Epithalon (also written Epitalon) is a synthetic tetrapeptide, Ala-Glu-Asp-Gly, designed in the 1980s from the amino acid composition of a polypeptide extract of pineal gland tissue. It is used in cell culture studies of telomerase expression, chromatin state and gene transcription, where a four-residue acidic peptide is a compact tool for asking how short peptides reach the nucleus. Epithalon from NuVion is supplied as a laboratory chemical for in vitro research use only.
Key facts
| Type | Synthetic peptide, tetrapeptide |
| Amino acid count | 4 |
| Sequence | Ala-Glu-Asp-Gly (AEDG) |
| Molecular formula | C14H22N4O9 |
| Molecular weight | 390.35 g/mol |
| CAS number | 307297-39-8 |
| Synonyms | Epitalon, Epithalone, AEDG peptide |
| Supplied form | Lyophilised powder in a sealed vial |
Epithalon
$59 AUD
View productResearch use only. Not for human or veterinary use.
Structure and chemistry
Two of the four residues carry carboxylate side chains, and with the C-terminal carboxylate the peptide has three negative charges balanced by a single N-terminal amine, so at neutral pH the net charge is about minus 2 and the molecule is very hydrophilic. It dissolves readily in water and aqueous buffers. The same property makes it poorly retained on C18 columns under standard acidic mobile phases, so RP-HPLC methods for it tend to use low organic content at the start of the gradient, an ion-pairing agent or a polar-embedded stationary phase to obtain a usable retention time. There are no aromatic residues, so detection is at 210 to 220 nm.
The Asp-Gly sequence at the C-terminus is the classic site of succinimide-mediated isomerisation to isoaspartate, a slow process at neutral pH that accelerates with heat. With no cysteine, methionine, tryptophan or histidine, oxidation is not a concern. The practical issue in cell work is that a free, unmodified tetrapeptide is a good substrate for the aminopeptidases and dipeptidyl peptidases in serum-containing culture medium, so its half-life in complete medium should be expected to be short and working solutions are made up fresh.
Epithalon was designed by Khavinson and colleagues at the St Petersburg Institute of Bioregulation and Gerontology. The tetrapeptide was assembled from the most abundant residues in Epithalamin, a polypeptide fraction extracted from pineal gland tissue, in the way a consensus sequence is derived from a protein family, and then made by solid-phase synthesis. It is not a fragment of any single characterised protein.
Mechanism of action
No receptor is known and none is proposed. The working hypothesis of the group that developed the peptide is that short, charged peptides cross the plasma and nuclear membranes and bind DNA or chromatin proteins directly, changing the accessibility of particular promoters. That hypothesis rests on molecular modelling, on peptide-DNA binding measured by spectroscopy, and on gene expression changes in cultured cells. It has not been confirmed by structural methods, most of the published in vitro work comes from a single group, and independent replication is limited. The observations below should be read in that light.
Telomerase. In cultured human somatic cells (fetal fibroblast lines), addition of Epithalon has been reported to induce expression of the catalytic subunit of telomerase (TERT), to give measurable telomerase activity by TRAP assay in cells that lack it, and to lengthen telomeres over subsequent passages, with the cultures continuing to divide past the point at which control cultures reached replicative senescence. Telomerase expression is transcriptionally repressed in differentiated somatic cells, so the claim is one of derepression at the TERT locus, which is consistent with the chromatin observations that follow.
Chromatin. In cultured lymphocytes, the peptide has been reported to decondense pericentromeric heterochromatin and to activate nucleolar organiser regions, both of which are readouts of a shift toward transcriptionally open chromatin. Molecular modelling places the tetrapeptide in the major groove of DNA at particular sequences and on linker histone H1 subtypes, with electrostatic contacts from the two carboxylate side chains. Modelling generates hypotheses; there is no crystal or NMR structure of the peptide bound to DNA or to a histone.
Gene expression. In human gingival mesenchymal stem cells, exposure to the peptide increased transcripts and protein for the neuronal differentiation markers nestin, GAP43, β-tubulin III and doublecortin. In pinealocyte cultures, increased expression of arylalkylamine N-acetyltransferase (AANAT), the rate-limiting enzyme of melatonin synthesis, and of phosphorylated CREB has been reported. These readouts fit a transcription-level mechanism but do not identify the target.
