Dihexa Protocol

Dosing & Research

Last Updated: September 4, 2026

Also known as: PNB-0408, N-hexanoic-Tyr-Ile-(6)-aminohexanoic amide

Chemical Identity

Amino Acid Sequence: N-hexanoic-Tyr-Ile-(6)-aminohexanoic amide
Molecular Formula: C27H44N4O5
Molecular Weight: 504.67 g/mol
CAS Number: 1401708-83-5

Synaptogenesis and dendritic-spine formation research, HGF/c-Met pathway modulation studies, Animal cognitive/memory models, Oral angiotensin IV analog pharmacology

Evidence Level

Preclinical Only -- Foundational Papers Retracted

Species Studied

Rodent • In vitro

Half-Life

Not Well Characterized In Humans

Administration

Oral

Frequency

Per study protocol; no established human schedule

How It Works

Orally active angiotensin IV analog originally proposed to positively modulate the HGF/c-Met signaling pathway, promoting dendritic spine formation and synaptogenesis in animal neuron models. Caution: the foundational mechanism papers from the originating laboratory (Kawas, Wright, Harding et al.) were formally retracted in April 2025 following a Washington State University research-misconduct investigation that found falsified/fabricated image data, so the HGF/c-Met mechanism should be treated as unconfirmed pending independent replication.
Synaptogenesis and dendritic-spine formation research
HGF/c-Met pathway modulation studies
Animal cognitive/memory models
Oral angiotensin IV analog pharmacology

Dosing Structure

Dose

Preclinical research only

Frequency

Per study protocol; no established human schedule

Notes

Entirely preclinical (rodent cognitive and cell-culture spine-density studies); zero completed human clinical trials and no independent replication of the retracted foundational mechanism papers. Animal oral research ranges of roughly 1-3 mg/kg have been reported; separate, non-validated community references cite 5-20 mg oral daily in short cycles. Not injectable. Research and laboratory reference only -- not medical advice.

Example Protocols

Dose: Preclinical research only

Frequency: Per study protocol; no established human schedule

Duration: Not Established In Humans

Off Period: Not listed

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Protocol Notes

•

Entirely preclinical (rodent cognitive and cell-culture spine-density studies); zero completed human clinical trials and no independent replication of the retracted foundational mechanism papers.

•

Animal oral research ranges of roughly 1-3 mg/kg have been reported; separate, non-validated community references cite 5-20 mg oral daily in short cycles.

•

Not injectable.

•

Research and laboratory reference only -- not medical advice.

What Is Dihexa?

Dihexa (PNB-0408) is an orally active, synthetic angiotensin IV analog studied in rodent models for its proposed ability to promote synaptogenesis and dendritic spine formation. It is not derived from an approved drug and has zero completed human clinical trials. Critically, the foundational laboratory papers describing its HGF/c-Met mechanism were formally retracted in April 2025 after a university investigation found falsified image data, so the evidence base behind Dihexa should be treated with significant caution pending independent replication.

Research Observations - Not Medical Claims

▸Origin: Dihexa emerged from an angiotensin IV analog research program at Washington State University aimed at developing orally bioavailable cognition-enhancing compounds.
▸Proposed mechanism: The compound was reported to positively modulate the hepatocyte growth factor (HGF)/c-Met signaling pathway, promoting dendritic spine formation and synaptogenesis in cultured neurons and rodent cognitive models.
▸Retraction (April 2025): Following a Washington State University research-misconduct investigation, the foundational 2012 mechanism paper (Kawas, McCoy, Yamamoto, Wright, Harding -- J Pharmacol Exp Ther) and a related paper describing Dihexa's procognitive/synaptogenic effects were formally retracted after the investigation found altered/fabricated image data in the first author's dissertation and co-authored papers.
▸No human data: There are no completed, registered human clinical trials evaluating Dihexa's safety, pharmacokinetics, or cognitive effects.

Evidence Summary

Preclinical Only -- Foundational Papers RetractedSynthetic research chemical; not FDA-approved for any indication. Not a peptide in the classical sense (small-molecule angiotensin IV analog). For research and laboratory reference only -- no medical or cognitive-enhancement claims.

Evidence StrengthLimited