Semax vs Selank: Two Russian Nootropic Peptides Compared
By Peptura Research Team/17 May 2026/7 min read
A Shared Origin Story
Semax and Selank are both synthetic heptapeptides that came out of the Institute of Molecular Genetics at the Russian Academy of Sciences from the 1980s onward. They share a comparable molecular weight and route of administration, yet they descend from completely different parent molecules and act on separate biological pathways. Russian preclinical literature classes both as nootropic research compounds. Neither is approved for clinical use in the UK by the MHRA. Semax and Selank are supplied for in-vitro laboratory research only.
Semax: Rooted in ACTH(4-10)
Semax is a synthetic heptapeptide built from the 4-10 fragment of adrenocorticotropic hormone (ACTH). That parent ACTH(4-10) sequence is known to carry neurotropic effects quite separate from the steroidogenic actions of full-length ACTH. Semax adds a Pro-Gly-Pro tail at the C-terminus to steady the molecule against enzymatic degradation. It is studied in models of neurotrophic factor expression, with particular attention to BDNF and NGF modulation, dopaminergic and serotonergic signalling, and tolerance to cerebral ischaemia.
Selank: Rooted in Tuftsin
Selank is a synthetic heptapeptide derived from Tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of IgG heavy chains in the spleen. It extends the Tuftsin sequence with a Pro-Gly-Pro tail much like the one used in Semax. Tuftsin itself has documented immunomodulatory and anxiolytic activity, and Selank is studied mainly in models of anxiety, GABAergic signalling, and immune modulation. Russian preclinical work has likened it to benzodiazepine anxiolytics, but its mechanism is non-benzodiazepine, thought to work by modulating GABA receptor expression rather than binding the receptor directly.
Where the Mechanisms Part
For all their similarity at the C-terminus, Semax and Selank run through different primary pathways. Semax research has concentrated on neurotrophic factor upregulation, particularly BDNF expression in the hippocampus, alongside monoamine system modulation. Selank research has centred on GABAergic and immunoregulatory effects, with reported serotonergic influence as a secondary consequence. In practice, 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 run together in models of cognitive performance under stress, where their complementary mechanisms can be examined side by side.
Laboratory Handling
Both come as lyophilised powder. Store at -20°C before reconstitution. Reconstitute with bacteriostatic water by running it slowly down the side of the vial. Both are sometimes formulated as intranasal solutions in research settings, given their good blood-brain-barrier permeability, though the lyophilised material supplied here is intended for the researcher to reconstitute. Keep reconstituted solutions at 2-8°C and use within four weeks.
Sourcing in the UK
Peptura 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. Peptura products are not for human consumption and are sold strictly for laboratory research use only.