aspartimide raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-12-13. Anything still debated is marked as such rather than presented as settled.
Stability of the tetrapeptide follows ordinary peptide chemistry rather than any unusual structural feature. The aspartate-glycine pair is prone to aspartimide formation under mildly basic or neutral conditions, and deamidation can follow, altering both mass and chromatographic retention. Dry lyophilised powder kept at or below minus twenty degrees Celsius is the usual handling recommendation, with repeated freeze-thaw cycles avoided. Once dissolved in neutral aqueous buffer, degradation proceeds over days to weeks depending on pH and temperature, while acidic conditions generally slow the aspartimide route. A formal stability-indicating study has not been published in the indexed literature.
Because epitalon has no pharmacopoeial monograph, quality assessment depends on supplier documentation and independent testing. Certificates of analysis typically report a purity figure from a single chromatographic run, a measured mass and sometimes an appearance description, but methods and acceptance criteria are not harmonised across vendors. Third-party laboratories can repeat identity and purity measurements, and mismatches between labelled and measured peptide content have been described for research peptides generally. What constitutes adequate identity confirmation for a molecule of this size stays an open question, since mass agreement alone does not separate closely related sequences.
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.
| Property | Value | Notes |
|---|---|---|
| Analytical method | Reversed-phase HPLC | Purity determination, typically 214 nm |
| Mass confirmation | ESI or MALDI mass spectrometry | Compared with mass near 390 Da |
| Common synonyms | Epitalon, epithalon, AEDG | Naming differs between suppliers |
| Storage temperature | −20 °C or lower | Lyophilised powder, kept desiccated |
| Solution stability | Limited in neutral aqueous buffer | Aspartimide and hydrolysis pathways |
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.
Verification of a sample usually begins with reversed-phase high-performance liquid chromatography, which resolves the peptide from truncated sequences and other impurities and expresses purity as a percentage of total peak area. Mass spectrometry by electrospray ionisation or matrix-assisted laser desorption supplies an independent check, because the measured mass can be compared against the theoretical value for AEDG. Amino acid analysis or tandem mass spectrometry sequencing can confirm residue order. Each of these methods answers a different question: a purity figure does not establish identity, and an identity match does not establish how much of the material is intact peptide.
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.
== External links == Clinical trial number (NCT05656027 for "Phase 3 Evaluation of the Safety and Efficacy of LNZ101 for the Treatment of Presbyopia (CLARITY)" at ClinicalTrials.gov Clinical trial number (NCT05728944 for "Phase 3 Efficacy Study of LNZ101 for the Treatment of Presbyopia (CLARITY)" at ClinicalTrials.gov Clinical trial number (NCT05753189 for "Phase 3 Safety Study for the Treatment of Presbyopia Subjects" at ClinicalTrials.gov
The AToFMS allows for the determination of mixing state, or distribution of chemical species, within individual particles. These mixing states are important in the determination of climate and health impact of aerosols. The schematic of a typical AToFMS is shown to the right. The overall structure of ATOF instruments is; sampling, sizing, and the mass analyzer region. The inlet system is similar to the AMS by using the same aerodynamic focusing lens, but it has smaller orifices because of its analysis of single particles. In the sizing region particle passes through the first continuous solid state laser that generates an initial pulse of scattered light. Then the particle passes through the second laser that is orthogonal to the first and produces a pulse of scattered light. The light is detected by a photomultiplier (PMT) that is matched up to each laser. Using the transit times between the two detected pulses and the fixed distance the velocity and size of each particle is calculated. Next the particles travel through to the mass analyzer region where it is ionized by a pulsed LDI laser, which is timed to hit the particle as it reaches the center of the ion extraction region. Once ionized, the positive ions are accelerated towards the positive ToF section and the negative ions are accelerated towards the negative ToF section where they are detected.
Pituitary prolactin is controlled by the Pit-1 transcription factor, which binds to the gene at several sites including a proximal promoter. This promoter is inhibited by dopamine and stimulated by estrogens, neuropeptides, and growth factors. Estrogens can also suppress dopamine. Interaction with neuropeptides is still a matter of active research: no specific prolactin-releasing hormone has been identified. It is known that mice react to both VIP and TRH, but humans seem to only react to TRH. There are prolactin-releasing peptides that work in vitro, but whether they deserve their name has been questioned. Oxytocin does not play a large role. Mice without a posterior pituitary do not raise their prolactin levels even with suckling and oxytocin injection, but scientists have yet to identify which specific hormone produced by this region is responsible. In birds (turkeys), VIP is a powerful prolactin-releasing factor, while peptide histidine isoleucine has almost no effect.
