Source comparison
Selank vs Semax: Two Russian Peptides, Constantly Confused
Selank and Semax are frequently discussed together, sold together, and conflated. They share a developmental origin, a design philosophy and a route — and almost nothing else. In particular they have different parent molecules and different proposed targets: S
This comparison does not assign a generated winner or score.
- Selank and Semax are frequently discussed together, sold together, and conflated. They share a developmental origin, a design philosophy and a route — and almost nothing else. In particular they have different parent molecules and different proposed targets: Selank is a tuftsin analogue framed as an anxiolytic; Semax is an ACTH(4-10) analogue framed as a nootropic and neuroprotective agent.
- Parent molecule
- Tuftsin, Thr-Lys-Pro-Arg (an immunopeptide from IgG)
- ACTH(4-10), a fragment of adrenocorticotropic hormone
- Sequence
- Thr-Lys-Pro-Arg-Pro-Gly-Pro
- Met-Glu-His-Phe-Pro-Gly-Pro
- Shared design element
- Both append the stabilising tripeptide Pro-Gly-Pro to a bioactive parent fragment
- Framing in the literature
- Anxiolytic
- Nootropic / neuroprotective; investigated in cerebral ischemia models[15]
- Canonical route
- Intranasal
- FDA/EMA status
- Neither
- Shared finding
- Both inhibit enkephalin-degrading enzymes from human serum in vitro (Selank IC50 ≈ 20 µM; Semax ≈ 10 µM)[13]
- The practical consequence: do not transfer a Semax number to Selank or vice versa. Different parent molecules, different proposed targets, different registered concentrations. The Pro-Gly-Pro tail they share is a stability motif, not a functional equivalence. Interestingly, PGP has itself been examined in the ischemia transcription literature, where Dmitrieva and colleagues reported that its influence on neurotrophin and receptor gene transcription was largely non-specific, in contrast to Semax, which selectively affected transcription[15]. That finding cuts against, rather than for, the idea that the shared tail explains either compound’s activity — which is a useful reminder that the two molecules are related by construction technique, not by pharmacology. Anyone considering how compounds get combined should read the guide to stacking peptides, which is explicit about how little combination evidence exists for most of this category.