If you have been reading about lyophilized powder 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 2025-07-27. Numbers and descriptions here follow the published literature rather than marketing material.
Stability depends strongly on pH, temperature and the presence of oxygen and trace metals. Cleavage of the backbone proceeds faster under neutral to alkaline conditions, whereas acidic solutions tend to slow that reaction. The aspartate and glutamate side chains can undergo deamidation or imide formation over time, generating closely related impurities. Published stability data specific to epitalon are sparse, so the usable life of a given solution is best regarded as an open question that depends on buffer composition, concentration and storage temperature.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography with ultraviolet detection, frequently near 214 nanometers where the peptide bond absorbs. Mass spectrometry, most often with electrospray ionization, confirms the observed molecular mass and helps separate the intact peptide from truncated or modified forms. Amino acid analysis or tandem mass spectrometry can establish residue order. Purity is commonly quoted as an area percentage, yet such values are method-dependent, and comparisons between laboratories require matching column, gradient and detection wavelength.
Laboratory handling begins with dissolution of the lyophilized powder in water or a suitable aqueous buffer. The dry solid is the more stable form, so stock solutions are generally prepared only when required and kept cold afterwards. Repeated freezing and thawing of a solution is avoided because it encourages aggregation and gradual loss of the intact chain. Diluents and containers are selected to limit adsorption of a short peptide onto plastic surfaces and to reduce microbial growth in aqueous preparations.
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.
| Property | Value | Notes |
|---|---|---|
| Storage temperature, dry powder | -20 degrees Celsius or lower | Sealed, dark, low humidity |
| Storage temperature, solution | 2 to 8 degrees Celsius | Short-term use expected |
| Primary purity method | Reversed-phase HPLC | Ultraviolet detection near 214 nm |
| Identity confirmation | Electrospray mass spectrometry | Compared with calculated mass |
| Typical purity specification | Area percent of 95 or higher | Depends on column and gradient |
Purity assessment of peptide reagents normally relies on reversed-phase high-performance liquid chromatography. A gradient of acetonitrile in water with trifluoroacetic acid, paired with a C18 stationary phase, separates the target tetrapeptide from truncated sequences and deletion analogues. Detection at 214 nanometres exploits absorbance of the peptide backbone, since the molecule contains no aromatic residue. Results are expressed as a percentage of total peak area. Values above ninety-five percent are typical for research-grade material, although reporting conventions vary between suppliers.
Identity confirmation uses mass spectrometry, usually electrospray ionisation in positive mode or matrix-assisted laser desorption. The protonated free peptide produces a signal near three hundred and ninety-one daltons, while salt adducts shift that value slightly. Tandem mass spectrometry or amino acid analysis supplies sequence-level confirmation, which a single mass measurement cannot. Peptides containing aspartate can cyclise into succinimide intermediates that hydrolyse to isoaspartate isomers of identical mass. Because those isomers are difficult to separate chromatographically, identity and purity results carry more weight when interpreted together.
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.
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.
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 and handling follow conventional peptide practice. Lyophilized epitalon is typically kept refrigerated or frozen, protected from moisture and light, and allowed to equilibrate to room temperature before opening to avoid condensation. Once dissolved, aqueous solutions are usually stored cold and used within a short period, since dilute peptide solutions can support microbial growth and may slowly degrade. The absence of cysteine and methionine reduces, but does not eliminate, oxidation concerns during long-term storage.
Regulatory status varies by country and is not harmonized. Epitalon is not an approved drug in major Western jurisdictions. In some countries it is sold as a research chemical, and in others it has appeared in products marketed for other categories. This inconsistent status means that purity, labeling accuracy, and documentation differ widely between suppliers, and verification of identity and purity through independent analysis is the usual way buyers assess a given lot.
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.
== Relationship to other stewardship approaches == Laboratory stewardship, diagnostic stewardship, and antimicrobial stewardship address related but distinct aspects of healthcare. Laboratory stewardship focuses on the appropriate use of clinical laboratory services, including the ordering, retrieval, and interpretation of laboratory tests. Diagnostic stewardship focuses on the appropriate use of diagnostic testing throughout the diagnostic process, including test ordering, specimen collection and processing, testing, and reporting and interpretation of results. Antimicrobial stewardship focuses on the appropriate use of antimicrobial medicines, including the selection, dosing, route, and duration of treatment.
== Use == A common way to synthesize an NHS-activated acid is to mix NHS with the desired carboxylic acid and a small amount of an organic base in an anhydrous solvent. A coupling reagent such as dicyclohexylcarbodiimide (DCC) or 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) is then added to form a highly reactive activated acid intermediate. NHS reacts to create a less labile activated acid. The group is usually written as SuO- or -OSu in chemical notation. Such an ester with acid and NHS, sometimes called succinate ester, is stable enough to be purified and stored at low temperatures in the absence of water and, as such, is commercially available. NHS esters are commonly used for protein modification (e.g. an NHS ester of fluorescein is commercially available, and can be added to a protein to obtain a fluorescently labeled protein in a straightforward reaction and purification step). NHS can be used with EDC to immobilize enzymes for biosensor applications.
