Epithalon, epitalon and the word bioregulator

One tetrapeptide, four spellings, and a term that is not a pharmacological class. What AEDG is, where it came from, what the Khavinson school means by bioregulator, and its US status as of September 21, 2026.

By Touchstone PeptidesSeptember 22, 20266 minute read

Epithalon and epitalon are two spellings of the same molecule: the tetrapeptide Ala-Glu-Asp-Gly, written AEDG in one-letter code. It is a synthetic four-residue peptide with a molecular weight of 390.35, designed in St Petersburg to mimic the amino-acid composition of a bovine pineal extract called epithalamin. "Peptide bioregulator" is the term its originators use for this family of short synthetic peptides; it is a research school's label, not a pharmacological class and not a regulatory category.

The molecule

PubChem lists it under the title Epitalon (CID 219042) with the synonyms Ala-Glu-Asp-Gly, Epithalon, Epithalone and, confusingly, Epithalamin and Epithalamine, which are properly the names of the extract it was modelled on. The record gives:

Sequence: Ala-Glu-Asp-Gly (AEDG), four residues, all L-configuration, joined by ordinary alpha-peptide bonds
Formula: C14H22N4O9
Average molecular weight: 390.35
CAS: 307297-39-8 (PubChem also lists 64082-79-7)

Two of the four residues, glutamate and aspartate, carry acidic side chains, so the free peptide has three carboxyl groups and one amine and is strongly acidic at neutral pH. The Glu-Asp pair is also the part of the chain most exposed to hydrolysis in solution, a point covered in Where the 28 days number comes from. A 2025 review in the International Journal of Molecular Sciences notes that some authors skip the trade-style name and "refer only to its primary structure", AEDG, which is the least ambiguous way to write it.

The catalog lists it as Epitalon on the bioregulators shelf.

Where the name comes from

The 2025 review traces the lineage. In 1973 the term epithalamin was used for "a pineal polypeptide extract from cattle," and the early work on that extract was led by V. K. Khavinson and V. N. Anisimov. Epitalon, in the review's words, "was synthesized based on the amino acids composition of Epithalamin, a bovine pineal gland extract, prior to its discovery in pineal gland polypeptide complex solution." The synthetic tetrapeptide was designed from the bulk amino-acid analysis of the extract, and only later reported to be present in it.

That history explains the spelling problem. The Russian-language literature transliterates the name as epitalon; English-language papers and catalogs use epithalon, epithalone or epitalone; and epithalamin, the extract, keeps being attached to the peptide as a synonym. Searches for any of the four land on the same molecule. The one distinction that matters chemically is extract versus defined peptide: epithalamin is a mixture, AEDG is one compound with one mass.

What "peptide bioregulator" means, and what it does not

The phrase belongs to the St Petersburg Institute of Bioregulation and Gerontology, where Khavinson and colleagues developed a method for isolating polypeptide fractions from the organs of young animals and then synthesizing short peptides modelled on them. Their reviews describe "low molecular weight short peptides containing up to ten amino acid residues" and propose that they act by regulating gene expression in the tissue the parent extract came from. The 2025 epitalon review says it "is thought to be a tissue-specific peptide".

That is a hypothesis and a naming convention from one research group. It is not:

a chemical class. Bioregulators are ordinary short peptides made of ordinary amino acids; nothing in the structure distinguishes them from any other di-, tri- or tetrapeptide.
a regulatory category. FDA does not use the term. Epitalon was evaluated by FDA's Pharmacy Compounding Advisory Committee in July 2026 as "Epitalon (free base)" and "Epitalon acetate," a bulk drug substance like any other nominated peptide.
a statement of effect. The site describes what these peptides are and what they have been studied in. It does not repeat the claims made for them.

The published research base is mostly from the originating group and its collaborators. The 2025 review summarises studies in cultured cells (human fetal fibroblasts, lymphocytes, periodontal ligament stem cells), in Drosophila, and in rodents, and notes that "the quantity of physico-chemical and structural investigations of this peptide remains quite limited." Readers weighing the literature should know that most of it was produced by the people who named the class.

The family: pinealon, vilon, thymalin and the rest

The same school produced a set of related molecules, several of which are on the bioregulators shelf. They are not all the same kind of thing.

Name	What it is	Sequence	PubChem CID	CAS
Epitalon	synthetic tetrapeptide	Ala-Glu-Asp-Gly	219042	307297-39-8
Pinealon	synthetic tripeptide	Glu-Asp-Arg	10273502	175175-23-2
Vilon	synthetic dipeptide	Lys-Glu	7010502	45234-02-4
Thymogen	synthetic dipeptide	Glu-Trp	not verified here	not verified here
Thymalin	polypeptide complex extracted from calf thymus	mixture, no single sequence	none applicable	none applicable

Thymalin is the odd one out. Khavinson's own 2021 review describes it as "a polypeptide complex isolated from the thymus of calves," first reported in 1981, and describes thymogen (the dipeptide Glu-Trp), vilon (Lys-Glu) and a tripeptide Glu-Asp-Pro as its "components." An extract has no single mass and no sequence, so a certificate for thymalin cannot report identity the way a certificate for a defined peptide can; the product page's description, "thymus peptide complex," is the honest one. A note for anyone searching: a PubChem name lookup for "thymalin" returns thymulin, a defined nonapeptide from a different lineage, not thymalin.

The others are defined compounds. Pinealon is Glu-Asp-Arg, molecular weight 418.4, and vilon is Lys-Glu, molecular weight 275.3; both are on PubChem with the names above. Vilon and the other two-residue peptides in the catalog are discussed in The two-residue peptides. The catalog also lists Lys-Glu-Asp-Gly (testagen), Lys-Glu-Asp (vesugen) and Lys-Glu-Asp-Pro (prostamax), which follow the same design pattern of two to four mostly acidic and basic residues.

How to read a peptide sequence explains the notation.

Status as of September 21, 2026

Epitalon has no US approval and no ClinicalTrials.gov record. It sat in FDA's 503A Category 2 from September 29, 2023 until FDA's page dated April 22, 2026 moved it to the "nominated but withdrawn" section; it is now in no category and is not on the 503A bulks list. At the Pharmacy Compounding Advisory Committee on July 24, 2026 FDA proposed that neither epitalon free base nor epitalon acetate be listed; press reports give the vote as 7 in favor, 4 against, none abstaining, and FDA has published no official tally and no proposed rule. The full 2026 sequence is in Category 1, Category 2 and the 503A bulks list.

Epitalon is not named in WADA's 2026 Prohibited List; absence from the list's examples does not clear a substance, because the S0 catch-all covers any substance without approval from a governmental health authority.

Any registration outside the United States is not verified here and is not claimed.

Sources

For laboratory research use only. Not a drug, not a supplement, and nothing here is a claim about what any of this material does in a person or an animal.

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