reversed-phase HPLC is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-03-11. Where a claim depends on a specific study, the study is described rather than over-claimed.
Published work on this compound consists mainly of in vitro experiments, animal studies, and small clinical investigations, a substantial share of which appeared in Russian-language journals. Sample sizes are generally small, control conditions differ between studies, and several endpoints rely on markers whose clinical meaning is itself debated. Reviews of the longevity field treat the peptide as an early example of telomerase-directed research rather than an established intervention. Regulatory treatment varies by country: some jurisdictions place it under prescription controls, others treat it as a laboratory material, and importation may be restricted regardless of local status.
Epitalon is a synthetic tetrapeptide whose sequence is alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. It was developed in Russia during the 1980s and 1990s by investigators associated with the St. Petersburg Institute of Bioregulation and Gerontology, who studied short peptides as regulators of gene expression and tissue function. The alternative spelling epithalon appears interchangeably in the literature, and the two names refer to the same molecule. Outside Russia it is encountered chiefly as a research chemical rather than a licensed medicine, and it holds no approval from the United States Food and Drug Administration or the European Medicines Agency.
The peptide is a synthetic analogue of epithalamin, a preparation extracted from bovine pineal glands. Investigators sought a short, chemically defined molecule that would reproduce some of the endocrine and gerontological observations attributed to the glandular extract. Proposed mechanisms centre on induction of telomerase activity, an effect reported in cultured human somatic cells in the early 2000s, together with influences on melatonin secretion and neuroendocrine regulation. Those mechanisms remain incompletely characterised, and the reported telomerase response has not been consistently reproduced by independent groups working in comparable systems.
Peptides of this size are generally stable as dry solids but degrade in solution over time. The principal routes are hydrolysis of the peptide backbone and oxidation, with hydrolysis favoured by elevated temperature and extreme pH. Aqueous solutions held at room temperature can show measurable loss of purity within days, while frozen aliquots are considerably more durable. Because the sequence contains neither cysteine nor methionine, oxidation is less of a concern than for many other peptides, but pH control during handling still matters.
Typical storage for the lyophilized powder is −20 °C or lower, in a sealed container protected from light and moisture. Hygroscopic material should be allowed to equilibrate to room temperature before the vial is opened, which limits condensation on the contents. Working solutions are commonly divided into single-use aliquots and frozen to avoid repeated freeze-thaw cycles. Dilute solutions are more prone to adsorption onto plastic surfaces and to loss during filtration, so procedures that minimize transfers and use low-binding labware are preferable.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Ala-Glu-Asp-Gly | Often abbreviated AEDG in research literature |
| Common synonyms | Epithalon, epitalon, AEDG | Spelling variants refer to the same tetrapeptide |
| Molecular formula | C14H22N4O9 | Theoretical monoisotopic mass near 390.35 Da |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility class | Freely soluble in water | Hydrophilic peptide; dissolves in aqueous buffer |
The peptide emerged from research carried out in Saint Petersburg from the late 1980s onward, where investigators searched for shorter active fragments of a pineal preparation known as epithalamin. The name epitalon was chosen to reflect that parent extract. Early reports described effects on neuroendocrine markers and on the lifespan of laboratory animals. Much of that work appeared in Russian-language journals, with English translations following later, which affects how readily the original protocols can be assessed by outside groups.
Published studies on epitalon are dominated by a small number of research groups, and independent replication in other laboratories remains limited. Proposed mechanisms include activation of telomerase and modulation of melatonin rhythms, but the evidence for either rests mainly on cell cultures and animal models. Whether the peptide produces comparable effects in humans is an open question, and the absence of large controlled trials means the literature is best read as exploratory rather than settled.
Epitalon is a synthetic four-amino-acid peptide with the sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its molecular formula is C14H22N4O9, and its calculated molar mass is approximately 390.35 grams per mole. The compound is a short fragment related to a peptide fraction isolated from bovine pineal gland extracts, and it is normally supplied as a lyophilised powder intended for laboratory research. It is not a registered pharmaceutical product in most countries.
