P21
Research OnlyA hexapeptide (Ac-DGGLAG-NH2) derived from ciliary neurotrophic factor (CNTF) that is claimed to mimic BDNF effects and promote neurogenesis. Developed primarily at the New York State Institute for Basic Research. Limited to preclinical rodent studies with no human clinical trials. Sold as a research chemical with unknown safety profile.
Ac-DGGLAG-NH2 · P021 · CNTF-derived peptide
Preclinical evidence only
- Preclinical
- 100%
- Clinical
- 0%
Based on 15 cited sources
Demonstrated effect magnitude — not a recommendation or safety claim.
Research Depth 12: animal data only, no human studies (1A 6); no RCTs so risk-of-bias and precision elements floor (1B 0, 1C 0); evidence indirect to human use (1D 0); substantial multi-study preclinical program across normal mice, aged F344 rats and 3xTg-AD mice but from essentially one group, no independent replication (1E 6) — Li 2010 (PMID:20600002), Kazim 2014 (PMID:25046994), Bolognin 2014 (PMID:24702821), Baazaoui 2017 (PMID:28655344). Mechanism 43: P21's own molecular target/receptor is inferred (BDNF-mimetic via LIF inhibition) with no binding affinity and not validated at the receptor level (2A 10); downstream LIF->BDNF->TrkB->PI3K/ Akt->GSK-3beta->tau chain mostly mapped to the proximal effect (2B 16); limited dose-response (2C 8); confirmed in in-vivo mammalian models (2D 9). Plausibility 66: mechanism->surrogate (neurogenesis, BDNF, synaptic markers, tau) established in animals with clinical benefit inferred only (3A 24); coherent with neurotrophic/neurogenesis biology and AD pathophysiology (3B 20); analogous neurotrophic-mimetic class support (3C 12); moderately broad multi-target claim, mechanism-consistent (3D 10). Global Coverage 22: primary efficacy work confined to the Iqbal/IBR group with limited cross-institutional spread (one Finland CRO, a MUSC imaging collaboration still co-authored by Iqbal) (4A 6, 4B 7); ~15 studies of moderate diversity (4C 9); no governance review anywhere, research-only (4D 0). Community Experience 27: niche but persistent research-chemical discussion (5A 8), short track record (5B 8), sparse/inconsistent reports with empty positive and negative arrays (5C 5), no notable adverse signal over very low exposure (5D 6). Effectiveness not-established: zero human efficacy data and no meaningful community effect signal (empty report arrays), so no score is assigned.
The proposed mechanisms of P21 are based entirely on animal and in vitro studies. No human mechanistic data exists.
How It Works (Simplified)
P21 is designed to bypass the blood-brain barrier and activate neurotrophic signaling:
Increases brain-derived neurotrophic factor expression by inhibiting leukemia inhibitory factor (LIF) signaling pathway.
Promotes formation of new neurons in dentate gyrus through enhanced proliferation and maturation of neural progenitor cells.
Via BDNF/TrkB/PI3K/Akt pathway, inhibits GSK-3beta activity - reducing abnormal tau hyperphosphorylation.
Restores synaptic proteins (PSD-95, synapsin-1) and glutamate receptors supporting plasticity and memory.
Key Research: Li B et al. (2010) demonstrated neurogenesis enhancement in normal mice. PMID:20600002
Important Limitations
- All studies from a single research group (Iqbal laboratory at IBR)
- No independent replication of key findings
- Translation to human physiology is completely unknown
- No human pharmacokinetics or safety data
- 15+ years of research with no clinical trial advancement
- “BDNF-mimetic” claim not fully validated at receptor level
Based on preclinical observations: Initial BDNF pathway activation may begin. Animal studies show early changes in CREB phosphorylation and neurotrophin signaling within days. No human timeline data available.
PMID:20600002Animal studies suggest neural progenitor proliferation increases. In mouse models, Ki-67+ cells (proliferating) and DCX+ cells (immature neurons) show measurable increases by 2-4 weeks of treatment.
PMID:25046994Preclinical models show continued neurogenesis and early synaptic protein restoration. Tau phosphorylation changes and GSK-3beta inhibition effects observed in AD mouse models within this timeframe.
PMID:27400746Long-term animal studies (3-12 months) suggest sustained cognitive improvements and ongoing neuroprotection. However, human pharmacokinetics, optimal dosing, and treatment duration are completely unknown.
PMID:28655344Research-based observations
This timeline reflects observations from published clinical and preclinical studies. Individual responses may vary significantly. This is not a guarantee of effects or a dosing schedule. Consult qualified healthcare providers for personalized guidance.
Good Signs (7 indicators)
Warning Signs (6 indicators)
Bad Signs (7 indicators)
For Research Evaluation Only
These quality indicators are general guidelines based on typical peptide characteristics. Professional laboratory testing (HPLC, mass spectrometry) provides definitive quality verification. This checklist is for initial visual evaluation only.
Dihexa
CompatibleBoth target cognitive enhancement through different mechanisms. P21 focuses on BDNF/neurogenesis while Dihexa acts on HGF/c-Met pathway. No interaction studies available; theoretical complementary nootropic effects.
Semax
CompatibleDifferent neurotrophic mechanisms. P21 is CNTF-derived targeting BDNF while Semax is ACTH-derived with broader neuroprotective effects. No known contraindications; both aim to support cognitive function.
Cerebrolysin
CompatibleCerebrolysin is a complex peptide mixture with neurotrophic properties. P21 has a more targeted mechanism via BDNF pathway. No interaction data available; both target neuroregeneration.
Selank
CompatibleNon-overlapping mechanisms. P21 targets neurogenesis while Selank modulates anxiety and immune function. Theoretical complementary cognitive benefits.
BPC-157
CautionBoth have neuroprotective claims but through different pathways. BPC-157 affects dopaminergic system while P21 targets BDNF/LIF signaling. Limited data on CNS interactions; exercise caution.
Research Note: Interaction data is based on published literature, mechanistic understanding, and theoretical considerations. Most peptide combinations lack direct clinical study. This information is for educational purposes only and does not constitute medical advice. Always consult qualified healthcare providers.
Key Studies Cited
Full reference list available on request. All citations link to PubMed for verification.
This dossier synthesizes available evidence from peer-reviewed literature, regulatory documents, and clinical trial registries. Evidence strength ratings follow a modified GRADE approach.
For complete methodology details, see our Methodology page.
Important Disclaimer
This dossier is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before making health decisions.
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