Tuftsin, ACTH and the Soviet nootropic school — how Selank and Semax came to be
In the 1980s, a Moscow research group modified two endogenous peptide sequences — tuftsin and an ACTH fragment — by C-terminal tetrapeptide extensions into more stable analogs: Selank and Semax. From the research institutes of the late Soviet Union came substances that today are approved in Russia and circulate in the West as research chemicals.
The approach: endogenous sequences, half-life stabilised
In the early 1980s, a systematic strategy was pursued at the Institute of Molecular Genetics of the Soviet Academy of Sciences in Moscow: to extend endogenous peptide sequences with short pharmacokinetic half-lives by C-terminal modifications into clinically usable analogs. The specific modification used repeatedly was a C-terminal tetrapeptide Pro-Gly-Pro (PGP) that is more resistant to enzymatic degradation than the original C-terminus of the native peptide.
Two application lines emerged from this strategy. Semax is an N-terminal tetrapeptide sequence of adrenocorticotropic hormone (ACTH 4-7: Met-Glu-His-Phe) with an appended Pro-Gly-Pro: Met-Glu-His-Phe-Pro-Gly-Pro. Selank is a modification of the endogenous tetrapeptide tuftsin (Thr-Lys-Pro-Arg) with the same C-terminal Pro-Gly-Pro: Thr-Lys-Pro-Arg-Pro-Gly-Pro.
Semax and stroke
The original hypothesis behind Semax stems from animal neurology of the 1980s-90s: the ACTH 4-10 fragment had been described as nootropically active since the 1970s, but with short half-lives and unclear clinical utility. Semax extended plasma stability and enabled intranasal administration. In Russian clinical trials of the 1990s and 2000s, Semax was used for acute ischaemic stroke, cognitive sequelae and ADHD. Several Russian phase 3 trials were published; the substance received Russian medicines approval in 1994 and is on the Russian list of vital medicines.
Methodologically, reported effect sizes in acute stroke trials are moderate — comparable with other neuroprotectives such as cerebrolysin or citicoline used in the Russian care setting. A Western ICH-GCP-compliant replication or inclusion in international stroke guidelines (AHA, ESO) has not taken place; the substance is not approved outside Russia.
Selank and anxiolysis
Selank was developed from the late 1990s as an anxiolytic peptide and approved in Russia in 2009 for generalised anxiety disorder. Tuftsin itself had originally been characterised as an immune-modulating peptide (Najjar & Nishioka, 1970); its CNS action via GABAergic, serotonergic and modulation of enkephalin levels was described later. Selank shows anxiolytic effects in Russian clinical trials without typical benzodiazepine side effects (sedation, tolerance, dependence). These findings are consistently documented in Russian-language literature but practically not replicated in Western original research.
A small number of preclinical studies from Western laboratories have confirmed individual effects (modulation of enkephalinase, changes in gene expression of neurotrophic factors in rodent models). These replications concern individual mechanistic observations, not clinical benefit in human anxiety disorders.
„We developed in the 1980s a methodology that stabilises short regulatory peptides. The question is not whether the substances work — Russian clinical practice has used them for decades — but whether Western research is willing to do its own replications."
International diffusion as a nootropic
From the 2010s, Selank and Semax were discovered in English-language nootropic and bio-hacking communities. They became available through Russian pharmacy imports and research-chemical vendors. User reports predominantly concern cognitive and mood-modulating effects: improved concentration, reduced stress, focused sleep with chronic use. These reports are subjective and not systematically collected.
The legal situation is clear: Selank and Semax are approved medicines in Russia, not approved in the EU and the US. Imports for personal use are not legally covered in most Western jurisdictions.
What this line methodologically shows
The Selank/Semax story shares with the Khavinson line a central structure: a self-contained research tradition that has been productive for decades, built a clinical apparatus in its own jurisdiction, and whose central claims have not been systematically replicated outside that ecosystem. This is not a statement about biological plausibility — the Pro-Gly-Pro modification as a pharmacokinetic strategy is mechanistically understandable — but about the methodology of international knowledge transfer.
For assessing the substances this means: 'approved in Russia' is a fact with clinical significance in its jurisdiction. 'Effective in the West' is a statement not yet sufficiently supported by independent RCTs. Both statements can be true simultaneously without yielding a clinical-use consensus.
Open questions
- Which of the documented clinical effects (acute stroke for Semax, GAD for Selank) would be realistically fundable for a Western RCT replication?
- What pharmacokinetic data on intranasal vs. parenteral administration exist in accepted form?
- How have use reports in English-language communities changed since 2022, when Russian sources became harder to access?
- Can the Pro-Gly-Pro stabilisation strategy be transferred to further short regulatory peptides — and who would try it systematically?