counterion 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 2026-02-28. Where a claim depends on a specific study, the study is described rather than over-claimed.
Human data are limited to small studies, often without the randomization, blinding, or control groups expected in contemporary clinical research. Reported outcomes have included changes in melatonin levels, immune markers, and subjective measures, but sample sizes were generally too small to support firm conclusions. Some reviews treat the peptide as promising while noting methodological weaknesses; others question whether the observed effects are specific. The compound is frequently discussed in longevity-focused communities, where enthusiasm often outpaces the published evidence. Separating established findings from speculation is therefore important when reading summaries of this research.
Epitalon emerged from research conducted in Saint Petersburg by Vladimir Khavinson and colleagues, who studied short peptides as potential regulators of aging. The work built on epithalamin, a pineal gland extract reported to influence neuroendocrine function. Epitalon was designed as a synthetic counterpart with a defined sequence, allowing reproducible experiments that extracts could not support. Early publications described effects on melatonin rhythms and lifespan in animal models. These findings circulated mainly in Russian-language journals during the 1990s, which limited their visibility among English-speaking researchers.
Solubility is high in water, phosphate-buffered saline and normal saline, a pattern that follows from the two acidic residues in the chain. The peptide dissolves poorly in non-polar solvents such as hexane or chloroform. Stock solutions are often prepared in water first and then diluted into the buffer of interest. Because the molecule is small and hydrophilic, filtration through a low-protein-binding membrane is usually straightforward, and visible particulates are uncommon in freshly made solutions.
Identity and purity are established with reversed-phase high-performance liquid chromatography and mass spectrometry. The chromatogram shows the main peak and any truncated or oxidised by-products, while the mass spectrum confirms the expected 390 dalton mass. Amino acid analysis can corroborate composition when a sample's origin is uncertain. Counterion content, particularly residual trifluoroacetate from purification, is frequently reported alongside purity because it shifts the net mass of the solid.
| Property | Value | Notes |
|---|---|---|
| Peptide sequence | Ala-Glu-Asp-Gly | Single-letter form AEDG |
| Compound class | Synthetic tetrapeptide | Not a natural free peptide |
| Research origin | Russian gerontology institutes | Developed during the 1990s |
| Main research claim | Telomerase activation | Evidence mainly from cultured cells |
| Regulatory status | Not an approved drug | Handled as a research material |
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.
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.
There had been Jewish tribes in Aden and Yemen for millennia, where they had primarily constituted the artisans and craftsmen of these areas, but it was after the British occupation of 1839 that Aden became an important congregation. During the two World Wars the Jews in Aden had prospered while those in Yemen suffered. The Balfour Declaration had encouraged increased Jewish immigration into the Holy Land, and as a result many of the Jewish communities from all over the Middle East sought a new home there. The Palestine issue had a serious effect on British prestige in Aden. During the Second World War, Jews from Yemen flocked in large numbers into Aden while en route to Mandatory Palestine, where they were placed in refugee camps, primarily for their own safety. However conditions in the camps were difficult and in 1942 there was an outbreak of typhus. The outbreak of the anti-Jewish riots in December 1947, following the UN declaration for the creation of a Jewish state, left at least 70 Jews were killed and much of the Jewish Quarter burned and looted. Until this point nearly all the refugees had been from Yemen and the Aden Protectorate, but now after the growing violence against Jews in the Town itself, most tried to leave. The riots left the Jewish community with the sense that their personal safety and long-term financial security were at risk, with more than 2,800 Jewish residents having left Aden and made it to Israel by 1950. Population figures which showed roughly 4,500 Jews in 1947 had dropped to less than 500 in 1963.
=== Iodothyronine deiodinase === Central to human (and vertebrate in general) thyroid hormone metabolism are three iodothyronine deiodinases, with gene symbols DIO1, DIO2, DIO3 in humans. Related proteins have been found in invertebrate chordates, mostly with a selenocystine, though a few have cystine instead.
=== Transcriptional regulation === Histones can be ubiquitinated, usually in the form of monoubiquitylation, although polyubiquitylated forms do occur. Histone ubiquitylation alters chromatin structure and allows the access of enzymes involved in transcription. Ubiquitin on histones also acts as a binding site for proteins that either activate or inhibit transcription and also can induce further post-translational modifications of the protein. These effects can all modulate the transcription of genes.
