Pinealon vs Epithalon: Two Khavinson Peptides Compared

Research-use-only context. This article summarizes published third-party scientific literature and laboratory practice. It is not medical advice, not a therapeutic or performance claim, and not a usage guide. US Prime Peptides products are supplied strictly for in vitro laboratory research and are not for human or veterinary use.

Pinealon and Epithalon are two of the shortest peptides in any research catalog, three and four residues respectively, and both come from the same St Petersburg research program that named them after the pineal gland. This article compares them by sequence, mass, charge, the hypotheses their originating group has proposed for how they act, which published findings they share and which belong to only one of them, and what a certificate can and cannot verify for a molecule this small.

The short answer: two acidic micro-peptides, one shared hypothesis

Pinealon is Glu-Asp-Arg (often written EDR), a tripeptide of about 418 Da. Epithalon, also spelled Epitalon, is Ala-Glu-Asp-Gly (AEDG), a tetrapeptide of about 390 Da. Both were designed by Vladimir Khavinson's group at the St Petersburg Institute of Bioregulation and Gerontology; Epithalon's sequence was derived from the amino-acid composition of a pineal extract called Epithalamin, and Pinealon was produced by the same design approach. Neither has an identified receptor. The group's working hypothesis for both is that the peptides enter the nucleus and bind DNA in a sequence-dependent way.

What they do not share is the specific literature. Epithalon has a small set of telomerase and telomere-length papers in human fetal fibroblasts and a negative in vitro melatonin result; Pinealon has a reactive-oxygen-species and ERK-signaling paper in rat and mouse cell preparations. Neither compound is an approved drug anywhere. The compound-level articles on Pinealon and Epithalon cover each in depth.

Pinealon: Glu-Asp-Arg

Pinealon's molecular formula is C₁₅H₂₆N₆O₈, average mass 418.4 Da. With two acidic side chains, one C-terminal carboxyl, one N-terminal amine and the guanidinium of arginine, it has a net charge near minus one at neutral pH and is extremely polar, which makes it hard to retain on a standard C18 column without an ion-pairing agent. The most cited primary paper is a 2011 Rejuvenation Research study by Khavinson, Ribakova and colleagues reporting that in rat cerebellar granule cells, neutrophils and PC12 pheochromocytoma cells the tripeptide reduced reactive-oxygen-species accumulation under oxidative stress, reduced propidium-iodide-positive necrotic death, and delayed the time course of ERK1/2 activation, with cell-cycle effects continuing at concentrations above those at which the ROS effect saturated. A 2020 Molecules review by Khavinson, Linkova and colleagues collects the group's later neuronal-culture work on the EDR peptide. A 2012 Bulletin of Experimental Biology and Medicine paper by Voicekhovskaya and colleagues examined this and related tripeptides in skin-cell cultures from young and old rats.

Epithalon: Ala-Glu-Asp-Gly

Epithalon's formula is C₁₄H₂₂N₄O₈, average mass 390.3 Da. It has no basic side chain, so with two acidic residues plus the C-terminus it sits near minus two at neutral pH, even more polar than Pinealon. A 2002 Neuroendocrinology Letters paper by Sibarov and colleagues states that the tetrapeptide was synthesized on the basis of the amino-acid composition of the pineal extract Epithalamin, which is the origin of the name.

The findings most associated with it are from human fetal lung fibroblasts. A 2003 Bulletin of Experimental Biology and Medicine paper by Khavinson, Bondarev and Butyugov reported that adding Epithalon to telomerase-negative cultures induced expression of the telomerase catalytic subunit, measurable telomerase activity and telomere elongation. A 2004 follow-up in the same journal by the same authors reported that cultures which had stopped dividing at passage 34 made ten further passages after exposure, which the authors describe as overcoming the Hayflick limit. A 2003 paper in the same journal by Khavinson, Shataeva and Chernova proposed the mechanism: conformational modeling suggested the tetrapeptide could bind nucleotide sequences in the promoter regions of the telomerase and RNA polymerase II genes.

The literature also contains a clean negative result. A 2003 Journal of Endocrinological Investigation paper by Djeridane, Khavinson and Anisimov perifused pineal glands from young and old Wistar rats with the tetrapeptide at 10^-4 to 10^-6 M and found no effect on basal or isoproterenol-stimulated melatonin secretion. The authors concluded that in vitro the peptide does not appear to control melatonin output from the rat pineal gland. That matters because the compound's name and marketing both lean on the pineal connection.

Side-by-side comparison

The table shows that the two are chemically close cousins, differing by one residue in length and one unit of charge, and that both carry the same evidentiary limitation: nearly every paper comes from the originating group and its collaborators.

What the two share: the nuclear-entry and DNA-binding hypothesis

The one mechanistic thread that covers both compounds is a pair of 2011 papers. In Biochemistry (Moscow), Fedoreyeva, Kireev and Khavinson showed that fluorescein-labeled Epithalon, Pinealon and Testagen (Lys-Glu-Asp-Gly) all produced fluorescence in the cytoplasm, nucleus and nucleolus of HeLa cells, and that the unlabeled peptides quenched the fluorescence of labeled deoxyribooligonucleotides and DNA-ethidium complexes with Stern-Volmer constants that depended on the peptide sequence, which the authors read as sequence-dependent peptide-DNA interaction. In Bulletin of Experimental Biology and Medicine, Khavinson, Fedoreyeva and Vanyushin reported that short peptides of two to four residues altered hydrolysis of lambda-phage DNA by the plant endonucleases WEN1 and WEN2 in a way that depended on DNA methylation status.

