Are Semax and Selank the same class of peptide?

Both are synthetic heptapeptides, but they derive from different parent molecules: Semax from an ACTH fragment and Selank from tuftsin.

Why do both end in the same three residues?

Both were designed with a proline-glycine-proline extension, a structural strategy intended to increase resistance to enzymatic degradation.

Are these approved for human use?

Not in the United States. Both are supplied by Amino Fuel Labs as research material only and are not for human or veterinary use.

How are they distinguished analytically?

By chromatographic retention behavior combined with accurate mass measurement, since the two differ in composition despite similar chain length.

Research Comparison Reference

Semax vs Selank: Peptide Origin and Structure Comparison

A structural reference for two short synthetic heptapeptides that derive from entirely different parent molecules.

Attribute comparison

Verified attribute comparison for Semax vs Selank: Peptide Origin and Structure Comparison
Attribute	Semax	Selank
Compound class	ACTH(4-7)-derived heptapeptide	Tuftsin-derived heptapeptide
Peptide or non-peptide	Peptide	Peptide
Amino-acid count	7	7
Receptor or pathway classification	Not established	Not established
Molecular weight	813.86 g/mol	751.87 g/mol
Physical form	Lyophilized powder	Lyophilized powder
Laboratory research context	Neuropeptide signaling studies	Neuropeptide signaling studies
Available from Amino Fuel Labs	Yes	Yes

Key structural differences

Both molecules are seven residues long and both were developed as synthetic analogs of naturally occurring fragments, but the parent molecules differ. Semax is built from an adrenocorticotropic hormone fragment extended with a proline-glycine-proline tail. Selank is built from the immune-related tetrapeptide tuftsin, extended with the same style of stabilizing tail.

The shared proline-glycine-proline extension is a structural design choice rather than a shared origin, and the two sequences are otherwise unrelated.

Their molecular weights sit within roughly sixty daltons of each other, which is why analytical methods used to distinguish them rely on retention behavior and mass accuracy rather than on size alone.

Published research context

Both peptides have been investigated in research literature originating largely in Russian-language and subsequently indexed international publications. Neither has an approved finished-product status in the United States.

This reference does not describe outcomes, effects, or applications in people.

Frequently asked questions

Are Semax and Selank the same class of peptide?: Both are synthetic heptapeptides, but they derive from different parent molecules: Semax from an ACTH fragment and Selank from tuftsin.
Why do both end in the same three residues?: Both were designed with a proline-glycine-proline extension, a structural strategy intended to increase resistance to enzymatic degradation.
Are these approved for human use?: Not in the United States. Both are supplied by Amino Fuel Labs as research material only and are not for human or veterinary use.
How are they distinguished analytically?: By chromatographic retention behavior combined with accurate mass measurement, since the two differ in composition despite similar chain length.

References

PubMed — Semax research literature — National Library of Medicine
PubMed — Selank research literature — National Library of Medicine

Research use only. The information in this library is educational and is not medical advice. Products are not intended to diagnose, treat, cure, or prevent disease and are not for human or veterinary consumption.