Epithalon

The tetrapeptide Ala-Glu-Asp-Gly, also written Epitalon. One of the shortest chains in the PepXtide structural library, where its computed mass matches the published molecular weight.

The peptide was designed from the amino-acid composition of Epithalamin, a polypeptide extract of bovine pineal gland described in the literature from the 1970s, by a programme led by Khavinson and Anisimov. The earliest indexed primary papers on the defined tetrapeptide date from 2000. Epithalamin and Epitalon are not the same material, and public database synonym lists conflate them, so a citation to one should not be read as evidence about the other.

Structurally it is as simple as a peptide gets: four L-residues joined by ordinary alpha-peptide bonds, with a free N-terminal amine and a free C-terminal acid, plus free side-chain carboxyls on the glutamate and the aspartate. There is no cyclisation, no acylation, no amidation and no D-residue. Commercial material is generally supplied as an acetate or trifluoroacetate salt, which the certificate should state.

The catalogue will be direct about the evidence, because this is the compound in the range where popular claims run furthest ahead of published work. The frequently repeated account that the peptide induces telomerase and elongates telomeres rests on reports in telomerase-negative human fetal fibroblasts published from 2003 onward. A literature search on the peptide together with telomerase or telomeres returns only around a dozen records in total, of which the primary studies came from a single research group for roughly two decades; the first independent primary replications appeared in 2025, and one carries a published correction. The proposed binding of the peptide to DNA or to gene promoters comes from molecular modelling, not from a measured binding experiment such as a crystal structure, isothermal titration calorimetry or a gel-shift assay. A review published in 2025 states plainly that the mechanism remains unverified.

Reported work on the pineal gland is internally contradictory in the same way, with a direct effect on melatonin-synthesis enzymes reported in pinealocyte culture but no effect on melatonin secretion found in perifused pineal preparations at any concentration or age.

The physicochemical record is close to empty, and that is itself the useful handling fact. A 2025 review states that the quantity of physicochemical and structural investigation of this peptide remains very limited, and no published solubility, stability, half-life or absorption measurements were located. Note what the chemistry implies in their absence: an unmodified tetrapeptide with a free N-terminus and a free C-terminal acid is a textbook substrate for both aminopeptidases and carboxypeptidases, and claims that it is resistant to hydrolysis do not trace to primary data. Treat it as labile in any matrix with peptidase activity until a specific measurement says otherwise.