=== Transcriptional === CHS is constitutively expressed in plants but can also be subject to induced expression through light/ UV light and well as in response to pathogens, elicitors and wounding. The CHS promoter contains a G-box motif with a sequence of CACGTG. This has been shown to play a role in response to light. Other light sensitive domains include Box I, Box II, Box III, Box IV or three copies of H-box (CCTACC). The chalcone synthase gene of Petunia plants is famous for being the first gene in which the phenomenon of RNA interference was observed; researchers intending to upregulate the production of pigments in light pink or violet flowers introduced a transgene for chalcone synthase, expecting that both the native gene and the transgene would express the enzyme and result in a more deeply colored flower phenotype. Instead the transgenic plants had mottled white flowers, indicating that the introduction of the transgene had downregulated or silenced chalcone synthase expression. Further investigation of the phenomenon indicated that the downregulation was due to post-transcriptional inhibition of the chalcone synthase gene expression via an increased rate of messenger RNA degradation.
Sources: en.wikipedia.org
In 1893, Prof. Niels Ryberg Finsen (1860–1904) began to treat lupus vulgaris, a tubercular condition of the skin, in the direct mode with heat-filtered light from a carbon arc lamp. He established the Phototherapy treatment at the Whitechapel Hospital in London, which had a Light Department in the first decade of the 20th century. His activity had royal patronage, and Niels Ryberg Finsen received the Nobel Prize in 1903. In 1894, neurologist and psychiatrist Edward Flatau published a human brain atlas, "Atlas of the Human Brain and the Course of the Nerve-Fibres," which consisted of long-exposure photographs of fresh brain sections. It contained an overview of the knowledge of the time on the fibre pathways in the central nervous system. In 1924, the German psychiatrist Hans Berger attached electrodes to the scalp and detected small currents in the brain. In the 1940s, the US War Department investigated the use of electrical stimulation and used so-called "galvanic exercises" on the atrophied hands of patients with ulnar nerve damage from wound surgery, not only to slow and prevent atrophy, but also to restore muscle mass and strength. In the mid-20th century, the scientific study of neuromodulation in humans expanded significantly. Neurologist Professor Spiegel and neurosurgeon Professor Weissys of Temple University presented a stereotactic device to perform "ablation procedures" in humans; in 1947, "intraoperative electrical stimulation" was introduced to test the brain's target zone before surgery.
From here he would address 180,000 listeners, some standing in the central round arena, others seated in three concentric tiers of seats crowned by one hundred marble pillars, 24 metres (79 ft) tall, which rose to meet the base of the coffered ceiling suspended from steel girders sheathed on the exterior with copper. The three concentric tiers of seats enclosing a circular arena 140 metres (460 ft) in diameter owe nothing to the Pantheon but resemble the seating arrangements in Ludwig Ruff's Congress Hall at Nuremberg, which was modeled on the Colosseum. Other features of the Volkshalle's interior are clearly indebted to Hadrian's Pantheon: the coffered dome, the pillared zone, which here is continuous, except where it flanks the huge niche on the north side. The second zone in the Pantheon, consisting of blind windows with intervening pilasters, is represented in Speer's building by a zone above the pillars consisting of uniform, oblong shallow recesses. The coffered dome rests on this zone. The design and size of the external decoration of this Volkshalle, are all exceptional and call for explanations that do not apply to community halls planned for Nazi fora in other German cities. The temple-like nature of the domed building was noted by Speer, who surmised that the building was ultimately intended for public worship of Hitler, his successors and the German Reich, that is, it was to be a dynastic temple/palace complex of the kind Augustus built on the Palatine, where his modest house was connected to the temple of Apollo.
There are also many references to the heart in the Christian Bible, including "Blessed are the pure in heart, for they will see God", "Above all else, guard your heart, for everything you do flows from it", "For where your treasure is, there your heart will be also", "For as a man thinks in his heart, so shall he be." The expression of a broken heart is a cross-cultural reference to grief for a lost one or to unfulfilled romantic love. The notion of "Cupid's arrows" is ancient, due to Ovid, but while Ovid describes Cupid as wounding his victims with his arrows, it is not made explicit that it is the heart that is wounded. The familiar iconography of Cupid shooting little heart symbols is a Renaissance theme that became tied to Valentine's Day. In certain Trans-New Guinea languages, such as Foi and Momoona, the heart and seat of emotions are colexified, meaning they share the same word.
Sources: en.wikipedia.org
Vladimir Khavinson and colleagues at research institutes in Saint Petersburg developed and studied the peptide. Their program examined short peptides as regulators of aging and neuroendocrine function. Epitalon was one of several compounds produced by that group.
That question is not settled. Cell culture studies have reported increased telomerase activity after treatment, but comparable evidence from controlled human trials is lacking. Any claim about telomere lengthening in people should be treated as unproven.
It has not completed the large, controlled trials required for drug approval in major jurisdictions. Most human reports involve small samples and limited follow-up. As a result, it is sold as a research chemical rather than a licensed pharmaceutical product.
Sealed lyophilised powder is normally kept at minus twenty degrees Celsius or below, away from light and moisture. Vials are allowed to reach room temperature before opening to limit condensation. Repeated warming and cooling of the same vial is discouraged.