Semax and Selank: Russian nootropic peptides

Semax and Selank are the best-known representatives of the Russian school of neuropeptides. Both derive from natural peptides, both were developed in an academic setting, and both are frequently mentioned in discussions of cognition, stress and nootropics.

That is precisely why it matters to distinguish between three things: origin, mechanism and clinical evidence.

Semax: an ACTH(4–10) analogue

Semax is a heptapeptide with the sequence MEHFPGP. Its core derives from the ACTH(4–10) fragment — part of adrenocorticotropic hormone that is associated with the stress response, but not with the full hormonal activity of ACTH.

The addition of Pro-Gly-Pro at the C-terminus is intended to increase stability and improve passage into the brain. This modification is precisely what distinguishes the short fragment from Semax.

Proposed mechanisms

In preclinical studies, researchers reported:

• increased BDNF expression and activation of the TrkB pathway;
• an effect on neuroplasticity and synaptic signalling;
• modulation of the stress response;
• protective effects in ischaemia models.

BDNF is an attractive target because it is involved in learning, memory and neuronal survival. However, an increase in BDNF in a particular model is only a signal, not proof of improved cognition in humans.

Selank: tuftsin and anxiety

Selank is a heptapeptide TKPRPGP, designed as an analogue of tuftsin, an immunopeptide involved in the functioning of the immune system. In Selank too, the Pro-Gly-Pro addition is intended for stability.

It has been studied mainly in relation to:

• anxious behaviour in animal models;
• BDNF expression;
• GABAergic and monoaminergic signalling;
• immune markers.

GABA is the main inhibitory neurotransmitter, so the hypothesis of a calming effect is biologically plausible. But the path from receptor to feeling is long and full of intervening variables.

What is common to the Russian research tradition?

In the Soviet and Russian setting, neuropeptides were studied intensively from the 1970s onwards. Researchers developed a range of compounds that were later registered for certain neurological indications. This tradition produced a rich literature, but also specific methodological patterns:

• small clinical samples;
• often open-label studies without blinded controls;
• publication in domestic journals;
• limited independent replication in the international setting.

This does not mean the data are worthless. It means they must be read with the context in mind.

What should a good study show?

To assess a cognitive or anxiolytic effect seriously, we would need:

1. Randomisation and a control group (placebo).
2. Blinded assessment of outcomes.
3. Validated scales and objective measurements.
4. A sufficiently large sample to detect a real effect.
5. Independent replication in another laboratory.
6. Long-term safety monitoring.

For Semax and Selank, these conditions are not fully met in the international literature.

How to read the Russian literature?

Russian studies are often published in national journals that are not always indexed in international databases. This makes searching and assessing quality more difficult. When reading, pay attention to:

• sample size and the method of selecting participants;
• the control group and any placebo;
• blinded assessment of outcomes;
• statistical analysis and effect size;
• conflicts of interest and the funder;
• independent replication in another laboratory.

An English abstract does not mean the study is methodologically strong. Nor is a reference to “Russian clinical practice” a substitute for data.

Safety and regulation

In the EU, Semax and Selank are not approved as medicines. In Russia they were registered for certain indications, which is an important cultural and regulatory context, but not a permission for use in Croatia.

Possible adverse effects have not been sufficiently studied. With intranasal use, local reactions and the quality of the preparation must be taken into account. Laboratory research requires appropriate safety precautions.

Nootropics: realistic expectations

The term “nootropic” is often used loosely. A true nootropic substance should improve cognitive functions without major side effects, in healthy individuals as well. For most substances marketed as nootropics, this cannot be claimed.

Sleep, exercise, nutrition and stress management remain the factors with the most consistent evidence. No peptide replaces the basics.

Conclusion

Semax and Selank are historically important Russian neuropeptides with interesting preclinical mechanisms. Their clinical value in healthy people, however, remains unconfirmed. For research use, the key requirements are quality and analyses, purity, stability and a clearly defined model.

See Semax and Selank, or read why Russian peptides are of research interest.