Dihexa started life in a Washington State University lab as a chemically modified piece of angiotensin IV. The compound's formal name is N-hexanoic-Tyr-Ile-(6)-aminohexanoic amide, and it carries several other tags you'll see on supplier sites: PNB-0408, ATH-1001, and CAS number 1401708-83-5. It was invented by Joseph Harding and colleagues, who patented it as a small, blood-brain-barrier-penetrant angiotensin IV analog (Wikipedia).
The proposed mechanism is what drew attention. Rather than acting on angiotensin receptors, dihexa was reported to bind hepatocyte growth factor (HGF) and amplify signaling through HGF's receptor, c-Met. A 2014 paper in the Journal of Pharmacology and Experimental Therapeutics described saturable, high-affinity binding to HGF (a reported Kd around 65 pM) and argued that the peptide's memory effects in rats depended on the HGF/c-Met system: an HGF antagonist injected into the brain blocked the cognitive benefit of orally dosed dihexa in Morris water maze tests (JPET 2014, via PMC).
What the research actually showed, and a big caveat
The documented work is preclinical. In rodent models, dihexa was reported to improve spatial learning in aged animals and to reverse scopolamine-induced deficits, and it was described as far more potent than BDNF in promoting synapse formation. Those are animal findings. No completed human clinical trial of dihexa itself has been published.
The caveat is unavoidable. Several foundational papers from the originating lab drew expressions of concern over apparently manipulated western blot images, and the 2014 JPET paper cited above was retracted in 2025 (Retraction Watch). That doesn't erase the idea, but it means the early evidence for dihexa's mechanism and potency should be read with real skepticism.
The clinical program used a different molecule
Dihexa was licensed to M3 Biotechnology, which became Athira Pharma in 2019. Athira did not advance dihexa itself. It developed fosgonimeton (ATH-1017), described as a prodrug related to the dihexa chemistry, given by subcutaneous injection. That program failed: the Phase 2 ACT-AD trial missed its primary endpoint in 2022, and the larger Phase 2/3 LIFT-AD trial missed its primary and key secondary endpoints in 2024, after which Athira discontinued the Alzheimer's program (Alzforum). So even the closely related clinical candidate did not show benefit in people.
Regulatory and quality notes
Dihexa is not an approved drug anywhere. It is sold only as a research chemical, labeled research use only and not for human consumption. It is not a recognized dietary supplement, and nothing here is medical, dosing, or efficacy advice. WADA does not list dihexa by name, though growth-factor pathway modulators sit in territory athletes should treat cautiously; check current rules directly.
Because there is no pharmaceutical-grade source, anything on the market is unregulated. Identity and purity vary by vendor, so a recent third-party certificate of analysis (mass spec for identity, HPLC for purity) is the only objective check a buyer has. peptideone aggregates published COAs and independent vendor ratings rather than endorsing any seller.