Dihexa
$Experimental nootropic; Preclinical evidence with research-integrity cautions
Dihexa is a synthetic angiotensin-IV-derived compound marketed as a cognitive and neurorepair peptide. The key point is that it is neither an approved medicine nor a clinically validated nootropic. It is better understood as a research compound with interesting preclinical signals and unusually large uncertainty.
Its strongest claims came from preclinical work, not human trials. A central HGF/c-Met mechanism paper was later retracted, and an earlier foundational Dihexa paper received a formal notice of concern. That does not prove every idea about Dihexa is false, but it sharply lowers confidence in strong claims.
This entry warrants more skepticism than usual. Mechanism, dosing, half-life, human safety, and long-term risk are not established. Treat vendor claims of precise dosing, long duration, or guaranteed cognitive enhancement as unsupported unless they cite human PK and controlled human outcome data.
Classification details
- Dihexa, also called PNB-0408, is a synthetic angiotensin IV analog.
- Chemically, it is a small modified oligopeptide described as N-hexanoyl-Tyr-Ile-(6) aminohexanoic amide.
- It was designed to overcome the usual weaknesses of short peptides: rapid degradation, poor oral exposure, and limited blood-brain barrier penetration.
- In practical terms, it sits between peptide pharmacology and small-molecule nootropic research rather than behaving like a standard hormone peptide.
- The intended therapeutic concept was neurorepair: use a stable AngIV-derived scaffold to support synapse formation and memory processes.
- That concept remains investigational. Dihexa is not FDA-approved, has no labeled human indication, and does not belong with clinically used neuroactive drugs such as prescription stimulants, cholinesterase inhibitors, or approved dementia therapies.
- Dihexa is an angiotensin-IV-derived nootropic research compound often discussed for synaptogenesis. It is distinct from ordinary peptides because it is designed for CNS penetration and strong trophic signaling hypotheses.
- The proposed mechanism is positive modulation of the hepatocyte growth factor / MET receptor system, often written HGF/c-Met or HGF/MET.
- HGF and MET are involved in cell survival, migration, tissue remodeling, neurodevelopment, and synaptic plasticity.
- Dihexa was proposed to bind or stabilize HGF in a way that enhances MET activation when HGF is present.
- This mechanism must be framed cautiously.
- The paper most often cited for the HGF/c-Met mechanism was retracted in 2025, and an earlier Dihexa paper received a formal notice of concern.
- A safer phrasing is: Dihexa has been proposed to interact with HGF/MET signaling, and later animal studies have explored related neuroplasticity pathways, but the specific mechanism is not settled enough to treat as proven.
- The safety tension is obvious: the same pathway discussed for neuronal repair is also a major pathway in cancer biology.
- HGF/MET signaling participates in proliferation, migration, invasion, angiogenesis, and metastasis in many tumors.
- That does not mean Dihexa causes cancer, but it does mean arbitrary long-term HGF/MET potentiation without human toxicology is not a trivial risk.
- The main mechanism claim involves HGF/c-Met pathway modulation and synaptogenic signaling. Because c-Met biology is also relevant to cancer and tissue growth, mechanism language needs a benefit-risk boundary.