Reversed-phase HPLC 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 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
The molecule is a short, linear, hydrophilic peptide that dissolves readily in water or aqueous buffer. Its principal chemical liabilities are hydrolytic rather than oxidative, since it contains no cysteine, methionine, or tryptophan residues. The aspartate–glycine step is a recognised site for aspartimide formation under mildly acidic or basic conditions, generating isoaspartate and succinimide-related products over time. Desiccated lyophilised powder held at −20 °C is comparatively stable, whereas dilute solutions degrade faster and are best frozen as single-use aliquots rather than thawed repeatedly.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Identity confirmation | Electrospray or MALDI mass spectrometry | Observed mass compared with theoretical 390.35 Da |
| Purity specification | 95 percent or greater by RP-HPLC | Common convention for research-grade peptide |
| Counter-ion | Acetate or trifluoroacetate | Affects net peptide content of a weighed sample |
| Solution storage | −80 °C as single-use aliquots | Repeated freeze–thaw cycles accelerate loss |
| Main degradation route | Aspartimide formation at Asp-Gly | Produces isoaspartate and related species |
Animal and clinical reports appear mainly in Russian-language journals from the 1990s and 2000s, covering endpoints such as melatonin rhythm, lifespan in aged rodents, and retinal function. Many of these papers involve small groups, lack blinding or placebo comparison, and are difficult to retrieve through indexed databases. Review articles published in English generally summarise the claims without reanalysing the underlying data. Because no large randomised trial exists, the clinical importance of these reported effects stays unresolved and is properly described as an open question.
No national medicines regulator has approved epitalon as a therapeutic product. It is generally distributed as a research chemical, and in some jurisdictions selling peptides for human consumption without approval is restricted or prohibited. Certificates of analysis accompanying commercial material vary in which tests are performed, and independent verification of identity and purity is uncommon. Statements about anti-ageing or disease-prevention benefits on vendor pages are marketing claims rather than regulatory findings, a distinction that shapes how the compound is discussed in scientific and popular sources alike.
The most frequently cited laboratory finding is that AEDG increased telomerase activity and extended telomere length in cultured human somatic cells. That work used fetal fibroblast strains and reported changes in enzyme activity alongside altered division counts. Replication by unrelated groups has been limited, and the published record is largely a single-laboratory series rather than a multi-centre programme. The result supports a hypothesis about peptide influence on gene expression in cell culture; it does not by itself establish an effect on telomere length in living animals or in people.
Chemically, the molecule consists of four amino acid residues joined by three peptide bonds, with a free N-terminal amino group and a free C-terminal carboxyl group. Its molecular formula is C14H22N4O9, and its monoisotopic mass is approximately 390 daltons. The acidic glutamate and aspartate side chains give the peptide a net negative charge near neutral pH, a property that shapes its chromatographic behaviour and solubility profile. No disulfide bridges or other post-translational modifications are present, so the primary sequence alone defines the structure.
Most experimental work has been carried out in cell culture and animal models. Several reports describe changes in telomerase activity and proliferation in cultured cells, while rodent studies have examined lifespan, melatonin rhythm and reproductive endpoints. Human data remain limited, and much of the published clinical material consists of small trials with incomplete reporting of methods and controls. Whether the cell and animal findings translate into measurable effects in people is an open question, and the mechanistic basis of the reported telomerase changes is not fully established.
Discussions in the literature often conflate three distinct entities: the pineal extract epithalamin, the isolated tetrapeptide AEDG, and commercial preparations sold under similar names. Reviews citing older Russian-language studies sometimes omit detail on purity, route of administration and control groups, which makes cross-study comparison difficult. Researchers working with the compound generally note the need for independent replication, standardized enzyme assays, and clearer reporting of peptide identity. These caveats are relevant when weighing claims that appear in secondary sources rather than in primary reports.
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.
== History == The effectiveness and safety of apitegromab were evaluated in a 52-week randomized, double-blind, placebo-controlled trial (NCT05156320). The trial enrolled 188 participants with spinal muscular atrophy between 2 to 21 years of age who were not able to move or walk independently. All participants were already receiving an approved survival motor neuron 2-targeted treatment. Participants were randomly assigned to receive apitegromab 10 mg/kg, apitegromab 20 mg/kg via intravenous infusion, or placebo once every four weeks for approximately one year. The primary analysis was conducted in 156 participants aged 2 to 12 years of age.
== Further research == The role of the NET in many brain disorders underlies the importance of understanding the (dys)regulation of the transporter. A complete model of the proteins that associate with the transporter will be useful in designing drug therapies for diseases such as schizophrenia, affective disorder, and autonomic disorders. Recently discovered mechanisms of the NET, including the ability to act reversibly and as an ion channel, provide other areas of research.