=== Symptoms === Symptoms of SNRI overdose, whether it be a mixed drug interaction or the drug alone, vary in intensity and incidence based on the amount of medicine taken and the individuals sensitivity to SNRI treatment. Possible symptoms may include:
Sources: en.wikipedia.org
== Toxicity == Since 2016, G. biloba extract is classified as a possible human carcinogen (group 2B) by the International Agency for Research on Cancer. When eaten in large quantities or over a long period, the seeds may cause poisoning by ginkgotoxin (4'-O-methylpyridoxine, MPN), as found in a few case reports. A heat-stable compound not destroyed by cooking, MPN may cause convulsions, which were alleviated by treatment with pyridoxine phosphate (vitamin B6), according to limited studies. Some people are sensitive to the chemicals in the sarcotesta, the outer fleshy coating. These people should handle the seeds with care, wearing disposable gloves, when preparing them for consumption. The symptoms are allergic contact dermatitis, or blisters similar to that caused by contact with poison ivy. Side effects of using ginkgo supplements may include increased risk of bleeding, gastrointestinal discomfort, nausea, vomiting, diarrhea, headaches, dizziness, heart palpitations, and restlessness. Although use of standardized Ginkgo biloba leaf extracts in moderate amounts appears to be safe, excessive use may have undesirable effects, especially in terms of drug interactions. The dosing of anticoagulants, such as warfarin or antiplatelet medication, may be adversely affected by using ginkgo supplements. According to a systematic review, the effects of ginkgo on pregnant women may include increased bleeding time, and there is inadequate information about safety during lactation. Ginkgo pollen may produce allergic reactions. G.
Corticosteroids such as prednisolone, deflazacort, and vamorolone (Agamree) lead to short-term improvements in muscle strength and function up to 2 years. Corticosteroids have also been reported to help prolong walking, though the evidence for this is not robust. Disease-specific physical therapy helps maintain muscle strength, flexibility, and function. It aims to: Minimize the development of contractures and deformity by developing a program of stretches and exercises where appropriate Anticipate and minimize other secondary complications of physical nature by recommending bracing and durable medical equipment Monitor respiratory function and advise on techniques to assist with breathing exercises and methods of clearing secretions Orthopedic appliances (such as braces and wheelchairs) may improve mobility and the ability for self-care. Form-fitting removable leg braces that hold the ankle in place during sleep can defer the onset of contractures. Appropriate respiratory support as the disease progresses is important. Cardiac problems may require a pacemaker. The medication eteplirsen, a Morpholino antisense oligo, has been approved in the United States for the treatment of mutations amenable to dystrophin exon 51 skipping. The US approval has been controversial as eteplirsen failed to establish a clinical benefit; it has been refused approval by the European Medicines Agency. The medication ataluren (Translarna) is approved for use in the European Union.
==== 900–999 ==== Act of Sederunt (Rules of the Court of Session Amendment No. 2) (Fees of Solicitors) 1993 (S.I. 1993/900) Further Education (Exclusion of Land from Transfer) Order 1993 (S.I. 1993/901) Greater Manchester and Lancashire (County and Metropolitan Borough Boundaries) Order 1993 (S.I. 1993/902) Dyfed-Powys Police (Amalgamation) (Amendment) Order 1993 (S.I. 1993/909) National Rivers Authority (Anglian Region) (Reconstitution of the Witham Third District Internal Drainage Board) Order 1993 (S.I. 1993/910) Plymouth Development Corporation (Area and Constitution) Order 1993 (S.I. 1993/911) Electricity (Restrictive Trade Practices Act 1976) (Exemption) Order 1993 (S.I. 1993/912) Child Support (Miscellaneous Amendments) Regulations 1993 (S.I. 1993/913) Act of Sederunt (Child Support Act 1991) (Amendment of Ordinary Cause and Summary Cause Rules) 1993 (S.I. 1993/919) Act of Sederunt (Child Support Rules) 1993 (S.I. 1993/920) Act of Sederunt (Bankruptcy Rules) 1993 (S.I. 1993/921) Land Registration (Scotland) Act 1979 (Commencement No. 7) Order 1993 (S.I. 1993/922) Dairy Produce Quotas Regulations 1993 (S.I. 1993/923) Education (Dissolution of the Council for National Academic Awards) Order 1993 (S.I. 1993/924) Child Support (Maintenance Assessments and Special Cases) Amendment Regulations 1993 (S.I. 1993/925) Greater Manchester and Lancashire (County and District Boundaries) Order 1993 (S.I. 1993/926) Secure Tenancies (Designated Courses) (Amendment) Regulations 1993 (S.I.
== Regulation of prolactin secretion == Because lactotrophs are constitutively active, prolactin secretion operates through a "release from inhibition" model. Several inhibitory and stimulatory factors modulate the system.
Sources: en.wikipedia.org
The dry powder is typically held at -20 degrees Celsius or lower, protected from light and moisture. Allowing a sealed vial to reach room temperature before opening reduces condensation on its contents. Conditions stated on a supplier certificate of analysis take precedence over general guidance.
Mass spectrometry supplies an observed molecular mass that is compared with the calculated value for the tetrapeptide. Reversed-phase chromatography then separates the main peak from related impurities. Neither technique alone establishes residue order, so sequence-level confirmation may call for tandem mass spectrometry or amino acid analysis.
No single published figure applies, because stability depends on pH, concentration, temperature and sterility. Cold storage slows hydrolysis without halting it, and microbial growth is a separate concern in non-sterile solutions. Most laboratories rely on their own analytical checks rather than a fixed expiry period.
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.