Dihexa
Low EvidenceA hexapeptide analog studied for cognitive enhancement via hepatocyte growth factor pathway activation.
What It Is
Dihexa (N-hexanoic-Tyr-Ile-(6) aminohexanoic amide) is a synthetic hexapeptide analog derived from angiotensin IV, originally developed at Washington State University. It is one of the most potent synaptogenic compounds identified in preclinical research, with studies showing synaptogenesis amplification rates seven times greater than brain-derived neurotrophic factor (BDNF) alone. Unlike conventional nootropics that modulate neurotransmitter availability, dihexa binds to hepatocyte growth factor (HGF) receptors and activates the c-Met/PI3K/AKT signaling pathway, triggering structural changes in dendritic spine density that can persist weeks after administration stops. A 2021 study in APP/PS1 Alzheimer's model mice demonstrated that dihexa rescued cognitive impairment and recovered memory function via PI3K/AKT signaling. A 2026 study from the University of Toronto's Cognitive Neuroscience Lab, published in Neuropsychopharmacology, reported that dihexa administration at 5 mg/kg in non-human primates produced measurable increases in dendritic spine density within 14 days. Dihexa is notable for its oral bioavailability and exceptional blood-brain barrier permeability, properties uncommon among peptide compounds. As of April 2026, the FDA removed dihexa from the Category 2 bulk substances list, and it will be reviewed by the PCAC. Despite growing interest in cognitive enhancement applications, no FDA-approved human clinical trials are actively recruiting. The involvement of the HGF/c-Met pathway — which also plays a role in tumor growth and metastasis — remains a theoretical safety concern that has slowed clinical translation.
Regulatory Status
Removed from Category 2 in the FDA's April 2026 reclassification. Dihexa is in the second PCAC session group (alongside LL-37, GHK-Cu injectable, PEG-MGF, and Melanotan II) scheduled before February 2027. No FDA-approved human clinical trials actively recruiting.
Effective: April 2026
View FDA SourceWhy Researchers Study It
Dihexa occupies a unique position in neuropeptide research because of its extraordinary potency as a synaptogenic agent and its oral bioavailability with blood-brain barrier penetration. Its mechanism via the HGF/c-Met pathway is mechanistically distinct from all other cognitive peptides, offering potential insights into structural neuroplasticity and memory formation.
Proposed Mechanisms
- Binds hepatocyte growth factor (HGF) receptors, activating the c-Met signaling cascade
- Triggers PI3K/AKT pathway, promoting dendritic spine formation and synaptic connectivity
- Amplifies synaptogenesis at rates reported as 7× greater than BDNF alone
- Structural changes in dendritic spines persist weeks after administration ceases
- Crosses blood-brain barrier with high efficiency; orally bioavailable
Evidence Snapshot
| Study Type | Model | Outcome | Link |
|---|---|---|---|
| Animal (APP/PS1 mouse) | Alzheimer's disease model — cognitive impairment | Dihexa rescued cognitive impairment and recovered memory via PI3K/AKT signaling pathway activation | Source |
| Animal (rat) | Scopolamine-induced memory impairment | Dramatic improvements in memory acquisition and retention tasks; potency exceeding BDNF | Source |
| Animal (non-human primate, 2026) | Dendritic spine density measurement | Measurable increases in dendritic spine density within 14 days at 5 mg/kg; synaptogenesis rates 7× BDNF | Source |
Commonly Discussed Benefits
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Safety & Cautions
- All published efficacy data from animal models only — no human clinical trials completed
- HGF/c-Met pathway involvement raises theoretical oncogenic risk concerns
- Long-term safety profile completely unknown in humans
- Removed from FDA Category 2 in April 2026; PCAC review scheduled before February 2027 (second session, alongside LL-37, GHK-Cu injectable, PEG-MGF, and Melanotan II)
- Not FDA-approved for any condition
Comparisons
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Citations
- [1] Benoist CC. et al. — Dihexa, a cognitive enhancer via HGF/c-Met. J Pharmacol Exp Ther. 2014 PubMed
- [2] Wang J. et al. — Dihexa rescues cognitive impairment in APP/PS1 mice via PI3K/AKT. Int J Mol Sci. 2021 PubMed
- [3] Dihexa Clinical Trials 2026 — Research Status Update. Real Peptides. 2026 PubMed
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