For Epithalon storage and stability, keep the lyophilized powder sealed, dry, dark and cold. Its main weak point is not oxidation. It is isomerization at the Asp-Gly bond, which runs in water and makes an isobaric isoaspartyl form. Dry storage holds that reaction back, while any water that reaches the solid starts it again.
- Epithalon is the tetrapeptide Ala-Glu-Asp-Gly, formula C14H22N4O9, average mass about 390.35 g/mol for the free acid.
- Its dominant degradation route is succinimide-mediated isomerization at the Asp-Gly bond, producing an isoaspartyl form of identical mass.
- Because the isomer is isobaric, LC-MS confirms mass without confirming structural integrity, and resolution depends entirely on the chromatographic method.
- The lyophilized salt is hygroscopic, so equilibrating a sealed vial to room temperature before opening is the main defense against condensation uptake.
- Water drives both routes: isomerization speeds up at neutral and higher pH, and backbone hydrolysis speeds up at low pH.
- Net peptide content on the certificate, not gross fill mass, is the figure that says how much peptide the vial holds.
What is Epithalon, and why does it behave unlike most research peptides?
Think of it like dried pasta versus cooked pasta. In the box it keeps for a long time, but once water touches it the clock starts. For Epithalon, water lets one bond (Asp-Gly) slowly rearrange into a look-alike form with the same mass, which is why the dry powder is the stable state.
Epithalon, also written epitalon and often labeled AEDG, is the synthetic tetrapeptide H-Ala-Glu-Asp-Gly-OH. Molecular formula C14H22N4O9 for the free acid, monoisotopic mass near 390.14, average mass about 390.35 g/mol. Four residues. No aromatic side chains, no sulfur, no secondary structure to speak of.
That composition sets the handling problem in a different place than it sits for larger peptides. Two free carboxylic acid side chains plus the C-terminal carboxyl give the molecule three acidic groups against a single primary amine, so its isoelectric point sits low and it is freely soluble in water across most of the useful pH range. There is no hydrophobic face to drive aggregation and no lipid conjugate to make it interface-active. Adsorption losses to glass are correspondingly minor.
What the composition does deliver is hygroscopicity. Small, highly polar peptide salts pull water out of room air readily, and the lyophilized cake from a 10 mg fill is a thin film that can be hard to see at all. Two practical consequences follow: the vial must be treated as moisture-sensitive in the strict sense, and the material lost to static cling on the stopper is a real fraction of a small fill rather than a rounding error.
- Water — enables the Asp-Gly succinimide route, the dominant failure
- pH — isomerisation rises toward neutral and above, hydrolysis rises below
- Temperature — a rate modifier on both routes
- Ambient humidity — the hygroscopic cake takes up condensation on a cold vial
- Oxygen and interfaces — minor here, no Met, Trp, Cys or lipid tail
Why is the Asp-Gly bond the whole stability story?
Position 3 is aspartate and position 4 is glycine. That pairing is the single fastest-isomerizing sequence context known for aspartyl residues, and it is the reason this tetrapeptide needs more care around water than its simplicity suggests.
The mechanism is intramolecular. The backbone nitrogen of the following residue attacks the aspartate side-chain carbonyl, closing a five-membered cyclic imide, the succinimide. Glycine has no side chain, so nothing sterically obstructs that attack; every other residue at that position slows it down. The succinimide then opens by hydrolysis to give a mixture of the original α-linked aspartyl peptide and the β-linked isoaspartyl peptide, with isoAsp usually favored. Geiger and Clarke established the sequence dependence and pH profile of this chemistry on model peptides in 1987, and the ranking they reported has held up.
Two things about the product matter for anyone reading a certificate. First, isoAsp has the same molecular formula and the same mass as the parent, so mass spectrometry alone does not see it. Second, the succinimide intermediate racemizes easily, so the same pathway seeds D-aspartate content that a routine achiral method will also miss.
