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Semax vs Selank compares two seven-amino-acid peptides with different sequences and research histories. Semax is commonly recorded as Met-Glu-His-Phe-Pro-Gly-Pro (MEHFPGP); Selank as Thr-Lys-Pro-Arg-Pro-Gly-Pro (TKPRPGP). Their shared Pro-Gly-Pro ending does not make them the same molecule.
- Both are heptapeptides, but their first four residues differ.
- Shared sequence endings do not establish identical mechanisms.
- Much of the published mechanistic literature is preclinical or region-specific.
Semax vs Selank sequence comparison
| Field | Semax | Selank |
|---|---|---|
| Length | 7 amino acids | 7 amino acids |
| Sequence | MEHFPGP | TKPRPGP |
| Research lineage | ACTH-fragment analog | Tuftsin-related synthetic peptide |
| Catalog check | Sequence, salt/form and listed mass | Sequence, salt/form and listed mass |
PubChem identity records provide a stable way to distinguish the two sequences. Published Semax studies frequently use animal ischemia or neurotrophin models. Selank papers include receptor-binding, animal and limited clinical research. Those different evidence sets should not be flattened into a single “nootropic peptide” claim.
How to compare neural peptide listings
- Start with the full seven-residue sequence.
- Record chemical form and molecular identity when supplied.
- Separate the mass per vial from the number of vials.
- Identify the experimental model behind each cited claim.
- Avoid importing a route, dose or outcome from unrelated research.
NOVABIO lists SX5 Semax and SK5 Selank within Neural & Immune Research. The product pages support catalog comparison; the linked scientific sources below support identity and evidence context.
What a responsible comparison should say
A defensible comparison can state sequence, lineage, model and measured endpoint. It should also state limitations: small studies, animal models and regional literature do not establish broad clinical efficacy. This is especially important when search results use therapeutic language that exceeds the cited evidence.
For help with abbreviations, read the NOVABIO naming guide or use the contact page.
Frequently asked questions
What is the main difference between Semax and Selank?
The clearest difference is molecular identity. Semax is the heptapeptide MEHFPGP and is related to an ACTH fragment. Selank is the heptapeptide TKPRPGP and is related to tuftsin. They share the Pro-Gly-Pro ending but have different first four residues and research histories.
Are Semax and Selank both neuropeptides?
They are commonly grouped as synthetic neuropeptides because they are studied in neurobiological contexts. The category is descriptive, not proof of equivalent action. Each compound needs its own sequence, model, endpoint and source record, and published findings should be labeled as cell, animal or human evidence.
What should a Semax or Selank catalog record include?
Include the full peptide name, seven-residue sequence, chemical form, listed mass per vial, vial count, SKU and lot documentation. A product title alone should not be used to infer purity, stability, biological activity, regulatory status or a protocol for human use.
Sources
- PubChem: Semax identity record (accessed 2026-08-27)
- PubChem: Selank identity record (accessed 2026-08-27)
- PubMed: molecular aspects of Selank (accessed 2026-08-27)
Research-use notice: This article explains catalog identity and published research. It is not medical advice, a treatment claim or a dosing guide. NOVABIO catalog products are presented for laboratory research and are not represented here as approved for human use.