Cognitive Peptides — Nootropics Reference Comparison
Semax (BDNF onset 15–20 min, PMID 18457799), Selank (GABA-A anxiolytic, PMID 19827524), Dihexa (~10M× BDNF potency, PMID 24726369, rodent only), Humanin (mitochondrial-derived, PMID 27151978).
| Measure | Value | Unit | Notes |
|---|---|---|---|
| Peptides Compared | 5 | compounds | Selank, Semax, Dihexa, Humanin, BPC-157 — spanning anxiolytic to synaptogenic to mitochondrial mechanisms |
| Selank Evidence Grade | B/C | grade | Grade B Russian clinical (licensed); Grade C Western peer-review; anxiolytic/GABA-A mechanism |
| Semax Evidence Grade | B/C | grade | Grade B Russian clinical (licensed for stroke); Grade C Western; BDNF upregulation mechanism |
| Dihexa Evidence Grade | D | grade | Rodent/in vitro only; no human trials; extreme potency claims not validated in humans |
| Humanin Evidence Grade | C | grade | Grade C — animal models and observational human data; no RCTs; endogenous mitochondrial peptide |
| BPC-157 Cognitive Evidence | C | grade | Indirect neuroprotection via anti-inflammatory and growth factor pathways; primary evidence is for tissue repair |
Cognitive Peptides — Overview
Peptides with cognitive or neuroprotective effects span several distinct mechanistic categories: anxiolytics (Selank), neurotrophic activators (Semax), synaptogenic compounds (Dihexa), endogenous neuroprotective peptides (Humanin), and indirect neuroprotectors via anti-inflammatory pathways (BPC-157). This page is a reference comparison for these five compounds.
Primary Comparison Table
| Peptide | Primary Mechanism | Cognitive Target | Evidence Grade | Legal Status (USA) | Route | Human Data? |
|---|---|---|---|---|---|---|
| Selank | GABA-A modulation | Anxiety reduction; mood stabilization | B (Russian), C (Western) | Research chemical | Intranasal | Limited (Russian clinical) |
| Semax | BDNF upregulation via MC4R | Focus; neuroprotection; post-stroke | B (Russian), C (Western) | Research chemical | Intranasal | Russian clinical (licensed) |
| Dihexa | HGF/MET agonism | Synaptogenesis; memory consolidation | D | Research chemical | SC (research only) | None |
| Humanin | Mitochondrial-derived cytoprotection | Neuroprotection; AD models | C | Research chemical | SC (research) | Observational only |
| BPC-157 | Growth factor upregulation; anti-inflammatory | Indirect neuroprotection | C (neuroprotection) | Research chemical | SC or oral | No robust human data |
Mechanism Detail Table
| Peptide | Receptor/Target | Upstream Pathway | Downstream Effect | Onset (rodent) |
|---|---|---|---|---|
| Selank | GABA-A receptor | GABA enhancement | Anxiolytic; serotonin modulation | 30–60 min |
| Semax | MC4R (melanocortin) → CREB | cAMP/CREB signaling | BDNF ↑; cholinergic modulation | 15–20 min (BDNF) |
| Dihexa | c-MET (HGF receptor) | HGF/MET → PI3K/Akt | Synaptogenesis; dendritic branching | Days (persistent) |
| Humanin | IL-6 receptor family; IGF-1R | JAK/STAT; PI3K/Akt | Anti-apoptotic; neuroprotection | Unknown (endogenous) |
| BPC-157 | VEGFR; EGF; dopamine D1/D2 | Multiple growth factor pathways | Anti-inflammatory; tissue repair | 1–4 hours (rodent) |
Evidence Depth Table
| Peptide | Rodent Evidence | Human Observational | Human RCT | Approved Use |
|---|---|---|---|---|
| Selank | Yes — monoamine modulation (PMID 19827524) | Russian clinical reports | No Western RCT | Russia (anxiolytic) |
| Semax | Yes — BDNF (PMID 18457799, 24307957) | Russian clinical (stroke) | No Western RCT | Russia (stroke/TIA) |
| Dihexa | Yes — synaptogenesis, memory (PMID 24726369) | None | None | None |
| Humanin | Yes — neuroprotection, AD models | Yes — age-related decline (PMID 27151978) | None | None |
