Dihexa: Rodent Memory Data and the Retraction Behind It
An oral angiotensin IV analog studied as a memory aid in rodents — the foundational animal paper now carries a formal notice of concern, and no human trial exists.
What is Dihexa?
Dihexa is a small-molecule angiotensin IV analog studied in rodents as a potential memory-enhancing compound, working through the HGF/c-Met growth-signaling pathway in the brain. The foundational 2013 animal study reported memory restoration in impaired rodents, but no human trial has ever been published, and in 2021 the journal attached a formal notice of concern to that paper. There's also an unresolved safety question: the HGF/c-Met pathway dihexa acts on is one that some cancers also use to grow, and whether that raises tumor risk in people has never been tested.
Quick facts
- Class
- Angiotensin IV analog (small molecule, not a peptide), HGF/c-Met pathway
- Solubility
- Oral capsule/liquid — no reconstitution required
- Brand Names
- No trademarked brand — sold as a research compound
- Legal Status
- Not FDA-approved for human use — research use only (RUO). No human trials published; foundational animal paper carries a 2021 notice of concern
- Category
- Cognitive Enhancement
- Storage
- Room temperature, sealed, away from light and moisture. No refrigeration or reconstitution required.
- Half-Life
- Not established in humans. Engineered to resist enzymatic breakdown, long-acting in animal studies.
Dosing at a glance
Doses shown are those reported in published research, not a recommendation.
What the evidence supports
| Claim | Grade | Basis |
|---|---|---|
| Cognitive Enhancement | Fgrade | McCoy 2013 (J Pharmacol Exp Ther): memory restoration in impaired rodents only. No human trial. The journal attached a notice of concern in 2021, and two related dihexa papers were retracted in April 2025 after a university investigation found falsified data. |
Dihexa Mechanism of Action
An Angiotensin IV Analog Targeting HGF/c-Met
Dihexa is a metabolically stabilized analog of angiotensin IV, engineered to survive oral administration and activate the HGF/c-Met (hepatocyte growth factor / c-Met receptor) signaling pathway in the brain — a pathway involved in synaptogenesis and neuronal growth, distinct from the BDNF/TrkB mechanism used by nootropic peptides like Semax.
Not a Peptide
Despite its origin as an angiotensin peptide fragment analog, dihexa itself is a small molecule, engineered specifically for oral bioavailability and blood-brain barrier penetration — structurally quite different from the injectable peptides in this catalog.
Dihexa Dosage and Protocols
Research Protocol Range
Research-vendor products are commonly dosed at 5-20mg orally once daily. Since the foundational evidence is animal-only and the key paper is flagged, this range reflects informal research-community convention rather than any validated human dose-finding data.
Dihexa Side Effects and Safety
No Human Safety Data
Because no human trial has been published, dihexa has no characterized human side-effect profile. Given the untested HGF/c-Met cancer-pathway question, active malignancy and personal/family cancer history are treated as meaningful contraindications here — more seriously than the general precautionary language used for most unapproved compounds in this catalog.
Dihexa Research Evidence
One Animal Paper, Now Flagged
The foundational study (McCoy et al., 2013, J Pharmacol Exp Ther) reported that dihexa restored memory in cognitively impaired rodents. This is the primary evidence behind dihexa's reputation as a research nootropic. In 2021, the journal attached a formal notice of concern to this paper — a real, documented red flag on the foundational evidence, not a hypothetical one.
An Untested Cancer-Pathway Question
The HGF/c-Met pathway dihexa activates is also a pathway some cancers exploit to grow and spread — whether chronic dihexa use raises tumor risk in people has never been studied. Combined with the complete absence of human trial data and the notice of concern on the key animal paper, dihexa carries meaningfully more uncertainty than most compounds in this catalog.
Regulatory and Legal Status
Dihexa has no FDA-approved indication and is not approved for human consumption. It is sold exclusively as a research-grade compound (RUO). Given the notice of concern on its foundational study and the untested cancer-pathway question, researchers and users should weigh dihexa's evidence base especially carefully and verify legal status in their jurisdiction before use.
Dihexa Stacking and Combinations
Sometimes Paired With Semax/Selank
Dihexa is sometimes combined with Semax or Selank in informal nootropic research stacks, on the logic of pairing HGF/c-Met signaling with BDNF/TrkB pathway activation. No formal combination trial data exists, and neither individual compound's combination safety has been studied.
Dihexa Pharmacokinetics
Not Established in Humans
No human pharmacokinetic study — absorption, half-life, clearance — has been published for dihexa. Available PK-adjacent data comes exclusively from the flagged rodent study.
Contraindications
- pregnancy
- active malignancy
- personal/family history of cancer
Frequently asked questions
What is a typical Dihexa dose?
Published research protocols report 5–20 mg, 1x daily. This is the range described in the literature, not a recommendation.
What is the half-life of Dihexa?
Not established in humans.
Is Dihexa backed by strong evidence?
Dihexa carries a REGEN research grade of F. REGEN Research Tier F — animal-only evidence, and the foundational paper carries a formal notice of concern.
How is Dihexa administered?
Routes reported in the literature: oral.
Who should avoid Dihexa?
Contraindications noted in the literature include pregnancy, active malignancy, personal/family history of cancer.
References
- Evaluation of Metabolically Stabilized Angiotensin IV Analogs as Procognitive/Antidementia Agents · McCoy AT, et al. · 2013