P21 is a synthetic peptide derived from the active region of Ciliary Neurotrophic Factor (CNTF) that promotes hippocampal neurogenesis without the immunogenic side effects of full-length CNTF. It was developed to cross the blood-brain barrier and stimulate brain-derived neurotrophic factor (BDNF) release. Preclinical studies in Alzheimer's disease mouse models showed improved spatial memory and increased neurogenesis. It has become popular in the nootropics community but lacks human clinical data.
Category: Nootropic / Neurogenesis. Evidence rating: D (animal/preclinical only).
Clinical status: Preclinical only. No human clinical trials. Studied in Alzheimer's mouse models.
P21 is a modified tetrapeptide (Ac-DGGL-OH) linked to adamantane to enhance blood-brain barrier penetration. It mimics CNTF's neurotrophic activity by stimulating BDNF release and promoting the proliferation and differentiation of neural progenitor cells in the hippocampal dentate gyrus. Unlike…
Safety considerations: No human safety data available; Preclinical studies reported no significant adverse effects at studied doses in rodents; Designed to avoid the immunogenicity (antibody formation) problems of full-length CNTF.
Reviewed by the PeptideAtlas Editorial Team.
| Production method | synthetic |
|---|---|
| Anti-doping status | not-listed |
| US regulatory status | Not FDA-approved. Research compound only. |
In research, P21 was administered via intraperitoneal injection in rodents. In nootropic communities, intranasal and subcutaneous routes are discussed anecdotally. No human pharmacokinetic data exists for any route.
P21 was developed as a defined synthetic alternative to Cerebrolysin, which is a complex mixture of neurotrophic peptides derived from pig brain. P21 targets the same CNTF-mediated pathways but as a single defined compound.
P21 has shown promise in Alzheimer's mouse models, but no human clinical trials have been conducted. Mouse models of Alzheimer's are notoriously poor predictors of human efficacy.
None. All studies used disease models (aged rats, Alzheimer's mice). There is no evidence that P21 enhances cognition in healthy individuals.