Epitalon, also referenced in the literature as epithalon or the AEDG peptide, is a synthetic tetrapeptide of alanine, glutamic acid, aspartic acid and glycine. It was derived from epithalamin, a pineal gland extract characterised in Soviet and Russian gerontology work from the 1970s onward, and the four-residue sequence is the isolated fragment that preparation was attributed to. Its brevity is the research property: at under 400 daltons it can be synthesised to a single defined sequence and holds that sequence across an assay window, which the parent extract, a mixture of many peptides, cannot.

The mechanism examined most often is transcriptional. Published work reports induction of the telomerase reverse transcriptase subunit, TERT, in somatic cell cultures, with telomere length and population doubling as the measured endpoints. A second line of investigation treats the peptide as a gene-expression modulator on its own terms, using it in chromatin-accessibility and promoter-binding studies where the question is whether a tetrapeptide associates with DNA directly rather than through a receptor. Circadian and pineal-axis models form the third context, examining melatonin synthesis enzymes and clock gene expression in pinealocyte preparations.

Much of the foundational literature is Russian-language and predates independent replication, a limitation that literature states of itself, and it is one reason Epitalon continues to attract laboratory investigation rather than settling into consensus. Epitalon is catalogued here as a reference compound for laboratory research. The findings above are drawn from cell-culture and animal models. No therapeutic, diagnostic, or clinical conclusion is drawn from them, and none should be inferred.