So the honest summary of Epithalon stability is that the compound converts, in water, into an isomer that most quality-control methods report as the compound. Keeping it dry is what prevents that.
Which degradation routes matter, ranked for this sequence?
| Route | Relevance here | Driver | Control |
|---|---|---|---|
| Succinimide formation and isoAsp | Primary | Water activity, pH near neutral and above, temperature | Dry solid storage; keep water away from the cake |
| Asp-Gly backbone hydrolysis | Secondary | Water, low pH, temperature | Dry storage; keep away from strong acid and heat |
| Racemization at Asp | Secondary, tied to the succinimide | Same conditions as isomerization | Same as above; detected only by chiral analysis |
| Moisture uptake by the solid | High, because the salt is hygroscopic | Ambient humidity, cold vials opened warm-room | Equilibrate sealed, work fast, reseal against desiccant |
| Oxidation | Low | Oxygen, light, trace metals | No Met, Trp or Cys present; dark storage is still cheap insurance |
| Aggregation | Low | Interfaces, agitation | Tetrapeptide with no hydrophobic core |
Notice that most of the classic peptide anxieties do not apply and one specific reaction dominates. That is a more comfortable position than it sounds, because a single dominant route with a single dominant driver is straightforward to design storage around.
How should Epithalon storage change by physical state?
| State | Temperature | Light | Relative horizon | Why |
|---|---|---|---|---|
| Sealed powder, unopened | −20 °C or below, desiccated | Dark | Longest | Water excluded, isomerization effectively halted |
| Sealed powder, in use | 2 to 8 °C, desiccated | Dark | Shorter | Acceptable where the vial is consumed within a defined window |
| Powder in transit | Ambient | Dark, insulated | Days | Dry solid tolerates short excursions |
The horizons stay relative on purpose. Assigning a month count to a research lot means running the stability study on that lot, in that container, under those conditions, to something like the ICH Q1A framework. Without that data the window is unestablished, and a supplier quoting a confident shelf life without a study behind it is repeating a convention.
Why is condensation a problem for a nearly invisible cake?
Take a vial from a −20 °C freezer into a room at 22 °C and moderate humidity. The glass sits far below the dew point. Break the seal at that moment and water condenses onto the coldest surface available, which is the inside of the vial and the cake itself. A hygroscopic tetrapeptide salt takes that water up straight away, and the succinimide reaction that was frozen out now has a solvent.
Nothing about this announces itself. There is no color change, no visible film, and for a 10 mg fill there may be so little solid that a partially dissolved cake looks identical to a dry one. The vial goes back to the freezer with water inside it and the next person repeats the exercise.
The control is dull and it works. Let the sealed vial reach room temperature before breaking the seal, twenty to thirty minutes on the bench for a small vial, every time. Work quickly once open. Reseal into a desiccator rather than straight into the freezer if the vial will be reopened. Where the protocol tracks excursions, log the open time.
The same logic applies to any peptide; the tirzepatide storage guide works through it for a molecule with different failure modes.
How are identity and purity verified on a polar tetrapeptide?
Two analytical facts about this compound are worth knowing before reading anyone's certificate.
First, retention. Ala-Glu-Asp-Gly is very hydrophilic and retains poorly on conventional C18 under standard peptide gradients. A chromatogram showing the main peak at the very front of the run, near the injection disturbance, has not separated the analyte from anything. Competent methods use a stationary phase tolerant of high aqueous conditions, ion-pairing with trifluoroacetic acid, a polar-embedded or AQ-type C18, or a HILIC separation. USP general chapter <621> sets the system suitability expectations any of those methods should meet, and a certificate that reports purity without retention time, column, gradient and suitability data is reporting a number rather than a measurement.
Second, the isomer. The isoaspartyl form is isobaric with the parent, so LC-MS confirms molecular mass and not structural integrity. Whether the isomer is resolved depends entirely on the chromatography. In practice, most research-grade certificates for this compound do not claim to separate it, and the correct reading of a 98% area purity figure is 98% of material eluting in the main peak under that method, not 98% α-aspartyl peptide. Laboratories that need the distinction run a method developed for it and say so.
