Selank vs Semax — Nootropic Peptide Comparison
Two short synthetic peptides referenced in nootropic-research literature — shared design heritage, different sequences, different research contexts.
Common origins
Selank and Semax are both short synthetic peptides developed in Russian research programmes and referenced in nootropic-research literature. They share design heritage in the use of short, stabilised amino-acid sequences with central-nervous-system relevance.
Where they diverge
The two compounds differ in sequence, receptor engagement, and the research contexts in which they're commonly examined. Selank is more often referenced in anxiolytic and immunomodulatory research; Semax is more often referenced in neuroprotection and cognitive contexts. Their parent molecules differ too — the entries record distinct derivations rather than a shared one.
Side by side, from the catalog
| Specification | Selank | Semax |
|---|---|---|
| Compound class | Synthetic heptapeptide (tuftsin analog) | Synthetic ACTH(4-10) analog (heptapeptide) |
| Length (aa) | 7 | 7 |
| Molecular weight | 751.9 g/mol | 813.9 g/mol |
| Reported half-life | ~2-30 minutes (plasma; short, effects outlast) | ~2-5 minutes (plasma) |
A cell reading "Not listed" is a gap in the published record. PeptiDex records a specification only where a source documents it, and never substitutes an estimate.
Stated mechanisms
Selank — Selank is a stabilized analog of tuftsin (a fragment of the immunoglobulin G heavy chain) and is reported to exert anxiolytic and immunomodulatory effects.
Semax — Semax is an analog of the ACTH(4-10) melanocortin fragment but is described as being devoid of hormonal (corticotropic) activity.
What each entry's record says separates it
- Selank — Unlike Semax (an ACTH fragment focused on neuroprotection and cognition), Selank derives from tuftsin and is primarily positioned as an anxiolytic with immunomodulatory activity.
- Semax — Semax is a melanocortin (ACTH)-derived peptide oriented toward neuroprotection and cognition, whereas Selank derives from tuftsin and is oriented toward anxiolysis.
Both entries also record a plasma half-life measured in minutes alongside research contexts described over much longer windows. That mismatch is a documented feature of this literature rather than a contradiction in the records, and it is one of the reasons the two are usually discussed together.
Cross-references
- Selank — full research overview and specifications.
- Semax — full research overview and specifications.
- Nootropic & CNS hub — the whole category, compared side by side.
- Compare Peptides — put both entries next to each other on the full specification set.