Evidence memo / Neuro & mental health

Dihexa

Also: PNB-0408 · angiotensin IV analog

Dihexa is a small molecule derived from angiotensin IV, studied in animals for effects on learning, memory, and the formation of nerve connections. Its evidence is almost entirely preclinical, with no published human trials. It is not an approved drug and is sold in the gray market as a nootropic. The Watchlist boundary is keeping it to its preclinical research context and not treating animal findings as proof of human cognitive benefit.

No human data yetPreclinicalSafety / regulatory watch

The verdict

Our read at a glance.

Whether dihexa's preclinical effects on learning and nerve connections in animals support the cognitive-enhancement claims made for it in humans.

The signal
Most dihexa research is laboratory and animal work, suggesting effects on memory and the growth of nerve connections. There are no published human trials, so its safety and benefit in people are unknown. It is not approved for any use.
The unknown
Whether any of the animal cognitive effects occur in humans at all, and what the safety of promoting nerve-connection growth would be, neither of which has been tested.
Our read
Striking animal data, zero human evidence. Its preclinical effects are striking, but with no human trials and an uncertain safety picture, the cognitive claims made for it are unproven, and it should be read as a research compound.

The mechanism

How it works.

Dihexa is a small synthetic molecule derived from angiotensin IV, built to cross into the brain and stay active. The proposed mechanism is that it binds hepatocyte growth factor (HGF) and amplifies its signaling through the c-Met receptor, which in animal and cell studies promotes the formation of new connections (synapses) between nerve cells. That synapse-building action is the basis for the memory effects seen in rodents, but it rests entirely on animal and laboratory data, there are no published human trials, and whether it works this way or is safe in people is unknown.

Safety & regulatory boundary

The consequential part.

Dihexa is not an approved drug and has not been tested in published human trials. It is sold as a research chemical, where product identity and quality are uncertain. Promoting the growth of nerve connections is not obviously safe, and animal findings do not establish human cognitive benefit. Gray-market products are not a studied or approved preparation.

What's next

What we're watching.

Whether it ever enters controlled human trials, and any safety data if it does.

Context

Why this is discussed.

Dihexa is promoted as a powerful nootropic based on striking animal data about nerve-connection growth, which makes it popular even though it has not been tested in people.

The evidence base

12 cited references.

Indexed literature (PubMed)12

Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions

Rahman OF et al. · J Am Acad Orthop Surg Glob Res Rev · 2026

Physiopathology of the Brain Renin-Angiotensin System

Cueto-Ureña C et al. · Life (Basel) · 2025

[The renin-angiotensin system and the brain]

Molina-Van den Bosch M et al. · Hipertens Riesgo Vasc · 2021

Within the Brain: The Renin Angiotensin System

Jackson L et al. · Int J Mol Sci · 2018

Cognitive-enhancing effects of angiotensin IV

Gard PR · BMC Neurosci · 2008

Keep reading

Related published memos.