Epitalon USA

A four-residue peptide should be the simplest thing in a catalogue to verify, and chemically epitalon is. What complicates it is everything around the chemistry: three spellings in circulation, a 390 Da molecule that barely sticks to a reversed-phase column, and a salt form that makes up a larger share of the vial than people expect. This page deals with each in turn and ends with ordering within the United States.

Epitalon, epithalon, epithalone

These are one compound: the tetrapeptide Ala-Glu-Asp-Gly, written AEDG, monoisotopic mass 390.35 Da. The spellings are transliteration variants from the Russian literature, where the compound was described as a synthetic analog of a fragment of the pineal extract epithalamin. The label on a vial is a naming choice; the certificate should report an AEDG sequence and a mass of 390 Da regardless. Epitalon: a review of the evidence goes through the primary literature and what it does and does not support, and short peptide bioregulators covers the family of tetrapeptides it belongs to.

Analysing a 390 Da peptide

Two things make a tetrapeptide certificate look different from a 30-mer’s. First, the molecule is small and polar, so on a standard reversed-phase gradient it elutes early, close to the void, and its impurities, which are mostly deletion and truncation products of two or three residues, elute right beside it. A laboratory doing the method properly starts the gradient at low organic and reports a sharp, early main peak. A certificate run on a generic 5-to-65% gradient written for long peptides may still give an honest purity figure, but the chromatogram tells you little. Gradient elution for peptide HPLC explains why the method has to fit the molecule.

Second, there is no aromatic residue, so there is no absorbance at 280 nm at all. Detection must be at 210 to 220 nm, where the peptide bond absorbs, and a certificate claiming 280 nm detection for this compound should be questioned. ELSD and CAD for peptides without a chromophore covers the alternatives some laboratories use.

The salt form matters more here

Epitalon has two carboxylate side chains and a C-terminal acid, so the acetate or trifluoroacetate counter-ion and bound water together account for a larger fraction of the gross vial mass than they do for a long peptide. A 10 mg label is gross content unless the certificate says otherwise. Where quantitation matters, use the net peptide content figure if the laboratory reports it. Amino acid analysis and net peptide content covers the measurement, and counter-ions and salt forms the conversion.

In solution

Lyophilised epitalon is stable at minus 20 °C and is not especially hygroscopic. It dissolves readily in water. In solution the Asp-Gly junction is a textbook site for isoaspartate formation, which produces an impurity of identical mass and shifted retention time. Stock solutions should be made fresh or kept frozen in aliquots rather than stored at 4 °C for weeks. Deamidation and the 0.98 Da shift describes what the related asparagine chemistry looks like on re-analysis.

What we supply

Epitalon 10 mg is supplied as a single lyophilised vial at 99%+ purity. Published certificates are on the certificates page, and vials are matched to their report by cap and crimp colour.

Ordering in the USA

Orders ship domestically within the United States, so there is no import processing and no customs hold. USPS, UPS and FedEx services are offered at checkout, dispatch is within one business day and typical transit is two to five days. The per-milligram price list puts epitalon in context against the rest of the catalogue.

Research use only

Epitalon from ExoLabz is a laboratory reference material for in vitro and analytical research. It is not a drug, not a supplement, and not for human or veterinary use, and we do not provide dosing or administration information. The purity guarantee applies to every vial.