Beyond that, the documentation set worth expecting is unremarkable: mass spectrum with the observed [M+H]⁺ against the calculated value, HPLC trace with an integration table, water content, residual solvents, counterion identity and content, net peptide content, and a lot number that matches the vial label. Our quality standard sets out what we require on each lot.
How do you handle a sealed vial, step by step?
- Store the sealed, unopened powder at −20 °C or below, desiccated and dark.
- Before opening, let the sealed vial reach room temperature. The salt is hygroscopic, and condensation is the main risk.
- Find the cake before you open the vial. From a 10 mg fill it is a thin film that can be hard to see.
- Work quickly once the vial is open, and reseal into a desiccator if it will be reopened.
What is the regulatory position?
Epithalon holds no marketing authorization as a medicinal product in the United States, the European Union or the United Kingdom. It originated in Russian gerontology research on pineal peptide preparations, and whatever status it has under any other jurisdiction does not transfer. This document does not evaluate that biological literature and takes no position on it.
FDA's published evaluation of bulk drug substances nominated for use in compounding under section 503A placed epitalon in the category the agency identified as presenting significant safety risks, which excludes it from the 503A bulks list. Category assignments have been revised over time, so confirm the agency's current listing rather than relying on a secondary summary of it.
Research-grade material is supplied against a certificate covering identity and purity. That is a narrower claim than a drug substance specification and has never been a lawful route to human use.
Status verified 26 August 2026.
FOR LABORATORY AND IN-VITRO RESEARCH USE ONLY. NOT FOR HUMAN OR ANIMAL CONSUMPTION. NOT FOR PERSONAL, MEDICAL, DIAGNOSTIC, THERAPEUTIC, OR RECREATIONAL USE.
Bottom line
Epithalon storage comes down to keeping water away. Sealed, dry, dark and cold, the powder holds back isomerization at the Asp-Gly bond. Water reaching the solid starts that reaction, and the isoaspartyl form it makes has the same mass, so LC-MS will not flag it. Let every cold vial warm before opening, and read net peptide content on the certificate.
What is Epithalon studied for?
Published research on Epithalon investigates the areas below, which is a different question from what Epithalon will do for anyone, a claim about a living system that nothing on this site is sold for.
What it is. A man-made peptide of four building blocks.
What the research looks at. It appears in a limited set of animal and cell studies. The evidence behind it is far thinner than the volume of commercial writing about it suggests.
How it is thought to work. Not established. The published record is small, and much of the original work comes from a narrow group of researchers, which is a real limit when reading it.
What is not established. No approved product, no official standard, and no settled mechanism. Claims made for this compound in vendor copy routinely go well past what the sources they cite actually say.
The full record, including the certificate for the lot in stock, is on the Epithalon product page.
Common questions
How should Epithalon be stored?
Does lyophilized Epithalon need to be frozen?
Why does the Asp-Gly sequence matter so much?
Can I tell from a certificate of analysis whether isomerization has occurred?
Is oxidation a concern for this peptide?
Related guides: storage and stability
Sources
- Geiger and Clarke, Journal of Biological Chemistry, 1987. Model-peptide study of deamidation, isomerization and racemization at asparaginyl and aspartyl residues; establishes the sequence dependence and pH profile behind the Asp-Gly succinimide pathway described here.
- PubChem compound record for epitalon. Supports the sequence Ala-Glu-Asp-Gly, molecular formula C14H22N4O9 and the molecular mass figures used in the arithmetic.
- USP General Chapter <621> Chromatography. Sets the system suitability and reporting expectations against which an HPLC purity method for a highly polar peptide should be judged.
- FDA listings of bulk drug substances nominated for compounding under section 503A. Establishes that epitalon is not an approved drug substance and was placed in the category the agency identified as presenting significant safety risks; listings are revised, so verify the current version.
