Dihexa

What Is Dihexa?

Dihexa is a small oligopeptide developed from angiotensin IV, a naturally occurring peptide involved in learning, memory, and blood flow regulation. It was designed to bind hepatocyte growth factor (HGF) and amplify activity at the c-Met receptor, a signaling pathway proposed to drive new synaptic connections between neurons.

The 2012 paper from the Harding lab that originally characterized dihexa-class molecules as HGF-dimerization mimetics was formally retracted in April 2025, following a 2021 notice of concern. That retraction affects the foundational mechanistic claim and is essential context for weighing other claims about the compound.

What Dihexa Is Being Researched For

• Synaptic Connectivity in Cell Culture

  Early in vitro research measured dihexa's effect on dendritic spine formation in cultured neurons, comparing it with BDNF at a narrow assay endpoint.^[1]

• Cognitive Function in Rodent Models

  Animal studies examined dihexa in rodent models of impairment resembling Alzheimer's disease, reporting changes attributed to enhanced synaptic connectivity.

• Oral Bioavailability and Brain Access

  Rodent research examined apparent oral bioavailability and blood-brain barrier penetration, properties that distinguished dihexa from many injectable research peptides.

How Dihexa Works

• Amplifying HGF Activity at the c-Met Receptor

  Research proposed that dihexa binds hepatocyte growth factor and potentiates its activity at the c-Met receptor, driving structural changes that support new synaptic connections.^[2] The original 2012 paper establishing this mechanism has since been retracted.

• A Different Pathway Than Common Nootropics

  The proposed mechanism operates through growth-factor and receptor signaling rather than the neurotransmitter systems targeted by stimulants or acetylcholinesterase inhibitors, if the underlying mechanism holds up to further scrutiny.

Reconstitution and Handling

Dihexa is typically supplied in capsule form for oral research use. Capsules should be stored in a cool, dry place away from direct light and handled according to the specific product's labeling since formulations can vary by supplier.

Key Takeaways

Dihexa's research history includes a significant complication: the foundational 2012 paper establishing its core HGF-amplification mechanism was formally retracted in 2025. All available evidence remains limited to rodent and cell culture studies, with no human trials conducted or registered. The retraction is central to evaluating the compound, not a minor footnote.

Frequently Asked Questions

Sources and Research

1. Benoist CC, et al. The procognitive and synaptogenic effects of angiotensin IV-derived peptides are dependent on activation of the hepatocyte growth factor/c-Met system. J Pharmacol Exp Ther. 2014;351(2):390-402.
2. Kawas LH, et al. [Retracted, April 2025] Contribution of the Hepatocyte Growth Factor/c-Met System to Memory and Neurodegeneration. J Pharmacol Exp Ther. Originally published 2012.