The modifications covered in this diagram have to do with stereochemistry and the assignment of unique Cahn-Ingold-Prelog R/S assignments to complex analogues of fentanyl. The stereochemistry of fentanyl analogues can seem at first counter-intuitive, because of the complex and unique nature of the reasoning organic chemists must develop to internalize complex three dimensional geometries such as those needed to comprehend stereochemistry. Thankfully these images follow a simple procedure for organizing a potential analogue of fentanyl into the total number of unique stereoisomers, the number of true stereocenters on the molecule, and the number of Cahn-Ingold-Prelog R/S assignments that are appropriate for that analogue. The procedure used in the analysis of stereochemistry in these series of images is the following:
Sources: en.wikipedia.org
==== Identification of the formula ==== In the early 1700s, Georg Ernst Stahl claimed that reacting sulfuric acid with limestone produced a sort of alum. The error was soon corrected by Johann Pott and Andreas Marggraf, who showed that the precipitate obtained when an alkali is poured into a solution of alum, namely alumina, is quite different from lime and chalk, and is one of the ingredients in common clay. Marggraf also showed that perfect crystals with properties of alum can be obtained by dissolving alumina in sulfuric acid and adding potash or ammonia to the concentrated solution. In 1767, Torbern Bergman observed the need for potassium or ammonium sulfates to convert aluminium sulfate into alum, while sodium or calcium would not work. At the time, potassium ("potash") was believed to be exclusively found on plants. However, in 1797, Martin Klaproth discovered the presence of potassium in the minerals leucite and lepidolite. Louis Vauquelin then conjectured that potassium was likewise an ingredient in many other minerals. Given Marggraf and Bergman's experiments, he suspected that this alkali constituted an essential ingredient of natural alum. In 1797 he published a dissertation demonstrating that alum is a double salt, composed of sulfuric acid, alumina, and potash. In the same journal volume, Jean-Antoine Chaptal published the analysis of four different kinds of alum, namely, Roman alum, Levant alum, British alum and alum manufactured by himself, confirming Vauquelin's results.
== Overdose == Only a single case of death due to mescaline, as peyote, has been described, and was likely due to asphyxiation by vomit rather than overdose or toxicity. However, there is also a case report of death due to jumping off a cliff while on a high dose of mescaline. In terms of extrapolated human lethal dose based on animal studies, the lethal dose of mescaline relative to a typical recreational dose has been estimated to be 24-fold or around 8,400 mg. However, mescaline has reportedly been taken by humans at doses of up to 8,000 mg without apparent toxic reactions. On the other hand, there is one unverified reported case of death due to a dose of 15,000 mg intravenously, which would equate to about 150 to 200 mg/kg. The median lethal dose (LD50) of mescaline has been determined in various animal species, with the values including 212 to 315 mg/kg i.p. in mice, 132 to 410 mg/kg i.p. in rats, 328 mg/kg i.p. in guinea pigs, 54 mg/kg in dogs, and 130 mg/kg i.v. in rhesus macaques, among others. It has been said that it would be difficult to take enough mescaline to cause death in humans. No deaths due to peyote use have been reported aside from the asphyxiation case. The highest dose of peyote known to have been taken is 90 dried buttons.
== Induction of interferons == Production of interferons occurs mainly in response to microbes, such as viruses and bacteria, and their products. Binding of molecules uniquely found in microbes—viral glycoproteins, viral RNA, bacterial endotoxin (lipopolysaccharide), bacterial flagella, CpG motifs—by pattern recognition receptors, such as membrane bound toll like receptors or the cytoplasmic receptors RIG-I or MDA5, can trigger release of IFNs. Toll Like Receptor 3 (TLR3) is important for inducing interferons in response to the presence of double-stranded RNA viruses; the ligand for this receptor is double-stranded RNA (dsRNA). After binding dsRNA, this receptor activates the transcription factors IRF3 and NF-κB, which are important for initiating synthesis of many inflammatory proteins. RNA interference technology tools such as siRNA or vector-based reagents can either silence or stimulate interferon pathways. Release of IFN from cells (specifically IFN-γ in lymphoid cells) is also induced by mitogens. Other cytokines, such as interleukin 1, interleukin 2, interleukin-12, tumor necrosis factor and colony-stimulating factor, can also enhance interferon production.
Consumption of 1–1.5 grams (1,000–1,500 mg) per day is associated with a condition known as caffeinism. Caffeinism usually combines caffeine dependency with a wide range of unpleasant symptoms including nervousness, irritability, restlessness, insomnia, headaches, and palpitations after caffeine use. Caffeine overdose can result in a state of central nervous system overstimulation known as caffeine intoxication, a clinically significant temporary condition that develops during, or shortly after, the consumption of caffeine. This syndrome typically occurs only after ingestion of large amounts of caffeine, well over the amounts found in typical caffeinated beverages and caffeine tablets (e.g., more than 400–500 mg at a time). According to the DSM-5, caffeine intoxication may be diagnosed if five (or more) of the following symptoms develop after recent consumption of caffeine: restlessness, nervousness, excitement, insomnia, flushed face, diuresis, gastrointestinal disturbance, muscle twitching, rambling flow of thought and speech, tachycardia or cardiac arrhythmia, periods of inexhaustibility, and psychomotor agitation. According to the International Classification of Diseases (ICD-11), cases of very high caffeine intake (e.g. > 5 g) may result in caffeine intoxication with symptoms including mania, depression, lapses in judgment, disorientation, disinhibition, delusions, hallucinations or psychosis, and rhabdomyolysis.
Sources: en.wikipedia.org
Mass spectrometry provides the identity check, because the observed mass is compared with the theoretical mass of the AEDG sequence. Chromatography separates and quantifies impurities but does not by itself prove which peptide is present. The two techniques are normally used together.
Yes. Trifluoroacetate and acetate ions remain associated with the peptide after purification, so a weighed quantity of powder contains less peptide than the nominal mass suggests. Certificates that report net peptide content rather than raw weight are more directly comparable between suppliers.
Dilute aqueous solutions are less stable than the dry powder and are usually aliquoted and frozen to avoid repeated freeze–thaw cycles. Lyophilised material is best stored desiccated at −20 °C, protected from light. Working solutions are typically prepared fresh from a frozen aliquot.
It is a synthetic tetrapeptide built from alanine, glutamate, aspartate and glycine. The four residues are joined by standard peptide bonds, giving a linear chain rather than a branched structure.