VialOwlLibrary / Cognitive
Dihexa
Also known as PNB-0408, N-hexanoic-Tyr-Ile-(6) aminohexanoic amide
Animal studies only
Small peptide derived from angiotensin IV, proposed to act on the hepatocyte growth factor and c-Met system. Studied only in cells and animals for memory effects, and the main 2014 paper on how it works was retracted in April 2025.
Not an approved medicine. Dihexa is not an approved medicine for this use in Australia or the United States. This page summarises published research for information only. It is not a recommendation to use Dihexa, and VialOwl does not sell or supply it.
Background
A small modified peptide derived from angiotensin IV, developed at Washington State University in the early 2010s as an oral, brain penetrating candidate for dementia. A key 2014 paper describing its mechanism was retracted in 2025.
How it is thought to work
It was reported to bind hepatocyte growth factor (HGF) and boost signalling through its receptor c-Met, promoting new connections between brain cells in animals. The retraction of the main mechanism paper means this is uncertain.
What is claimed, and the evidence
| Claim | Evidence | Notes |
|---|---|---|
| Memory and learning improvement, dementia treatment | Animal studies only | Improved maze performance in rodent models including an Alzheimer mouse model. No human trials. |
| Nootropic brain enhancement in healthy people | No published evidence | Marketed online; the FDA says it has not identified any human exposure data. |
Side effects
| Effect | How often | Notes |
|---|---|---|
| Human side effects Serious | Frequency unknown | No human data exist. Because c-Met signalling drives growth in some cancers, boosting it raises a theoretical cancer concern that has not been studied. |
Warnings
- The FDA has not identified any human exposure data for any route of administration.
- The 2014 paper describing its mechanism was retracted in 2025 after an earlier expression of concern.
- HGF and c-Met signalling is involved in some cancers; long term effects of boosting it are unknown.
- Unapproved products bought online are not checked by any regulator for purity, sterility or strength; they may be contaminated, underdosed, overdosed or contain a different substance to the label.
Regulatory status
- Australia
- Not included on the ARTG (unapproved). Not specifically listed in the Poisons Standard (June 2026).
- United States
- Not FDA approved. Nomination withdrawn and removed from 503A Category 2 in April 2026; FDA stated it has not identified any human exposure data.
Sources
- Benoist et al. 2014 (retracted 2025), Procognitive and synaptogenic effects of angiotensin IV derived peptides (PubMed)
- Sun et al. 2021, Dihexa rescues cognitive impairment in APP/PS1 mice (PubMed)
- FDA: Certain bulk drug substances for use in compounding that may present significant safety risks
- PubMed: Retraction notice (2025) for the 2014 dihexa mechanism paper
Also in Cognitive
From the VialOwl library, reviewed 26 September 2026. For education and general information. It is not medical advice and not a recommendation to use Dihexa.