Research applications
- TRAP telomerase activity assays and TERT qPCR in cultured fibroblasts with and without peptide exposure
- Telomere length by qPCR or terminal restriction fragment analysis across passages, alongside population doubling counts
- Chromatin readouts: heterochromatin staining, nucleolar organiser region silver staining, ATAC-seq or histone mark ChIP in exposed cultures
- Peptide-DNA and peptide-histone interaction by fluorescence quenching, circular dichroism and docking
- Differentiation marker expression in mesenchymal stem cell cultures, and AANAT and CREB phosphorylation in pinealocyte cultures
- RP-HPLC method development for short acidic peptides with poor C18 retention
Epithalon sits in the Cellular Ageing category with the other compounds used in telomere, mitochondrial and NAD-dependent signalling work.
Handling in the laboratory
The lyophilised powder is reconstituted with bacteriostatic water. It dissolves almost immediately; run the water down the inside of the vial and swirl. The reconstitution calculator gives the concentration that a chosen water volume produces from the vial content. Because the peptide is a diacid, a concentrated stock in unbuffered water will be mildly acidic, so for cell work the stock is diluted into buffered medium and the final pH checked if the addition is more than a small percentage of the volume.
Keep the sealed vial dry, away from light and refrigerated as described in the product documentation. Once reconstituted, keep the solution refrigerated and use it within the period stated on the documentation, and aliquot to avoid repeated freeze-thaw cycles. The compound is characterised by RP-HPLC for purity and by mass spectrometry for identity. On electrospray in positive mode the singly charged ion is observed near m/z 391; negative mode, where the carboxylates ionise readily, gives a stronger signal near m/z 389 and is often the better choice for this peptide.
Testing and supply from NuVion
NuVion has Epithalon independently tested by Janoshik Analytical. Most batches are tested, and the Certificate of Analysis for a tested batch is published on the product page, reporting purity by RP-HPLC and identity by mass spectrometry. Manufacture is GMP-audited, the peptide is supplied lyophilised in sealed vials, and orders are dispatched from within Australia. Certificates for other compounds are collected in the Certificate of Analysis library.
Related compounds
The nearest relative is Pinealon, the Glu-Asp-Arg tripeptide from the same design programme, used in gene expression work in neuronal cell models. NAD+, the coenzyme substrate for sirtuins and PARPs, and GHK-Cu, the copper-binding tripeptide, are the other compounds in the category used in chromatin and gene expression assays.
Frequently asked questions
What is Epithalon used for in research?
Epithalon is used in cell culture studies of telomerase expression and activity, telomere length across passages, chromatin condensation state and transcription of specific genes. It is also used in biophysical work on peptide-DNA and peptide-histone binding, and as a test analyte in RP-HPLC method development for short, poorly retained acidic peptides.
What is the evidence that Epithalon affects telomerase?
Reports of TERT induction, TRAP-detectable telomerase activity and telomere lengthening come from cultured human fibroblast lines, and most of them come from the group that designed the peptide. The proposed mechanism is direct binding to DNA or histone H1 with derepression of the TERT promoter, which rests on modelling and spectroscopy and not on a solved structure. Independent replication with modern chromatin methods is limited.
How is Epithalon supplied and stored?
NuVion supplies Epithalon as a lyophilised powder in a sealed vial. Store the sealed vial dry, away from light and refrigerated per the product documentation. After reconstitution with bacteriostatic water, keep the solution refrigerated and use it within the period given on the documentation.
Is Epithalon a therapeutic good in Australia?
No. Epithalon from NuVion is a laboratory chemical for in vitro research. It is not included in the Australian Register of Therapeutic Goods and has not been assessed by the TGA. It is not for human or veterinary use.
Research use only. This product is a laboratory chemical supplied for in vitro research. It is not included in the Australian Register of Therapeutic Goods and has not been assessed by the Therapeutic Goods Administration for quality, safety or efficacy. It is not for human or veterinary use, and nothing on this page is a representation about therapeutic use.
