Semax vs Selank: Russian Nootropic Peptide Comparison
By UK Peptide Lab Research Team•17 May 2026•7 min read
Russian Nootropic Peptide Research Background
Semax and Selank are both synthetic heptapeptides developed at the Institute of Molecular Genetics of the Russian Academy of Sciences from the 1980s onward. They share a similar molecular weight and route of administration but derive from entirely different parent molecules and act on distinct biological pathways. Both have been classified as nootropic research compounds in Russian preclinical literature. Neither is approved for clinical use in the UK by the MHRA. Semax and Selank are supplied for in-vitro laboratory research only.
Semax: ACTH(4-10) Heptapeptide
Semax is a synthetic heptapeptide derived from the 4-10 fragment of adrenocorticotropic hormone (ACTH). The parent ACTH(4-10) sequence is known to have neurotropic effects distinct from the steroidogenic actions of full-length ACTH. Semax modifies this fragment by adding a Pro-Gly-Pro tail at the C-terminus, which stabilises the molecule against enzymatic degradation. The compound is studied in research models of neurotrophic factor expression, with particular interest in BDNF and NGF modulation, dopaminergic and serotonergic signalling, and cerebral ischaemia tolerance.
Selank: Tuftsin-Derived Heptapeptide
Selank is a synthetic heptapeptide derived from Tuftsin, a naturally occurring tetrapeptide produced by enzymatic cleavage of IgG heavy chains in the spleen. Selank extends the Tuftsin sequence with a Pro-Gly-Pro tail similar to that used in Semax. The parent Tuftsin sequence has documented immunomodulatory and anxiolytic activity, and Selank is studied primarily in research models of anxiety, GABAergic signalling, and immune modulation. Selank has been compared in Russian preclinical literature to benzodiazepine anxiolytics, but its mechanism is non-benzodiazepine and is thought to involve modulation of GABA receptor expression rather than direct receptor binding.
Mechanistic Differences
Despite structural similarities at the C-terminus, Semax and Selank act through different primary pathways. Semax research has focused on neurotrophic factor upregulation, particularly BDNF expression in the hippocampus, and on monoamine system modulation. Selank research has focused on GABAergic and immunoregulatory effects, with reported influence on serotonergic signalling secondary to its primary mechanism. In practical research terms, Semax models examine cognitive enhancement and neuroprotection while Selank models examine anxiolytic and stress-resilience outcomes.
Research Applications
Semax has been studied in models of cerebral ischaemia, attention deficit, and cognitive performance. Selank has been studied in models of generalised anxiety, immune modulation, and stress response. The two are sometimes used in combination in research models examining cognitive performance under stress conditions, where their complementary mechanisms can be studied together.
Laboratory Handling
Both peptides are supplied as lyophilised powder. Store at -20°C prior to reconstitution. Reconstitute with bacteriostatic water by injecting slowly down the side of the vial. Both peptides are also formulated in some research settings as intranasal solutions due to good blood-brain barrier permeability, though the lyophilised research material supplied is intended for reconstitution by the researcher. Store reconstituted solutions at 2-8°C and use within 4 weeks.
Sourcing in the UK
UK Peptide Lab supplies research-grade Semax 10mg and Selank 10mg with full third-party Certificate of Analysis on every product page. Same-day UK dispatch on orders placed before 2pm GMT. For in-vitro laboratory research use only.
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Disclaimer: This article is for research and educational purposes only. All information provided is not intended as medical advice. UK Peptide Lab products are not for human consumption and are sold strictly for laboratory research use only.