FOR LABORATORY RESEARCH USE ONLY — not for human or veterinary use, diagnosis, treatment, or cosmetic application. Buyers must be 21+ and legally permitted to purchase research chemicals in their jurisdiction.Intended-use statement →
Selank vs Semax
Both are synthetic heptapeptides carrying a Pro-Gly-Pro C-terminal extension, and both are widely described as nootropic-adjacent research peptides. Their precursors are unrelated, their literature streams are different, and the shared C-terminal motif is a stabilisation device rather than evidence of interchangeable pharmacology.
Side-by-side comparison
| Parameter | Selank | Semax |
|---|---|---|
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Met-Glu-His-Phe-Pro-Gly-Pro |
| Precursor | Tuftsin (Thr-Lys-Pro-Arg), an immunoglobulin G heavy-chain fragment | ACTH(4-7) (Met-Glu-His-Phe), the CNS-directed fragment of ACTH |
| Shared feature | C-terminal Pro-Gly-Pro extension | C-terminal Pro-Gly-Pro extension |
| Why the extension is there | Introduced to increase resistance to peptidases and extend duration of action | Attached to protect the ACTH(4-7) core from peptidase hydrolysis |
| Dominant research streams | GABA-related cell experiments; enkephalin-degradation assays; BDNF expression in rat hippocampus | Bdnf/Ngf and TrkB expression in cell and rat hippocampus models; neuroprotection endpoints |
| Human data measured | A 52-participant imaging study reported short-term resting-state connectivity changes (5 and 20 min after administration) | Same imaging design included Semax; clinical reports concern stroke-rehabilitation populations |
| What the data do not show | Anxiolytic or cognitive benefit in healthy users | Focus or cognitive benefit in healthy users |
Sequences and stabilisation rationale: published reviews of Semax and Selank (Russian regulatory-peptide literature). Human imaging endpoints: Panikratova et al., Doklady Biological Sciences 490:9-11 (2020), DOI 10.1134/s001249662001007x, 52 healthy participants. Rates and potencies are not compared because none are published as head-to-head human outcomes.
How to choose between them
Match the peptide to the pathway you are measuring
If your readouts are neurotrophin transcription (Bdnf, Ngf, TrkB), Semax is the peptide with that literature. If your readouts are GABA-related gene expression or enkephalin-degrading enzyme activity, use Selank.
Do not treat the shared tail as a shared mechanism
The Pro-Gly-Pro trio appears in both molecules because it improves metabolic stability. It is a scaffold modification, not a pharmacophore that makes the peptides equivalent.
Read human studies by endpoint, not by headline
The largest controlled human comparison measured resting-state functional connectivity in 52 healthy participants at 5 and 20 minutes. Connectivity changes are not cognitive or anxiolytic outcomes, and no such benefit should be inferred.
Products in this comparison
| Product | List price (per kit of 10 vials) |
|---|---|
| Selank | US$45–64 per kit (10 vials), from our published wholesale price list; tiered volume discounts apply (see the tier table) |
| Semax | US$45–58 per kit (10 vials), from our published wholesale price list; tiered volume discounts apply (see the tier table) |
| Epithalon | US$64–185 per kit (10 vials), from our published wholesale price list; tiered volume discounts apply (see the tier table) |
| DSIP | US$40–93 per kit (10 vials), from our published wholesale price list; tiered volume discounts apply (see the tier table) |
| Pinealon | US$42–93 per kit (10 vials), from our published wholesale price list; tiered volume discounts apply (see the tier table) |
FAQ
Are Selank and Semax the same molecule with different names?
No. Selank is H-Thr-Lys-Pro-Arg-Pro-Gly-Pro-OH, derived from tuftsin; Semax is H-Met-Glu-His-Phe-Pro-Gly-Pro-OH, derived from the ACTH(4-7) fragment. They share only the C-terminal Pro-Gly-Pro stabilisation motif.
Why do both molecules end in Pro-Gly-Pro?
Because that tripeptide increases resistance to peptidase hydrolysis, extending the useful lifetime of a short peptide. The same stabilisation strategy was applied to two unrelated lead sequences.
What neurotrophin effects are reported for Semax?
Cell and animal studies report increased transcription of Bdnf and Ngf (approximately 8-fold and 5-fold in glial cell culture) and raised Bdnf/TrkB mRNA in rat hippocampus. These are model-system findings, not clinical outcomes.
Are human-use or dosing instructions available?
No. Both products are supplied FOR LABORATORY RESEARCH USE ONLY. We provide no dosing, administration or application information of any kind, and no human or veterinary application is claimed or implied.
Need a quote for this group?
Component specifications, batch COAs and volume pricing for the whole cluster — quoted within one business day.