Epitalon

Epitalon is a synthetic linear tetrapeptide, among the smallest and structurally simplest compounds in this library. Four standard residues, free termini, no modifications of any kind — there is genuinely very little chemistry to it, and this page says so rather than padding.

Identity and classification

Epitalon is described in the literature as a synthetic analogue of a peptide preparation of pineal origin. No receptor or molecular target is assigned to it in reference-supplier catalogue classification, and we make no claim about one. It is supplied as a sequence-defined synthetic tetrapeptide.

A naming distinction worth noting: “Epithalamin” refers to a peptide extract preparation, not to a single defined molecule. Epitalon (also spelt Epithalon) is the defined synthetic tetrapeptide. The names are used interchangeably in some sources, but an extract and a synthetic tetrapeptide are not the same class of material, and only the latter can carry a molecular formula and a purity figure.

Structure

H-Ala-Glu-Asp-Gly-OH. Four standard L-amino acids in ordinary α-peptide linkage, with a free N-terminal amine and a free C-terminal acid. No cyclisation, no disulfide bonds, no D-amino acids, no non-natural residues, no amidation, no acylation.

The composition is strikingly acidic: a glutamate and an aspartate side chain alongside a C-terminal carboxyl give three carboxylic acids against a single amine. This makes the peptide strongly anionic at neutral pH, very highly water-soluble, and poorly retained on reverse-phase columns — a point that matters for its analysis.

Specification and characterisation

• Reverse-phase retention is poor. A small, highly polar, triply-anionic tetrapeptide has little to interact with on C18 and can elute at or near the void volume, where separation from polar impurities is worst. Ion-pairing agents such as TFA improve it; ion-exchange or HILIC chromatography may be more appropriate. An RP-HPLC purity figure for Epitalon should be read with the method in view — a high area percent obtained at the void volume is not a meaningful purity statement.
• No aromatic residues. As with Selank, 280 nm detection is uninformative. Purity is assessed at 214 nm.
• Mass confirmation against 390.35. Negative-ion mode is often the better choice for a strongly acidic peptide.
• Aspartate-related rearrangement. Asp-Gly is the classic sequence context for succinimide formation and isoaspartate rearrangement, and Epitalon contains exactly that motif at residues 3–4. The isoaspartyl product is isobaric — identical mass — so mass spectrometry will not detect it. This is the specification point that matters most for this peptide and the one least likely to appear on a certificate.
• Amino acid analysis confirming the 1:1:1:1 composition.
• Counter-ion and water content. An acidic peptide is more likely to be supplied as a sodium or ammonium salt than as an acetate.

Handling and stability

Store sealed at 2–8 °C, dry, protected from light. Equilibrate in a desiccator before opening.

There is no cysteine, no methionine, no tryptophan and no asparagine, so the oxidative and deamidation routes described elsewhere in this library do not apply. The relevant chemical liability is the Asp-Gly rearrangement above, which is accelerated at neutral to alkaline pH and by elevated temperature — so as a dry, cool, sealed solid the peptide is stable, and it is solution storage that introduces the risk.

Related compounds in this library

KPV is the other very short linear peptide of standard residues, though it is basic where Epitalon is acidic, and the two have opposite chromatographic behaviour for that reason. Selank shares the absence of aromatic residues and the resulting 214 nm-only detection.

References

Chemical, specification and analytical sources. This list is deliberately limited to chemistry and analytical references.

• Cayman Chemical, Epitalon record — formula, molecular weight, sequence
• ChemicalBook, CAS 307297-39-8 — registry and formula confirmation
• Chemsrc, Epitalon — independent mass confirmation
• Bachem, Handling and Storage Guidelines for Peptides — aspartate rearrangement, polar peptide handling

Cosmic Aminos supplies this material as a laboratory reagent for in-vitro research use only. It is not a drug, food, cosmetic or dietary supplement, is not approved by the Food and Drug Administration for any use, and is not for human or veterinary consumption. No dosing, administration or preparation guidance is provided.