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.
Identity testing for epitalon relies on reversed-phase high-performance liquid chromatography for purity and mass spectrometry for mass confirmation. Because the sequence contains no tryptophan or tyrosine, ultraviolet detection at 280 nanometres is insensitive, so chromatographic methods usually monitor absorbance near 214 nanometres, where the peptide backbone absorbs. Electrospray ionisation or matrix-assisted laser desorption/ionisation then checks the intact mass against the expected value near 390 daltons. Peptide mapping or amino acid analysis after acid hydrolysis can supplement these measurements, although such confirmatory work is seldom reported on commercial certificates of analysis.
=== Transmission === Once a significant enantiomeric enrichment has been produced in a single biomolecule or biological class of molecules in a system, the transference of chirality through the entire system is possible. This last step is known as the chiral transmission or propagation step. Independently achieving homochirality in every biomolecule (e.g., creating significant enantiomeric enrichment or complete homochirality for all 19 chiral amino acids separately) would be statistically improbable for compounds with different physical and chemical properties and has not yet been experimentally demonstrated. Stereoselective pressure from one biomolecule or biological class to others would eliminate the need to supply all prebiotically-relevant biological precursors in their enantiopure form. Some proposed models for the transmission of chiral asymmetry are polymerization, epimerization or copolymerization. Experimental work has demonstrated that enantiomerically enriched amino acids could assert chiral pressure on sugars and RNA precursors, and vice versa. For example, laboratory experiments demonstrated enantioenrichment of the 3-carbon sugar D-glyceraldehyde from a racemic solution via the interaction of L-proline-valine dipeptide. Furthermore, the stereoselective preference of D-aminoacyl-RNA for L-amino acids in nonenzymatic aminoacylation reactions provide a prebiotically plausible mechanism of chiral information transfer.
Grover CN, Cameron RE, Best SM: Investigating the morphological, mechanical and degradation properties of scaffolds comprising collagen, gelatin and elastin for use in soft tissue engineering. J Mech Behav Biomed Mater. 2012 Jun;10:62-74.
All described specimens of Sinosauropteryx preserve integumentary structures (filaments arising from the skin) which most palaeontologists interpret as a primitive type of feathers. These short, down-like filaments are preserved along the back half of the skull, the arms, neck, back, and top and bottom of the tail. Additional patches of feathers have been identified on the sides of the body, and palaeontologists Chen, Dong and Zheng proposed that the density of the feathers on the back and the randomness of the patches elsewhere on the body indicated the animals would have been fully feathered in life, with the ventral feathers having been removed by decomposition. The filaments are preserved with a gap between the bones, which several authors have noted corresponds closely to the expected amount of skin and muscle tissue that would have been present in life. The feathers are closest to the bone on the skull and end of the tail, where little to no muscle was present, and the gap increases over the back vertebrae, where more musculature would be expected, indicating that the filaments were external to the skin and do not correspond with subcutaneous structures. The filaments exhibit random orientations and are often wavy, which has been interpreted as evidence that they were soft and pliable in life. Microscopic examination shows that individual filaments appear dark along the edges and light internally, suggesting that they were hollow, like modern feathers.
==== Absorption of HMB-Ca ==== After ingestion, HMB-Ca is converted to β-hydroxy β-methylbutyrate following dissociation in the gut. When the HMB-Ca dosage form is ingested, the magnitude and time at which the peak plasma concentration of HMB occurs depends on the dose and concurrent food intake. Higher HMB-Ca doses increase the rate of absorption, resulting in a peak plasma HMB level (Cmax) that is disproportionately greater than expected of a linear dose-response relationship and which occurs sooner relative to lower doses. Consumption of HMB-Ca with sugary substances slows the rate of HMB absorption, resulting in a lower peak plasma HMB level that occurs later.