The final step in the non-mevalonate pathway is carried out by the enzyme 4-hydroxy-3-methylbut-2-enyl diphosphate reductase, which gives a mixture of dimethylallyl pyrophosphate and isopentenyl pyrophosphate in the ratio of five to one. The products are then used in terpenoid biosynthesis. HMB-PP is an essential metabolite in most pathogenic bacteria including Mycobacterium tuberculosis as well as in malaria parasites, but is absent from the human host. HMB-PP is the physiological activator ("phosphoantigen") for human Vγ9/Vδ2 T cells, the major γδ T cell population in peripheral blood. With a bioactivity of 0.1 nM it is 10,000-10,000,000 times more potent than any other natural compound, such as IPP or alkyl amines. HMB-PP functions in this capacity by binding the B30.2 domain of BTN3A1. 4-hydroxy-3-methylbut-2-enyl+pyrophosphate at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
CCL7 is expressed in many types of cells, including stromal cells, keratinocytes, airway smooth muscle cells, parenchymal cells, fibroblasts and leukocytes and also in tumor cells. CCL7 mainly acts as a chemoattractant for several leukocytes, including monocytes, eosinophils, basophils, dendritic cells (DCs), neutrophils, NK cells and activated T lymphocytes. Thus, chemotactic factor CCL7 recruits leukocytes to infected tissues to mediate the immune response. Furthermore, CCL7 has an influence to diapedesis and extravasation of leukocytes. The positive effect of CCL7 is mainly observed in monocyte mobilization from bone marrow to blood circulation and in the recruitment of monocytes to sites of inflammation. It was also reported, that CCL7 can also induce neutrophil migration to the inflammatory site by increasing intracellular Ca2+ flux, which is more typical for the CXC chemokine family members. The speed of immune responses varies depending on the type of the cells. In epithelial cells, fibroblasts, and endothelial cells the response is immediate after the stimulation by proinflammatory cytokines as IL-1β and TNFα. In T lymphocytes the expression of CCL7 occurs after 3–5 days after the stimulation. CCL7 has been shown to interact with MMP2 by binding CCR2 receptor.
Sources: en.wikipedia.org
== Silicon-34 == Silicon-34 is a radioactive isotope with a half-life of 2.8 seconds. In addition to the usual N = 20 closed shell, the nucleus also shows a strong Z = 14 shell closure, making it behave like a doubly magic spherical nucleus, except that it is also located two protons above an island of inversion. Silicon-34 has an unusual "bubble" structure where the proton distribution is less dense at the center than near the surface, as the 2s1/2 proton orbital is almost unoccupied in the ground state, unlike in 36S where it is almost full. Silicon-34 is one of the known cluster decay emission particles; it is produced in the decay of 242Cm with a branching ratio of approximately 1×10−16.
Insulin is usually given subcutaneously, either by injections or by an insulin pump. In acute care settings, insulin may also be given intravenously. Insulins are typically characterized by the rate at which they are metabolized by the body, yielding different peak times and durations of action. Faster-acting insulins peak quickly and are subsequently metabolized, while longer-acting insulins tend to have extended peak times and remain active in the body for more significant periods. Examples of rapid-acting insulins (peak at ~1 hour) are:
===== Serpentes (Snakes) ===== Clade Scolecophidia (Blindsnakes) Family Typhlopidae Anilios bituberculatus, Prong-snouted blind snake (2021) Indotyphlops braminus, Brahminy blindsnake, (2022) Clade Booidea Family Pythonidae Morelia viridis, Green Tree Python (2022) Python bivittatus, Burmese python (2013) Python regius, Ball python (2020) Simalia boeleni, Boelen's Python (2022) Family Boidae Boa constrictor, Boa constrictor (2019) Charina bottae, Rubber boa, (2022) Clade Caenophidia Family Viperidae Azemiops feae, Fea's viper (2022) Bothrops jararaca, Jararaca lancehead, (2021) Crotalus adamanteus, Eastern diamondback rattlesnake (2021) Crotalus mitchellii pyrrhus, southwestern speckled rattlesnake (2014) Crotalus oreganus helleri, southern Pacific rattlesnake (2023) Crotalus tigris, Tiger rattlesnake (2021) Crotalus viridis, Great Plains rattlesnake (2018) Daboia siamensis, Eastern Russell's viper (2022) Deinagkistrodon acutus, Five-pacer viper (2016) Protobothrops flavoviridis, Okinawa Habu (2018) Protobothrops mucrosquamatus, Taiwanese Habu (2017, 2024) Trimeresurus albolabris, White-lipped tree pit viper (2024) Cerastes gasperetti, Arabian horned viper (2025) Family Homalopsidae Myanophis thanlyinesis, (No common name), (2021) Family Colubridae Ahaetulla prasina, Asian vine snake (2023) Arizona elegans occidentalis, California glossy snake (2022) Chrysopelea ornata, Ornate Flying Snake (2023) Diadophis punctatus, ring-necked snake (2023) Dolichophis caspius, Caspian whipsnake (2020) Elaphe carinata, King ratsnake (2024) Pantherophis guttatus, corn snake (2014) Pantherophis obsoletus, Leucistic Texas Rat Snake (2021) Ptyas mucosa, Oriental rat snake (2024) Thamnophis sirtalis, Common garter snake (2018) Thermophis baileyi, Tibetan hot-spring snake (2018) Family Elapidae Bungarus multicinctus, Many-banded krait (2022) Emydocephalus ijimae, Ijima's turtle-headed sea snake, (2019) Hydrophis curtus, Shaw's Sea Snake (2020) Hydrophis cyanocinctus, blue-banded sea snakes (2021) Hydrophis melanocephalus, slender-necked sea snake, (2019) Laticauda colubrina, yellow-lipped sea krait, (2019) Laticauda laticaudata, blue-lipped sea krait, (2019) Naja atra, Chinese cobra (2024) Naja naja, Indian cobra (2020) Notechis scutatus, mainland tiger snake (2022) Ophiophagus hannah, king cobra (2013) Pseudonaja textilis, eastern brown snake (2022)
=== Infectious factors === Nursing mothers diagnosed with yeast, bacterial, viral infections or dermatitis are susceptible to nipple pain. A type of yeast infection called candidiasis caused by a type of fungus called Candida will lead to itching, erythema of the nipple and areola, burning and stabbing nipple pain. It happens when the infant's mouth is infected by a Candida species called Candida albicans, the child may transmit the yeast to the mother's nipple during breastfeeding. Bacterial infection by Staphylococcus aureus (S.aureus) will give rise to mastitis which refers to an inflammation of the mammary gland. About half of the breastfeeding mothers reporting nipple ache were infected with S.aureus. They usually experienced a sudden onset and systemic symptoms including nipple pain, fever, flu-like symptoms, myalgia and fatigue. The risk of infections increases with an inhibition of mammary gland drainage. Viral infection with Herpes simplex virus (HSV) causes nipple ulceration, soreness and pain. Infants feeding on an HSV infected nipple can develop a life-threatening complication affecting the brain called encephalitis. Breastfeeding women with dermatitis problems, including psoriasis and eczema at the nipple, suffer from erythema, scaling lesion and pain. Nursing mothers with psoriasis may develop Koebner phenomenon upon further nipple abrasion by infants in prolonged breastfeeding. Eczema at the nipple can be caused by direct chemical contact or allergic condition. It affects the areola and sometimes extends to the breast.
After the deaths of three successive elderly Soviet leaders since 1982, the Soviet Politburo elected Gorbachev Communist Party General Secretary in March 1985, marking the rise of a new generation of leadership. Under Gorbachev, relatively young reform-oriented technocrats, who had begun their careers in the heyday of "de-Stalinization" under reformist leader Nikita Khrushchev, rapidly consolidated power, providing new momentum for political and economic liberalization, and the impetus for cultivating warmer relations via glasnost and trade with the West. Historian Sheila Fitzpatrick wrote that Gorbachev looked on these reforms "through the prism of the Thaw, as a revitalization of socialism rather than an abandonment of it."
Sources: en.wikipedia.org
The molecule lacks aromatic residues, so it absorbs weakly near 280 nanometres, the wavelength applied to many other peptides. The peptide bond absorbs strongly below 220 nanometres, making 214 nanometres a practical compromise. Gradient methods must therefore use mobile phases with low ultraviolet absorbance to keep the baseline clean.
Neutral and slightly basic aqueous conditions promote aspartimide formation at the aspartate-glycine step, often followed by deamidation. Elevated temperature and repeated freeze-thaw cycles accelerate the loss. Acidic solutions and dry lyophilised powder are comparatively stable over short periods.
No monograph exists in the United States Pharmacopeia or the European Pharmacopoeia, and no widely distributed certified reference standard is available. Purity and identity therefore rest on supplier methods that are not harmonised. This absence is the main reason reported purities are difficult to compare between sources.
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.