Selank / Semax: structure and analysis

What is Selank / Semax?

A two-compound blend supplied in a single vial: Selank at 5 mg and Semax at 5 mg. The notation 5/5mg states each component's mass.

Both components are heptapeptides built on the same design principle — a short active fragment extended with a proline-glycine-proline tail that slows enzymatic degradation — but from different parent sequences. Selank derives from tuftsin, Semax from the 4-7 fragment of adrenocorticotropic hormone.

So this vial contains two peptides of identical length and similar design, which is the most analytically awkward arrangement in the catalogue.

How is Selank / Semax produced?

Supplied as a blend: the named components are combined and co-lyophilized into a single vial, with the mass of each component stated. The components are produced separately and characterised before combination.

This changes the analytical question. For a single compound, purity asks what share of the detected material was the target. For a blend there are several targets, and what matters is whether each named component is present at its stated mass — per-component identification and quantitation rather than one purity percentage.

What is in Selank / Semax?

Selank / Semax is supplied as one co-lyophilized vial holding 2 separately characterised components, in the ratio 5/5mg. A blend has no single molecular formula, because a formula describes one molecule and this vial holds several, so the table gives each component's own published figures.

For a neutral molecule the ion a mass spectrometer is compared against is the protonated species, [M+H]⁺. Two of these components are already charged — a copper complex and a quaternary ammonium — and for those the ion to compare against is the species itself; the table says which is which.

Two masses describe each of these molecules and they are different numbers: the monoisotopic mass, which assumes every carbon is carbon-12, and the tallest peak in the isotope envelope, which for a long peptide sits one or two carbon-13 substitutions above it. The table gives the monoisotopic figure; each component's own page gives both.

What a certificate can establish for a vial like this is a separate identity and a separate quantitation for each named component, each against a standard appropriate to that molecule. One purity percentage does not describe several targets, and the certificate has to be read per analyte rather than as one number.

How does Selank / Semax compare with related compounds?

Related compounds are not interchangeable. Published figures differ between them, and in this catalogue three compounds share a GHRH backbone while several share the same structural class — which is exactly why identity is confirmed analytically rather than inferred from the label.

How is the identity of Selank / Semax confirmed?

Both components require independent identity confirmation, and here that is genuinely more demanding than for other blends. Two heptapeptides sharing a proline-glycine-proline extension have more in common than a tripeptide and a 43-residue peptide do.

Their masses differ because their active fragments differ, so mass spectrometry distinguishes them — but the margin is smaller than in any other blend here.

Which impurities can appear in Selank / Semax?

Two peptides of the same length with a shared structural motif are the hardest pair in the catalogue to resolve chromatographically. Similar size and similar composition mean similar retention, so the separation has to be developed for this specific pair rather than adapted.

There is an asymmetry in stability worth noting. Semax contains an N-terminal methionine and is therefore susceptible to oxidation to the sulfoxide; Selank contains no methionine, cysteine or tryptophan and has no comparable pathway. Methionine sulfoxide is a plausible impurity in this vial, arising from one component only.

That also means the vial's storage conditions are effectively set by Semax, the less chemically robust of the two.

What does a certificate of analysis for Selank / Semax report?

A certificate for a batch of this material names the batch, names the issuing laboratory, and states for each parameter both the method used and the specification the result was measured against. Identity and purity are the two core results; net peptide content states how much of the fill weight is actually peptide.

A certificate belongs to a batch, not to a product line. When a new batch is released it is tested again, and the certificate published against it is that batch's certificate — a previous batch's result is never carried forward.

Is Selank / Semax for human use?

No. This page describes structure and analysis. It makes no claim about what this compound does, and none should be inferred from it. Material is supplied for laboratory research use only: it is not a drug, food, dietary supplement, cosmetic or medical device, it is not for human or veterinary consumption, and no dosing, administration or reconstitution guidance is provided for any such use.

Common questions

What is in Selank / Semax?

One vial contains Selank at 5 mg and Semax at 5 mg. The ratio 5/5mg on the product states each named component's mass in that order, and the components are combined and dried together in that one vial rather than supplied as separate vials.

Does Selank / Semax have a single purity figure?

No. Purity in the peptide sense describes one target measured against its own impurities, and this vial has 2 targets. Each component's purity is meaningful only against its own reference standard, so a certificate for this blend reports per-component results rather than one percentage for the vial.

Is Selank / Semax supplied pre-mixed?

It is supplied as a single sealed vial of co-lyophilized powder: the named components are combined before drying, and nothing is supplied as a liquid or reconstituted before dispatch. Each component's mass is stated in the ratio on the product page and on its batch certificate.

How is each component of Selank / Semax established?

Each named component is identified and quantified against its own reference standard, with the method stated beside the result. Read the certificate per analyte rather than as one number: one row per component, a stated method, and a result measured against a stated specification. A certificate that reports a single purity figure for a vial like this has characterised one component and implied it characterised all of them.

Is Selank / Semax for human or veterinary use?

No. It is supplied for laboratory research use only, and it is not a drug, food, dietary supplement, cosmetic or medical device. No dosing, administration or reconstitution guidance is provided for any human or animal use, in any channel.

References

• Selank — PubChem, National Library of Medicine
• ACTH (4-7), Pro-Gly-Pro (Semax) — PubChem, National Library of Medicine
• Pro-opiomelanocortin — human — UniProt Knowledgebase