Epitalon (Epithalon)

1 Identity

Short-chain bioregulator (Khavinson class) — synthetic linear all-L tetrapeptide. and "pineal tetrapeptide". CAS commonly listed by suppliers as 307297-39-8, which is a market attribution and not verified against a primary chemical registry. Do not treat epithalamin or Endoluten as a synonym: that is a bovine pineal extract of undefined composition, listed separately in the catalog, and the conflation of the two literatures is the central marketing defect in this article's market.

Sequence

H-Ala-Glu-Asp-Gly-OH (AEDG). Four residues, all L and all proteinogenic; free N-terminal alpha-amino group; free C-terminal carboxyl; no disulfide, no acylation, no amidation, no non-proteinogenic residue. Gly4 is achiral, so the molecule carries three stereocenters and not four. Three carboxyl functions, the Glu2 side chain, the Asp3 side chain and the C-terminal Gly, against a single basic center, the N-terminal amine, so the peptide is strongly acidic and is supplied as the acetate or trifluoroacetate of that one amine. No aromatic residue, therefore NO 280 nm chromophore, which makes a 280 nm purity trace on this article a positive finding rather than a footnote: it indicates a method copied from somewhere else.

Molecular formula

C14H22N4O9 (free acid). PubChem CID 219042 carries the same formula. One reagent catalog sells it as the trifluoroacetate, and the salt must be written into the product identity, not left in a footnote.

Average mass

390.349 Da, from the tetrapeptide composition with IUPAC 2021 conventional atomic weights. The "approximately 390.3" that circulates rounds the same value. The number is not the problem on this article; the 0.044 Da neighbor under the salt and variant note is.

Monoisotopic mass

390.13868 Da neutral. Working ions: [M+H]+ m/z 391.14596, [M-H]- m/z 389.13140, [M+Na]+ m/z 413.12790. A plus or minus 5 ppm window on the neutral is plus or minus 0.0020 Da. Negative mode is the sensible primary on a molecule with three carboxylates and one amine, and it is also where the Vesugen discrimination described below is cleanest.

Salt / variant note

(1) the 0.044 Da problem. Vesugen, H-Lys-Glu-Asp-OH (KED), C15H26N4O8, 390.393 avg / 390.17506 mono. On average mass the two peptides are 0.044 Da apart, closer than the rounding on most catalog pages, and monoisotopically they are 93 ppm apart, which a high-resolution instrument separates easily and a unit-resolution quadrupole does not. Both are sold at 20 mg from the same Khavinson shelves by the same sellers. This is the single most important line in this record. (2) N-Acetyl Epitalon Amidate, Ac-AEDG-NH2, C16H25N5O9, 431.402 avg / 431.16523 mono, plus 41.05 on the parent; listed separately in the catalog. (3) N-acetyl epitalon free acid, C16H24N4O10, 432.386 avg / 432.14924 mono, plus 42.04, one dalton from the amidate and routinely confused with it. (4) Cortagen, H-Ala-Glu-Asp-Pro-OH, 430.414 avg, which differs from epitalon only by Gly-to-Pro. (5) Chonluten, H-Glu-Asp-Gly-OH, 319.270 avg, epitalon minus the N-terminal Ala. (6) EPITHALAMIN / ENDOLUTEN, the bovine pineal extract, panel P7, no mass at all: a supplier substituting the extract for the tetrapeptide, or the reverse, is trading between two different regulatory categories, and the extract direction carries ruminant CNS tissue with it. (7) Permutations of AEDG are isobaric with each other and are separable only by MS/MS or Edman.

2 Class & testing panel

Form

Single article

Testing panel

P1 — panel definition

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

Study types and identifiers only; no statement is made here of what any study reported. In vitro, human cell lines: Al-Dulaimi, Thomas, Matta and Roberts, Biogerontology 2025, PMID 40908429, with a subsequent published erratum at PMID 41240216, and readers must consult the corrected version. Narrative review: Araj, Brzezik, Madra-Gackowska and Szeleszczuk, Int J Mol Sci 2025;26(6):2691, PMID 40141333, DOI 10.3390/ijms26062691, which states that physico-chemical and structural investigation of this peptide remains limited. Animal, mouse: Anisimov SV and colleagues, Bull Exp Biol Med 2002, PMID 12360356. Animal, transgenic mouse: Anisimov VN and colleagues, Bull Exp Biol Med 2002, PMID 12459848. In vitro, mouse oocytes: Yue and colleagues, Aging (Albany NY) 2022, PMID 35413689. In vitro: Gatta and colleagues, Stem Cell Rev Rep 2025, PMID 40493162. NO registered human clinical trial of epitalon, epithalon or AEDG appears anywhere in ClinicalTrials.gov. No established receptor is reported in the primary literature located. Critical separation: the lifespan literature routinely cited under this name used EPITHALAMIN, the bovine pineal extract, not the synthetic tetrapeptide, and belongs to a different article. Evidence grade D.

4 Storage & specification

Storage

Lyophilized powder, -20 degrees C plus or minus 5 degrees C, desiccated with in-pack desiccant, protected from light; 2 to 8 degrees C acceptable for transit and for working stock held no longer than 30 days. Acetate preferred over trifluoroacetate and specified on the purchase order. Sealed vials are equilibrated to room temperature before opening: on a 390 Da peptide, condensation onto cold solid moves the water figure enough to move the net peptide claim, and the net peptide claim is the label.

Shelf life

Provisional 24 months at -20 degrees C plus or minus 5 degrees C, assigned by protocol and not measured, pending the company's long-term and accelerated data on the first three lots at 0, 3, 6, 9, 12, 18 and 24 months. No Cys, no Met, no Trp and no disulfide, so oxidation and scrambling are not pathways here; the attributes to trend are water content, counterion and the Asp3 succinimide and iso-aspartate route under low-pH storage in solution. The label is shortened on data and is never extended without a completed 24-month dataset.