Semax vs Selank: How Two Related Neuropeptides Differ
Semax and Selank came out of the same Russian neuropeptide research program, share a design trick and are often mentioned together. But they start from different natural peptides and are studied for different things. This guide compares them so you can choose the right one, or design a study that uses both.
At a glance
| Semax | Selank | |
|---|---|---|
| Based on | ACTH(4–7), a fragment of adrenocorticotropic hormone | Tuftsin, an immunomodulatory tetrapeptide |
| Length | Heptapeptide (7 residues) | Heptapeptide (7 residues) |
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Stabilizing extension | C-terminal Pro-Gly-Pro | C-terminal Pro-Gly-Pro |
| Main research areas | BDNF expression, neurotrophic signaling, neuroprotection models | GABAergic signaling, anxiety-related behavioral models, immune cytokines |
The shared design: Pro-Gly-Pro
Short natural peptides are broken down quickly by enzymes. Both Semax and Selank add the tripeptide Pro-Gly-Pro to the end of their parent sequence, which makes them more resistant to enzymatic breakdown and extends their activity in research models. This shared design, and a shared origin, is why they are so often studied together.
Semax: from a stress-hormone fragment
Semax starts from ACTH(4–7), a short piece of adrenocorticotropic hormone that keeps some of ACTH’s activity in the nervous system without its hormonal effects on the adrenal glands. Research has focused on its association with brain-derived neurotrophic factor (BDNF) and other neurotrophic signals, and on neuroprotection models. See the Semax research profile.
Selank: from an immune peptide
Selank starts from tuftsin, a natural tetrapeptide involved in immune function. Its research profile is different from Semax’s: studies have examined its effects on GABAergic signaling, anxiety-related behavior in animal models, the enzymes that break down enkephalins, and immune-cytokine expression. See the Selank research profile.
Choosing between them
Neurotrophic, BDNF or neuroprotection research: Semax.
GABAergic, stress-behavior or neuro-immune research: Selank.
Comparing two stabilized neuropeptides from the same family: both, side by side, which separates the effects of the parent sequence from the shared Pro-Gly-Pro design.
Related neuropeptides
Researchers working in this area often also look at DSIP (delta sleep-inducing peptide), studied in sleep-architecture and neuroendocrine models. All three sit in our neuropeptide and melanocortin collection.
Handling and testing
Both are supplied as lyophilized powder. Store sealed vials at -20°C away from light, and see our storage guide for solutions. Every lot is tested by Bioviridian Labs (ISO/IEC 17025, Texas) for HPLC purity, mass-spectrometry identity, endotoxin and heavy metals. Look up any lot in the COA Library.
For laboratory research use only. Not for human or veterinary use. This article summarizes published research for educational purposes and does not provide medical advice.