==== Qualified small business stock gain exclusion ==== The Omnibus Budget Reconciliation Act of 1993 allowed noncorporate taxpayers who acquired qualified small business stock and held the stock for more than five years to exclude from capital gain recognition of up to $10 million or 10 times the taxpayer's basis in the stock, which ever was greater. In order for the stock to qualify, the issuing corporation's aggregate gross assets needed to be no more than $50 million immediately before or after the stock issuance. The OBBBA changed the requirement to hold the stock for at least five years. For qualified small business stock acquired after July 4, 2025, a 50% exclusion is available for stock held at least three years, a 75% exclusion is available for stock held for at least four years, and a 100% continues to be available for stock held for at least five years. The OBBBA also increased the exclusion's limit to $15 million or 10 times the taxpayer's basis in the stock, which ever was greater. The $15-million limit will be subject to annual inflation adjustments in 2027 and thereafter. In addition, the OBBBA now allows the issuing corporation to have an aggregate gross asset limitation of up to $75 million for stock issued after July 4, 2025. The $75-million limit will be subject to annual inflation adjustments in 2027 and thereafter.
Sources: en.wikipedia.org
The English name of "Singapore" is an anglicisation of the native Malay name for the country, Singapura (Malay pronunciation: [siŋapura] ), which was in turn derived from the Sanskrit word for 'lion city' (Sanskrit: सिंहपुर; romanised: Siṃhapura; Brahmi: 𑀲𑀺𑀁𑀳𑀧𑀼𑀭; literally "lion city"; siṃha means 'lion', pura means 'city' or 'fortress'). Pulau Ujong was one of the earliest names for the island of Singapore, which corresponds to a Chinese account from the third century referred to a place as Pú Luó Zhōng (Chinese: 蒲 羅 中), a transcription of the Malay name for 'island at the end of a peninsula'. Early references to the name Temasek (or Tumasik) are found in the Nagarakretagama, a Javanese eulogy written in 1365, and a Vietnamese source from the same time period. The name possibly means Sea Town, being derived from the Malay tasek, meaning 'sea' or 'lake'. The Chinese traveller Wang Dayuan visited a place around 1330 named Danmaxi (Chinese: 淡馬錫; pinyin: Dànmǎxí; Wade–Giles: Tan Ma Hsi) or Tam ma siak, depending on pronunciation; this may be a transcription of Temasek, alternatively, it may be a combination of the Malay Tanah meaning 'land' and Chinese xi meaning 'tin', which was traded on the island. Variations of the name Siṃhapura were used for a number of cities throughout the region prior to the establishment of the Kingdom of Singapura. In Hindu–Buddhist culture, lions were associated with power and protection, which may explain the attraction of such a name.
Pratītya: "having depended". The term appears in the Vedas and Upanishads in the sense of "confirmation, dependence, acknowledge origin". The Sanskrit root of the word is prati* whose forms appear more extensively in the Vedic literature, and it means "to go towards, go back, come back, to approach" with the connotation of "observe, learn, convince oneself of the truth of anything, be certain of, believe, give credence, recognize". In other contexts, a related term pratiti* means "going towards, approaching, insight into anything". Samutpāda: "arising", "rise, production, origin" In Vedic literature, it means "spring up together, arise, come to pass, occur, effect, form, produce, originate". Pratītyasamutpāda has been translated into English as dependent origination, dependent arising, interdependent co-arising, conditioned arising, and conditioned genesis. Jeffrey Hopkins notes that terms synonymous to pratītyasamutpāda are apekṣasamutpāda and prāpyasamutpāda. The term may also refer to the twelve nidānas, Pali: dvādasanidānāni, Sanskrit: dvādaśanidānāni, from dvādaśa ("twelve") + nidānāni (plural of "nidāna", "cause, motivation, link"). Generally speaking, in the Mahayana tradition, pratityasamutpada (Sanskrit) is used to refer to the general principle of interdependent causation, whereas in the Theravada tradition, paticcasamuppāda (Pali) is used to refer to the twelve nidānas.
