Semax and Selank: The Russian Neuropeptides Explained

Semax and Selank are two synthetic heptapeptides developed in Russia and licensed there as medicines. They are often discussed together because they share a design trick and a research tradition.

The shared design: a Pro-Gly-Pro tail

Both peptides take a short, biologically active fragment and add Pro-Gly-Pro to the C-terminus. That tripeptide tail slows breakdown by peptidases, making the fragment last longer than it otherwise would.

Neither is licensed in the UK. Research-grade material is for laboratory use only.

Semax

Semax is built from ACTH(4-10), a fragment of adrenocorticotropic hormone. It has no meaningful action on the adrenal glands.

Research themes include:

• Neurotrophic signalling. Rodent studies report increased BDNF and TrkB expression in the brain.
• Monoamine systems. Effects on dopaminergic and serotonergic markers.
• Ischaemia models. Experimental stroke and hypoxia studies in animals.

Selank

Selank is built from tuftsin, an immunomodulatory tetrapeptide derived from immunoglobulin G.

Research themes include:

• GABAergic modulation. Proposed allosteric effects on GABA-A receptors.
• Enkephalin metabolism. Inhibition of enzymes that break down enkephalins.
• Immune and cytokine markers, reflecting tuftsin's origin.

Acetylated and modified variants

Variant	Modification	Note
N-acetyl Semax	N-terminal acetyl (sometimes also C-terminal amide)	Check which modifications are present
N-acetyl Selank	N-terminal acetyl	Limited independent data
Adamax	Semax-related with an adamantane group	Name used inconsistently between sellers

Each modification changes molecular weight, so price-per-mg comparisons are only fair within the same form.

Limits of the evidence

Most published work comes from Russian institutions, much of it in Russian-language journals, and independent Western replication is limited. Mechanisms are proposed rather than firmly established.

Comparing listings

1. Confirm the exact variant on the certificate of analysis. See how to read a CoA.
2. Compare price per mg within the same variant.
3. Check the format. Some products are sold as solutions rather than lyophilised powder, which changes how you compare them.

Summary

Semax and Selank are stabilised fragments of ACTH and tuftsin, with research literature on neurotrophic and GABAergic signalling that comes mostly from Russia. PeptideCompare provides no dosing or usage guidance, and nothing here is for human or veterinary use.