| BPC-157 | Extensive — gut, tendons, CNS indirect | Anecdotal; case reports | None | None |
Legal Status Table
| Peptide | USA | UK | Australia | Canada | EU |
|---|---|---|---|---|---|
| Selank | Research chemical | Not scheduled | Gray area | Gray market | Not harmonized |
| Semax | Research chemical | Not scheduled | Gray area | Gray market | Not harmonized |
| Dihexa | Research chemical | Not scheduled | Gray area | Gray market | Not harmonized |
| Humanin | Research chemical | Not scheduled | Not listed | Not listed | Not harmonized |
| BPC-157 | Research chemical | Not scheduled | Not listed | Not listed | Not harmonized |
Evidence Grade Callout
Grade B/C (Selank, Semax): Russian clinical licensing represents real regulatory approval, but evidence does not meet Western peer-review standards for independent confirmation. Grade C is the appropriate rating for Western evidence-based practice. Grade C (Humanin, BPC-157 neuroprotection): Animal model and observational data; no human RCTs for cognitive endpoints. Grade D (Dihexa): No human data of any kind. Preclinical potency is extraordinary but entirely unvalidated in humans and carries unknown risk.
Legal Disclaimer
None of the peptides on this page is FDA, EMA, TGA, or Health Canada approved for cognitive enhancement. All are research chemicals outside their specific licensed jurisdictions (Selank and Semax in Russia only). Human use outside registered clinical trials is unsupported by Western regulatory frameworks. This page is educational and does not constitute medical advice.
Related Pages
Sources
- Agapova TY et al. Effects of Semax on the BDNF system in rat brain. Bull Exp Biol Med. 2007;144(5):636-40. PMID 18457799
- Semenova TP et al. Effects of Selank on monoamine metabolism in rats. Zh Vyssh Nerv Deiat. 2009;59(4):469-76. PMID 19827524
- Bhattarai JP et al. Dihexa facilitates conditioned fear responses via HGF/c-Met system. J Cogn Neurosci. 2014;26(8):1925-36. PMID 24726369
Frequently Asked Questions
What is the best-evidenced cognitive peptide?
By Western peer-review standards, no peptide meets Grade A (RCT) evidence for cognitive enhancement in healthy adults. Semax has the most mechanistically characterized profile — BDNF upregulation within 15–20 minutes (PMID 18457799) and Russian-licensed clinical use for post-stroke cognitive recovery — making it Grade B by Russian standards and Grade C by Western standards. Selank is well-characterized for anxiolytic effects (Grade B Russian, Grade C Western). Dihexa has impressive rodent data but zero human trials (Grade D).
Does BPC-157 have nootropic effects?
BPC-157's primary evidence base is for tissue repair (tendons, gut lining, musculoskeletal injury). However, BPC-157 has demonstrated indirect neuroprotective effects in rodent models via dopaminergic system modulation and anti-inflammatory pathways. It is not primarily classified as a cognitive enhancer, but the reduction of neuroinflammation may provide indirect cognitive benefit in individuals with inflammatory or injury-related cognitive impairment. Evidence for direct cognitive enhancement in healthy subjects is Grade D.
Is Humanin a peptide?
Yes. Humanin is a 21 amino acid mitochondrial-derived peptide (MDP) encoded by the 16S rRNA region of the mitochondrial genome. It represents a class of small peptides produced by mitochondria that act as cytoprotective and neuroprotective signaling molecules. Humanin levels decline approximately 30% per decade after age 40 in humans (Cobb et al. 2016, PMID 27151978), correlating with aging-related neurodegeneration risk. It is not administered exogenously with any established protocol — research is in observational and animal stages.