===== Autophagy ===== HSPs are involved in classical macroautophagy, when protein aggregates are enclosed by double membrane and degraded afterwards. They are also involved in a special type of autophagy called chaperone-mediated autophagy, when they enable cytosolic proteins to get into lysosomes.
On 14 February 2003, the appeals court overturned the verdict, finding that Akre was not a whistleblower because of the Florida "legislature's requirement that agency statements that fit the definition of a "rule" (must) be formally adopted (rules). Recognizing an uncodified agency policy developed through the adjudicative process as the equivalent of a formally adopted rule is not consistent with this policy, and it would expand the scope of conduct that could subject an employer to liability beyond what Florida's Legislature could have contemplated when it enacted the whistle-blower's statute."
Sources: en.wikipedia.org
A mammary gland is an exocrine gland that produces milk in mammals, including humans. Mammals get their name from the Latin word mamma, "breast". The mammary glands are arranged in organs such as the breasts in primates (for example, humans and chimpanzees), the udder in ruminants (for example, cows, goats, sheep, and deer), and the dugs of other animals (for example, dogs, cats, rabbits and pigs) to feed young offspring. Lactorrhea, the occasional production of milk by the glands, can occur in any mammal, but in most mammals, lactation, the production of enough milk for nursing, occurs only in phenotypic females who have gestated in recent months or years. It is directed by hormonal guidance from sex steroids. In a few mammalian species, male lactation can occur. With humans, male lactation can occur only under specific circumstances. Mammals are divided into 3 groups: monotremes, metatherians, and eutherians. In the case of monotremes, their mammary glands are modified sebaceous glands and without nipples. Concerning most metatherians and eutherians, only females have functional mammary glands, with the exception of some bat species. Their mammary glands can be termed as breasts or udders. In the case of breasts, each mammary gland has its own nipple (e.g., human mammary glands). In the case of udders, pairs of mammary glands comprise a single mass, with more than one nipple (or teat) hanging from it.
The cardiovascular effort to recover from each set serves a function similar to an aerobic exercise, but this is not the same as saying that a weight training set is itself an aerobic process. Strength training is typically associated with the production of lactate, which is a limiting factor of exercise performance. Regular endurance exercise leads to adaptations in skeletal muscle which can prevent lactate levels from rising during strength training. This is mediated via activation of PGC-1alpha which alter the LDH (lactate dehydrogenase) isoenzyme complex composition and decreases the activity of the lactate generating enzyme LDHA, while increasing the activity of the lactate metabolizing enzyme LDHB.
=== Autoimmune diseases === Problems posed by the differences in the human and rodent immune systems have been overcome using a few strategies, so as to enable researchers to study autoimmune disorders using humanized models. As a result, the use of humanized mouse models has extended to various areas of immunology and disease research. For instance, humanized mice have been utilized to study human-tropic pathogens, liver cancer models, and the comparison of mouse models to human diseases NSG mice engrafted with PBMCs and administered with myelin antigens in Freund's adjuvant, and antigen-pulsed autologous dendritic cells have been used to study multiple sclerosis. Similarly, NSG mice engrafted with hematopoietic stem cells and administered with pristane have been used for studying lupus erythematosus. Furthermore, NOG mice engrafted with PBMCs has been used to study mechanisms of allografts rejection in vivo. The development of humanized mouse models has significantly advanced the study of autoimmune disorders and various areas of immunology and disease research. These models have provided a platform for investigating human diseases, immune responses, and therapeutic interventions, bridging the gap between human and rodent immune systems and offering valuable insights into disease pathogenesis and potential therapeutic strategies.