These are in vitro biophysical observations, and they are consistent with a DNA-binding hypothesis without proving it. No crystal or NMR structure of either peptide bound to DNA has been published, no independent laboratory has reproduced the quenching data, and the physical plausibility of a 390 Da tetrapeptide recognizing a specific promoter sequence is itself contested. A 2025 International Journal of Molecular Sciences overview by Araj and colleagues summarizes the Epithalon literature and its limits. The article on why a second laboratory matters applies the same replication logic to analytical testing.

What a certificate can verify for a 400 Da peptide

Peptides this small behave more like small molecules than like proteins on a certificate. Mass spectrometry gives a single protonated ion, [M+H]⁺ near 419.2 for Pinealon and 391.2 for Epithalon, with no charge-state envelope to deconvolute, so identity is unambiguous. HPLC is the harder measurement: both elute near the void volume on a C18 column in a standard water-acetonitrile gradient, and a certificate should state the column, ion-pairing agent and detection wavelength, because a purity figure obtained at 214 nm near the solvent front is only as good as the baseline. Neither contains an oxidizable residue, and neither has a chiral center that mass spectrometry would need to resolve beyond the standard L-configuration.

Net peptide content deserves more attention than usual. On a 10 mg label of a 400 Da peptide, counter-ion (acetate or trifluoroacetate), bound water and residual salts make up a larger fraction of the gross mass than they do for a 3 kDa peptide, so the gap between "purity" and "content" is wider. US Prime Peptides posts lot-matched certificates for Pinealon 10 mg and Epithalon 50 mg that report identity, HPLC purity, net peptide content, endotoxin, sterility and heavy metals from an independent US laboratory. The article on Khavinson short peptides covers the rest of the di-, tri- and tetrapeptide family.

Frequently Asked Questions

What is the difference between Pinealon and Epithalon?

Pinealon is the tripeptide Glu-Asp-Arg (418 Da); Epithalon is the tetrapeptide Ala-Glu-Asp-Gly (390 Da). Pinealon carries an arginine and sits near -1 charge; Epithalon has no basic residue and sits near -2. Both come from the Khavinson group and share a proposed DNA-binding mechanism, but their specific published findings differ.

Does Epithalon affect melatonin in the published literature?

Not in the one direct in vitro test. A 2003 study perifusing rat pineal glands with the tetrapeptide found no effect on basal or stimulated melatonin secretion. Claims linking Epithalon to melatonin rest on older extract (Epithalamin) work, not on the synthetic tetrapeptide.

Has the Epithalon telomerase finding been independently replicated?

No. The telomerase and telomere-elongation results in human fetal fibroblasts come from a 2003-2004 pair of papers by the originating group, and no independent laboratory has published a replication.

Are Pinealon or Epithalon approved drugs?

No. Neither is an approved drug in the United States or elsewhere. Research vials are supplied only for in vitro laboratory work.

Citations

1. Khavinson V, Ribakova Y, Kulebiakin K, et al. Pinealon increases cell viability by suppression of free radical levels and activating proliferative processes. Rejuvenation Res. 2011;14(5):535-541. PMID 21978084
2. Khavinson V, Linkova N, Kozhevnikova E, Ilina A. EDR Peptide: Possible Mechanism of Gene Expression and Protein Synthesis Regulation Involved in the Pathogenesis of Alzheimer's Disease. Molecules. 2020;26(1):159. PMID 33396470
3. Voicekhovskaya MA, Chalisova NI, Kontsevaya EA, et al. Effect of bioregulatory tripeptides on the culture of skin cells from young and old rats. Bull Exp Biol Med. 2012;152(3):357-359. PMID 22803085
4. Sibarov DA, Kovalenko RI, Malinin VV, Khavinson VKh. Epitalon influences pineal secretion in stress-exposed rats in the daytime. Neuro Endocrinol Lett. 2002;23(5-6):452-454. PMID 12500171
5. Khavinson VKh, Bondarev IE, Butyugov AA. Epithalon peptide induces telomerase activity and telomere elongation in human somatic cells. Bull Exp Biol Med. 2003;135(6):590-592. PMID 12937682
6. Khavinson VKh, Bondarev IE, Butyugov AA, Smirnova TD. Peptide promotes overcoming of the division limit in human somatic cell. Bull Exp Biol Med. 2004;137(5):503-506. PMID 15455129
7. Khavinson VKh, Shataeva LK, Chernova AA. Effect of regulatory peptides on gene transcription. Bull Exp Biol Med. 2003;136(3):288-290. PMID 14666197
8. Djeridane Y, Khavinson VKh, Anisimov VN, Touitou Y. Effect of a synthetic pineal tetrapeptide (Ala-Glu-Asp-Gly) on melatonin secretion by the pineal gland of young and old rats. J Endocrinol Invest. 2003;26(3):211-215. PMID 12809170
9. Fedoreyeva LI, Kireev II, Khavinson VKh, Vanyushin BF. Penetration of short fluorescence-labeled peptides into the nucleus in HeLa cells and in vitro specific interaction of the peptides with deoxyribooligonucleotides and DNA. Biochemistry (Mosc). 2011;76(11):1210-1219. PMID 22117547
10. Khavinson VKh, Fedoreyeva LI, Vanyushin BF. Site-specific binding of short peptides with DNA modulated eukaryotic endonuclease activity. Bull Exp Biol Med. 2011;151(1):66-70. PMID 22442805
11. Araj SK, Brzezik J, Mądra-Gackowska K, et al. Overview of Epitalon: Highly Bioactive Pineal Tetrapeptide with Promising Properties. Int J Mol Sci. 2025;26(6):2691. PMID 40141333

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