Semax vs Selank
Two synthetic heptapeptides from the same research lineage, compared by mechanism, molecular profile, and the reasons they are often studied together.
Overview
Semax and Selank are both synthetic heptapeptides developed at the Institute of Molecular Genetics of the Russian Academy of Sciences, and both share the same C-terminal stabilising motif, Pro-Gly-Pro, appended to a biologically active parent sequence. That shared design is why they are frequently discussed together in the research-peptide literature.
Beyond the structural similarity they diverge: Semax is built on the ACTH(4-7) fragment and is studied chiefly for neurotrophic gene expression (BDNF/NGF) and neuroprotection, while Selank is built on the immunopeptide tuftsin and is studied chiefly for anxiolytic-type, GABAergic, and immunomodulatory endpoints.
At a Glance
| Semax | Selank | |
|---|---|---|
| Parent / origin | ACTH(4-7) core + Pro-Gly-Pro | Tuftsin (Thr-Lys-Pro-Arg) + Pro-Gly-Pro |
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Molecular weight | ~813.9 g/mol | ~751.9 g/mol |
| CAS number | 80714-61-0 | 129954-34-3 |
| Primary mechanism studied | BDNF/NGF & TrkB neurotrophic signalling | GABAergic modulation; anxiolytic-type endpoints |
| Common research focus | Cognition / focus / neuroprotection models | Anxiety-type / calm / immunomodulation models |
Semax in Brief
Semax is a synthetic ACTH(4-7)-derived heptapeptide reported to lack hormonal (corticotropic) activity. In published animal and in-vitro studies it is most associated with up-regulation of BDNF and NGF, engagement of the TrkB neurotrophic axis, and neuroprotective gene-expression effects in ischaemia models. It is the more neurotrophic, focus-oriented of the two in the research literature.
See the full Semax research guide.
Selank in Brief
Selank is a synthetic tuftsin-derived heptapeptide studied primarily for anxiolytic-type endpoints linked to GABAergic gene-expression modulation, with additional reported effects on hippocampal BDNF, serotonin metabolism, and tuftsin-derived immunomodulation. It is the more calming, anxiolytic-and-immune oriented of the two in the research literature.
See the full Selank research guide.
Key Mechanistic Differences
- Different parent molecules, different systems: Semax originates from an ACTH fragment and is studied around the neurotrophin/TrkB system; Selank originates from tuftsin and is studied around the GABAergic system and immune signalling.
- Neurotrophic vs anxiolytic emphasis: Semax's most-cited endpoints are BDNF/NGF expression and neuroprotection (e.g. Dolotov 2006; Agapova 2007); Selank's are GABAergic gene-expression modulation and anxiolytic-type behaviour (e.g. Volkova 2016).
- Immunomodulation is largely a Selank feature: Through its tuftsin lineage, Selank is reported to influence cytokine and inflammation-related gene expression (e.g. Kolomin 2011), a dimension not characteristic of Semax.
- Shared neurotrophin touch-point: Both peptides have been reported to influence hippocampal BDNF expression, one reason they appear together in combined nootropic research designs.
Why the Two Are Often Studied Together
In nootropic combination research, Semax and Selank are often paired because their primary mechanistic focuses are complementary: Semax is examined for neurotrophic, focus-type endpoints (BDNF/NGF, TrkB), while Selank is examined for anxiolytic-type, calming endpoints (GABAergic modulation). Investigators studying models that combine a focus axis with a calming axis therefore look at the two side by side. Both share the same Pro-Gly-Pro stabilising design and a common developmental origin, which makes them a natural comparison pair in the literature.
Frequently Asked Questions
What is the main difference between Semax and Selank?
They derive from different parent peptides and are studied for different mechanisms. Semax (from an ACTH fragment) is studied for neurotrophic BDNF/NGF and neuroprotection endpoints; Selank (from tuftsin) is studied for GABAergic, anxiolytic-type, and immunomodulatory endpoints.
Are Semax and Selank studied together?
Yes. In nootropic combination research they are frequently examined as a pair because their primary research focuses, neurotrophic/focus (Semax) and anxiolytic/calm (Selank), are complementary, and they share the same Pro-Gly-Pro structural motif and developmental origin.
Which one is associated with which research focus?
In the published literature, Semax is associated with cognition/focus and neuroprotection models (BDNF/NGF, TrkB), while Selank is associated with anxiety-type/calm and immunomodulation models (GABAergic modulation, cytokine gene expression). Both are supplied as lyophilised powder, ≥98% HPLC, for in-vitro laboratory research only.
Disclaimer: This information is compiled from published peer-reviewed literature and is provided for educational and research reference purposes only. It does not constitute medical advice. The peptides referenced here, sold by Enhanced Research Compounds, are intended exclusively for in-vitro research and laboratory use. They are not therapeutic goods, are not listed on the ARTG, and are not approved for human or animal consumption.