==== 1.G Viral fusion pores ==== 1.G.1 The Viral Pore-forming Membrane Fusion Protein-1 (VMFP1) Family 1.G.2 The Viral Pore-forming Membrane Fusion Protein-2 (VMFP2) Family 1.G.3 The Viral Pore-forming Membrane Fusion Protein-3 (VMFP3) Family 1.G.4 The Viral Pore-forming Membrane Fusion Protein-4 (VMFP4) Family 1.G.5 The Viral Pore-forming Membrane Fusion Protein-5 (VMFP5) Family 1.G.6 The Hepadnaviral S Fusion Protein (HBV-S Protein) Family 1.G.7 The Reovirus FAST Fusion Protein (R-FAST) Family 1.G.8 The Arenavirus Fusion Protein (AV-FP) Family 1.G.9 The Syncytin (Syncytin) Family 1.G.10 The Herpes Simplex Virus Membrane Fusion Complex (HSV-MFC) Family 1.G.11 Poxvirus Cell Entry Protein Complex (PEP-C) Family 1.G.12 The Avian Leukosis Virus gp95 Fusion Protein (ALV-gp95) Family 1.G.13 The Orthoreovirus Fusion-associated Small Transmembrane (FAST) Family 1.G.14 The Influenza Virus Hemagglutinin/Fusion Pore-forming Protein (Influenza-H/FPP) Family 1.G.15 The Autographa californica Nuclear Polyhedrosis Virus Major Envelope Glycoprotein GP64 (GP64) Family 1.G.16 The Human Immunodeficiency Virus Type 1 (HIV-1) Fusion Peptide (HIV-FP) Family 1.G.17 The Bovine Leukemia Virus Envelop Glycoprotein (BLV-Env) Family 1.G.18 The SARS-CoV Fusion Peptide in the Spike Glycoprotein Precursor (SARS-FP) Family 1.G.19 The Rotavirus Pore-forming Membrane Fusion Complex (Rotavirus MFC) Family 1.G.20 The Hantavirus Gc Envelope Fusion Glycoprotein (Gc-EFG) Family 1.G.21 The Epstein Barr Virus (Human Herpes Virus 4) Gp42 (Gp42) Family 1.G.22 The Cytomegalovirus (Human Herpesvirus 5) Glycoprotein gO (gO) Family
Manuel Mendonça questioned the coincidences that the court used to come up with the hypothesis that unlinks Mendonça to Alcina Dias, given that, even if it was another child, it would not be normal for them to be accompanied by a man to meet with a prostitute, and that this event had not been investigated. In court, one of the inspectors of the first investigation team, José Ribeiro dos Santos, questioned the testimonies of Carlos Teixeira and Alcina Dias, even being interrupted multiple times so he would not tell testimonies of people that would later appear as witnesses. Ricardo Sá Fernandes said that the use of testimonies of the inspectors to discredit Alcina Dias in court, was illegal. According to lawyer Fernando Arrobas da Silva, the doubts raised in court were the reason a conviction was avoided in the 2012 trial.
Sources: en.wikipedia.org
Epitalon is a synthetic four-amino-acid peptide with the sequence alanine–glutamate–aspartate–glycine, also written AEDG. It was developed in Russian gerontology research and is studied for proposed effects on telomerase, melatonin regulation, and neuroendocrine function. It is not an approved pharmaceutical in the United States or the European Union.
No. Epithalamin is a peptide-rich extract prepared from bovine pineal glands, while epitalon is a short synthetic peptide designed as a defined analogue of it. The synthetic version was intended to provide a reproducible molecule with some of the same proposed biological activity.
Telomere elongation and telomerase activation have been reported in cultured human somatic cells, but evidence from living human subjects is limited and has not been independently confirmed at scale. Reported findings come largely from small studies with differing designs, so the question remains open rather than settled.
The powder is normally kept at −20 °C or below in a sealed, moisture-protected container. Letting the vial reach room temperature before opening helps prevent condensation on the contents.