Epithalon

Epithalon, also written Epitalon and abbreviated AEDG, is the linear tetrapeptide Ala-Glu-Asp-Gly. It carries no terminal modification, no cysteine and no unnatural residue. Two of its four residues are acidic, so the molecule is strongly negatively charged at neutral pH and behaves in solution more like a small organic acid than like a typical peptide.

It was designed as a short synthetic representative of epithalamin, a polypeptide preparation from pineal tissue, and belongs to the class described in the literature as peptide bioregulators. No receptor has been identified for it. The mechanistic proposals in the literature involve direct interaction with nucleic acid sequences and transcriptional effects rather than binding at a cell-surface target, which is a materially different kind of claim and worth reading as such.

Telomerase activity is the endpoint most closely associated with this compound, typically measured by the telomeric repeat amplification protocol in cultured somatic cell lines, with telomere length by Southern blot or quantitative PCR as the supporting measurement. Pineal and retinal explant preparations appear in the gene expression literature.

Lifespan and ageing-marker work has been reported in Drosophila melanogaster and in rodent models, and much of the primary literature originates from a single research group and is published in Russian-language journals. That concentration of provenance is a real feature of the evidence base for this compound and is worth weighing when designing an experiment around it.

Identity is easy to establish and rarely the problem. At 390 daltons the molecule is small enough that mass spectrometry is decisive, and the four-residue sequence leaves little room for ambiguity. One practical detail matters for chromatography: the peptide contains no tryptophan, tyrosine or phenylalanine, so it does not absorb at 280 nanometres and must be detected at 210 to 220 nanometres by the peptide bond itself.

The specification that separates lots is net peptide content. A short, strongly acidic sequence is hygroscopic and retains both water and counterion from purification, so material can be 98 percent pure by HPLC area while a meaningful fraction of the vial mass is water and trifluoroacetate. Amino acid analysis or nitrogen determination reports the actual peptide mass, and for a compound weighed out at small scale that difference propagates directly into every concentration calculated from it.