P21
A CNTF-derived research peptide (Institute for Basic Research, New York) that crosses the blood-brain barrier and stimulates hippocampal neurogenesis in rodent models of Alzheimer disease, Down syndrome, and aging. Not FDA-approved; not commercially marketed; research-only with no human trials to date.
A peptidomimetic derived from a 21-amino-acid region of the human ciliary neurotrophic factor (CNTF) D1 domain. Developed by Iqbal and colleagues at the New York State Institute for Basic Research in Developmental Disabilities as a small neurotrophic peptide candidate for age-related cognitive decline, Alzheimer disease, and Down syndrome; shown in rodent studies to enhance adult hippocampal neurogenesis, reduce tau phosphorylation, and improve spatial learning. No human clinical data; peptide remains a research tool.
Mechanism of action
Reported to bind the leukemia inhibitory factor receptor beta (LIFRβ) / gp130 complex — the shared CNTF signaling receptor — activating downstream JAK/STAT3 and MAPK signaling associated with neuronal survival and adult hippocampal neurogenesis. In rodent models, P21 has been reported to reduce tau hyperphosphorylation, improve hippocampal-dependent memory performance, and reverse cognitive deficits in APP/PS1 and 3xTg-AD Alzheimer models. Mechanism remains incompletely characterized and receptor binding data are derived from a small number of preclinical reports from a single research group.
Primary uses
- Cognitive enhancement research (preclinical only)
- Alzheimer disease model studies (rodent)
- Down syndrome cognitive deficit models (rodent)
Typical dosing
⚠ No human dosing has been established. Rodent studies have used 25–500 μg/kg ranges. Any human use would be entirely off-label, unapproved, and unsupported by any clinical evidence.
Educational information, not medical advice. The doses on this page come from approved labels, published studies and, where no study exists, amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
Regulatory status
Not FDA-approved. No human clinical trials registered on ClinicalTrials.gov. Sold informally in the research-chemical / nootropic grey market, often mislabeled or with questionable provenance. Any human use would be unapproved and unregulated.
Status as of this entry's last review, April 19, 2026. Approvals, compounding rules and sport rules change; the regulatory tracker is checked more often.
What we checked
P21 here means the CNTF-derived neurogenic peptide from the New York State Institute for Basic Research, also written P021, not the cell-cycle protein p21. Its studies are in rodents; this section records what can be checked.
Identity, computed
| Sequence | Not established |
The dataset describes an acetylated, amidated hexapeptide core built around an adamantylglycine, a non-standard residue the site's calculator does not model, so no formula or mass is computed here.
Regulatory status, read October 5, 2026
Drugs@FDA: 0 records for “P021”. EMA medicines list: 0 records for “P021”. Run for semaglutide, the same queries return 6 and 5 records (and the registry search 84 trials), so a zero here is an absence, not a broken search. Not named on the WADA 2026 and 2027 Prohibited Lists. As a substance with no current approval for human therapeutic use, it falls under section S0 (non-approved substances), which is prohibited at all times; the lists were read on September 27, 2026.
What the maker or sellers claim
Claim, from research-chemical sellers: P21 grows new brain cells and treats or prevents Alzheimer's disease in people. Its studies are in rats and mice.
About CNTF, the protein it comes from
Ciliary neurotrophic factor (CNTF) supports nerve cells. The developers' rodent studies, cited in References, report that a small CNTF-derived peptide given by mouth increased hippocampal neurogenesis and improved memory in Alzheimer and ageing models.
What we looked for and did not find
No human study, no registry record and no dose from a controlled human study. Searches for 'P21' return thousands of papers about the unrelated cell-cycle protein p21 (CDKN1A).
| Source | Query | Results, October 5, 2026 | What it was |
|---|---|---|---|
| PubMed | P021 neurogenesis | 9 | the developers' name for the peptide |
| PubMed | CNTF peptide P021 Alzheimer | 8 | the rodent studies |
| ClinicalTrials.gov | P021 | 0 | |
| Drugs@FDA (openFDA) | P021 | 0 | |
| EMA medicines list | P021 | 0 |
References
- [pubmed] Bolognin S, et al. "An experimental rat model of sporadic Alzheimer's disease and rescue of cognitive impairment with a neurotrophic peptide." Acta Neuropathol, 2012;123(1):133-51. PMID: 22083255.
- [pubmed] Kazim SF, et al. "Disease modifying effect of chronic oral treatment with a neurotrophic peptidergic compound in a triple transgenic mouse model of Alzheimer's disease." Neurobiol Dis, 2014;71:110-130. PMID: 25046994.
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Guides & tools
This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.