This is a working overview of Tetrapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-05-04 and is reviewed periodically as new material appears.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Derived from the four-residue sequence |
| Molar mass | About 390.35 g/mol | Free peptide, counter-ion not included |
| Appearance | White to off-white powder | Lyophilised solid from aqueous solution |
| Water solubility | Freely soluble | Short, polar peptide chain |
| Common synonyms | AEDG; epithalone | Catalogues use the names interchangeably |
The Israeli Sayeret Matkal and Shaldag units have also been modelled after the SAS, sharing its motto. Ireland's Army Ranger Wing (ARW) also trains with the SAS. The Philippine National Police's Special Action Force was formed along the lines of the SAS. The former Royal Afghan Army's 666th Commando Brigade was formed by Colonel Rahmatullah Safi in the 1970s after he received his training with the SAS before it was disbanded through purges after the coups in 1973 and 1978.
There are over 800 extant species of cephalopod, although new species continue to be described. An estimated 11,000 extinct taxa have been described, although the soft-bodied nature of cephalopods means they are not easily fossilised. Cephalopods are found in all the oceans of Earth. None of them can tolerate fresh water, but the brief squid, Lolliguncula brevis, found in the Chesapeake Bay, is a notable partial exception in that it tolerates brackish water. Cephalopods are thought to be unable to live in fresh water due to multiple biochemical constraints, and in their >400 million year existence have never ventured into fully freshwater habitats. Cephalopods occupy most of the depth of the ocean, from the abyssal plains to the sea surface, and have also been found in the hadal zone. Their diversity is greatest near the equator (~40 species retrieved in nets at 11°N by a diversity study) and decreases towards the poles (~5 species captured at 60°N).
Flare-ups of autoimmune conditions such as systemic lupus erythematosus and rheumatoid arthritis may also occur during this period. Patients on tumor necrosis factor antagonists Patients with chronic inflammatory conditions (Crohn's disease, ulcerative colitis, sarcoidosis, etc.) are often treated with TNF antagonists, such as infliximab, adalimumab, and etanercept. Tumor necrosis factors are critical in macrophage activation and subsequent granuloma formation. Therefore, TNF antagonists impair the host immune response against infections such as tuberculosis. While the patient is taking TNF antagonists, these infections may remain latent and asymptomatic. However, when these medications are discontinued, there may be an associated pro-inflammatory response causing the infection to be uncovered.
Sources: en.wikipedia.org
== Use and effects == (R)-MDMA has a dose of 125 to 300 mg orally and a duration of 3.5 to 5.2 hours. It has been estimated that doses of 125 mg MDMA, 100 mg (S)-MDMA, and 300 mg (R)-MDMA are equivalent. The first modern clinical study of the comparative effects of MDMA, (R)-MDMA, and (S)-MDMA was published in August 2024. It compared 125 mg MDMA, 125 mg (S)-MDMA, 125 and 250 mg (R)-MDMA, and placebo. (R)-MDMA increased any drug effect, good drug effect, drug liking, stimulation, drug high, alteration of vision, and alteration of sense of time ratings similarly to MDMA and (S)-MDMA. However, (S)-MDMA 125 mg was more potent in increasing subjective effects, including stimulation, drug high, happy, and open, among others, than (R)-MDMA 125 or 250 mg or MDMA 125 mg. Ratings of bad drug effect and fear were minimal with MDMA, (R)-MDMA, and (S)-MDMA. In contrast to expectations, (R)-MDMA did not produce more psychedelic-like effects than (S)-MDMA. Besides subjective effects, (R)-MDMA increased heart rate, blood pressure, and body temperature similarly to MDMA and (S)-MDMA, though it was less potent in producing these effects. Body temperature was notably increased to the same extent with (R)-MDMA 250 mg as with MDMA 125 mg and (S)-MDMA 125 mg. The differences in effects between (R)-MDMA and (S)-MDMA may reflect the higher potency of (S)-MDMA rather than actual qualitative differences between the effects of (S)-MDMA and (R)-MDMA. It was estimated that equivalent effects would be expected with (S)-MDMA 100 mg, MDMA 125 mg, and (R)-MDMA 300 mg.
Proteins are frequently described as consisting of several structural units. These units include domains, motifs, and folds. Despite the fact that there are about 100,000 different proteins expressed in eukaryotic systems, there are many fewer different domains, structural motifs and folds.
== Advantages == A major advantage of the SELDI process is the chromatographic separation step. While liquid chromatography-mass spectrometry (LC-MS) is based on the elution of analytes in the separated sample, separation in SELDI is based on retention. Any sample components that interfere with analytical measurements, such as salts, detergents, and buffers, are washed away before analysis with mass spectrometry. Only the analytes that are bound to the surface are analyzed, reducing the overall complexity of the sample. As a result, there is an increased probability of detecting analytes that are present in lower concentrations. Because of the initial separation step, protein profiles can be obtained from samples of as few as 25-50 cells. In biological applications, SELDI-TOF-MS has a major advantage in that the technique does not require the use of radioactive isotopes. Furthermore, an assay can be sampled at multiple time points during an experiment. Additionally, in proteomics, the biomarker discovery, identification, and validation steps can all be done on the SELDI surface.
Sources: en.wikipedia.org
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.
The name derives from epithalamin, a pineal gland extract studied in the former Soviet Union. Researchers proposed that short fragments of that extract carried the biological activity of interest.
No major regulatory agency has approved it as a medicine. It is handled as a research chemical, and products sold under this name are not standardised drugs with defined clinical labelling.
Epitalon is a synthetic tetrapeptide built from four amino acids: alanine, glutamate, aspartate, and glycine. It is not extracted from a natural source but made in the laboratory by chemical synthesis. Its short length makes it relatively straightforward to produce at high purity.