in its Indian operation, Hindustan Unilever Limited. Upon completion, GSK will then own around 5.7% of Hindustan Unilever Limited, selling those shares in a number of tranches. The same day, the company also announced it would acquire oncology specialist, Tesaro, for US$5.1 billion. The deal will give GSK control of ovarian cancer treatment, Zejula - a member of the class of poly ADP ribose polymerase (PARP) inhibitors.
Secondary ion mass spectrometry (SIMS) is used to analyze the composition of solid surfaces and thin films by sputtering the surface of the specimen with a focused primary ion beam and collecting and analyzing ejected secondary ions. The mass/charge ratios of these secondary ions are measured with a mass spectrometer to determine the elemental, isotopic, or molecular composition of the surface to a depth of 1 to 2 nm. In a liquid metal ion source (LMIS), a metal (typically gallium) is heated to the liquid state and provided at the end of a capillary or a needle. Then a Taylor cone is formed under the application of a strong electric field. As the cone's tip get sharper, the electric field becomes stronger, until ions are produced by field evaporation. These ion sources are particularly used in ion implantation or in focused ion beam instruments.
Commission A2: Liquefaction and Separation of Gases The work of "Commission A2: Liquefaction and Separation of Gases" reflects worldwide activities in the domain of separation of gases and liquefaction. Apart from the personal involvement of Commission members in various projects, the commission is present at conferences, workshops and seminars: LNG International Exhibition and Conference, GASTECH, Cryogenics, Cryogen Expos, European Cryogenic Course and others. The commission is close to academia, industry and end users of separated and liquefied gases. Commission members work closely with Commission A1 Cryophysics, Cryoengineering and Commission C1 Cryobiology, Cryomedicine and Health Products.
Sources: en.wikipedia.org
== Applications == Sericin has also been used in medicine and cosmetics. Due to its elasticity and tensile strength, along with a natural affinity for keratin, sericin is primarily used in medicine for wound suturing. It also has a natural infection resistance, and is used variably due to excellent biocompatibility, and thus is used commonly as a wound coagulant as well. When used in cosmetics, sericin has been found to improve skin elasticity and several anti-aging factors, including an anti-wrinkle property. This is done by minimizing water loss from the skin. To determine this, scientists ran several experimental procedures, including a hydroxyproline assay, impedance measurements, water loss from the epidermis and scanning electron microscopy to analyze the rigidity and dryness of the skin. The presence of sericin increases hydroxyproline in the stratum corneum, which in turn, decreases skin impedance, thus increasing skin moisture. Adding in pluronic and carbopol, two other ingredients that can be included in sericin gels, performs the action of repairing natural moisture factors (NMF), along with minimizing water loss and in turn, improving skin moisture.
=== Combined with statins === Extended release nicotinic acid was combined with lovastatin (Advicor), and with simvastatin (Simcor), as prescription drug combinations. The combination niacin/lovastatin was approved by the US Food and Drug Administration (FDA) in 2001. The combination niacin/simvastatin was approved by the FDA in 2008. Subsequently, large outcome trials using these nicotinic acid and statin therapies were unable to demonstrate incremental benefit of nicotinic acid beyond statin therapy alone. The FDA withdrew approval of both drugs in 2016. The reason given: "Based on the collective evidence from several large cardiovascular outcome trials, the Agency has concluded that the totality of the scientific evidence no longer supports the conclusion that a drug-induced reduction in triglyceride levels and/or increase in HDL-cholesterol levels in statin-treated patients results in a reduction in the risk of cardiovascular events." The drug company discontinued the drugs.
Agarose gel matrix is often used for protein purification, for example, in column-based preparative scale separation as in gel filtration chromatography, affinity chromatography and ion exchange chromatography. It is however not used as a continuous gel, rather it is formed into porous beads or resins of varying fineness. The beads are highly porous so that protein may flow freely through the beads. These agarose-based beads are generally soft and easily crushed, so they should be used under gravity-flow, low-speed centrifugation, or low-pressure procedures. The strength of the resins can be improved by increased cross-linking and chemical hardening of the agarose resins, however such changes may also result in a lower binding capacity for protein in some separation procedures such as affinity chromatography. Agarose is a useful material for chromatography because it does not absorb biomolecules to any significant extent, has good flow properties, and can tolerate extremes of pH and ionic strength as well as high concentration of denaturants such as 8M urea or 6M guanidine HCl. Examples of agarose-based matrix for gel filtration chromatography are Sepharose and WorkBeads 40 SEC (cross-linked beaded agarose), Praesto and Superose (highly cross-linked beaded agaroses), and Superdex (dextran covalently linked to agarose). For affinity chromatography, beaded agarose is the most commonly used matrix resin for the attachment of the ligands that bind protein. The ligands are linked covalently through a spacer to activated hydroxyl groups of agarose bead polymer.
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 solid is kept cold, dry and dark, typically at minus twenty degrees Celsius, in a sealed container with desiccant. Dissolved material is kept refrigerated and used promptly. Freezing and thawing a solution repeatedly is avoided because it accelerates degradation.