Dihexa is an experimental peptidomimetic studied for effects on cells and memory in animals. It has not been shown to improve memory or reverse dementia in people.
The central early paper connecting Dihexa to HGF/MET signaling was retracted in 2025. Later animal findings include both positive and negative results. Human studies of the related investigational prodrug fosgonimeton answer a different question—and its larger Alzheimer’s trial did not meet its clinical endpoints.
People searching for Dihexa usually want to know whether it helps cognition, how it works, and whether the safety claims are credible. The useful answer requires separating the molecule, the proposed mechanism, individual experiments, and actual human outcomes. This guide follows those distinctions without turning a research finding into a treatment recommendation.
What is Dihexa?
Dihexa, also called PNB-0408 in the research literature, is a synthetic peptidomimetic: a molecule designed from peptide chemistry with structural modifications. It emerged from research on analogs of angiotensin IV, a naturally occurring peptide. Calling it a “Dihexa peptide” describes that research lineage, but it is not intact angiotensin IV, a six-amino-acid sequence to read from its name, or the growth-factor protein HGF.
C27H44N4O5
504.7 g/mol
Molecular identity specifies the reference chemical.
Salt and formulation describe the supplied material.
Capsule count and content describe a product configuration and analytical result.
Why was it studied for cognition?
Researchers explored whether modified angiotensin IV compounds could influence memory-related signaling and synaptic function. A 2015 development review describes the program’s rationale. A 2018 systematic review examined nonhuman experiments across angiotensin IV, its analogs and another angiotensin peptide. Its positive synthesis is not a set of human Dihexa trials, and it predates the later retractions.
Even within this chemical family, biological direction can differ. The older norleual study, which has a published correction, concerned an HGF/MET inhibitor. Norleual is a different compound. Its inhibitory findings cannot be assigned to Dihexa or used as proof that Dihexa prevents cancer.
How does HGF/MET relate to Dihexa?
Hepatocyte growth factor, or HGF, is a signaling protein. MET is its cell-surface receptor. The foundational experiments identifying that receptor and mapping its ligand-binding regions are separate from the later Dihexa literature. Bottaro and colleagues directly identified MET as the HGF receptor; Gherardi and colleagues mapped functional parts of its extracellular domain.
Pathway activation also does not mean that every downstream effect occurs together. A 1992 HGF-domain experiment found receptor binding and epithelial-cell scattering without the same mitogenic response. Binding, cell movement, proliferation, synaptic changes and memory are different measurements.
What can we say about the mechanism now?
Dihexa has been described as an HGF/MET positive modulator. However, the influential 2014 paper supporting that chain of explanation was retracted. Later experiments can provide new evidence, but should be evaluated for what they actually measured: a behavioral result, an inhibitor experiment or a cell-response assay is not automatically a direct molecular binding measurement.
The 2025 traumatic-brain-injury paper discussed below provides newer behavioral and cell-assay findings. It does not by itself settle the proposed HGF binding interaction, establish a human brain exposure profile, or validate an online claim that Dihexa is a particular number of times “stronger than BDNF.” A meaningful potency comparison would require matched materials, assays and endpoints.
Which early papers changed status?
Development and characterization
The paper evaluating metabolically stabilized angiotensin IV analogs has an expression of concern. The current record checked for this guide identifies that status; it should not be silently relabeled a retraction or used as an unquestioned source of human pharmacokinetics.
The central procognitive and synaptogenic mechanism paper
The retraction notice applies to the paper linking angiotensin IV-derived peptides to HGF/c-Met activation. It is cited here to document the correction to the record, not to support an efficacy claim.
2012
The surrounding HGF/MET analog literature
Separate notices cover HGF dimerization-domain mimics and angiotensin IV analogs as HGF/Met modifiers. These are distinct publications; they should not be counted as three independent confirmations of one Dihexa mechanism.
What this changes: an affected paper cannot carry the same evidentiary weight as an unaffected result. It does not follow that every later Dihexa experiment is invalid. New studies need their own assessment of material identity, controls, measurements and reproducibility.
What do later animal studies actually show?
These experiments test different disease models and endpoints. Their results cannot be pooled into a single “memory improvement” percentage.
A genetically modified Alzheimer’s model
Sun and colleagues reported better water-maze performance, changes in neuronal and synaptic markers, and reduced inflammatory signals after a three-month experiment. Swimming speed did not differ between groups, helping separate the maze result from that particular motor measure.
The full paper describes administration as both intragastric and intraperitoneal. That unresolved methods inconsistency prevents treating it as clean proof of oral performance. Its PI3K-inhibitor experiment also lacked an inhibitor-only comparison, a limitation the authors acknowledge. Mice carrying an Alzheimer’s model are not patients with dementia.
A five-week 3-nitropropionic-acid experiment
The PNB-0408 study used 40 male Wistar rats divided among vehicle, toxin, and toxin-plus-compound groups. The toxin produced lower weight gain and cognitive and motor deficits. Adding PNB-0408 did not prevent the reported impairments.
This negative finding belongs alongside positive studies. It limits general claims of neuroprotection; it does not prove the compound has no effect in every other experimental system.
A newer working-memory experiment
Martino and colleagues studied rats after repeated mild traumatic brain injury. Dihexa was delivered into a brain ventricle before testing. The higher tested exposure produced 81.5% correct T-maze responses, compared with 67.1% in the injured vehicle group. A peptide antagonist blocked the improvement.
This was a short behavioral assessment, not evidence of durable recovery in people. The reported maze-session duration comparison was not statistically significant. A separate canine kidney-cell assay measured E-cadherin redistribution; it was not a direct Dihexa–HGF binding assay. Direct brain delivery also provides no demonstration that a swallowed capsule reaches the same target exposure.
What about hair cells, liver cells and peripheral nerves?
Other work is useful but answers different questions. A 2015 larval-zebrafish study reported protection of hair cells from aminoglycoside injury; this is not demonstrated hearing restoration in people. A 2021 rat nerve-injury study included stem cells, GCSF and Dihexa across multiple groups. Benefits in combination conditions do not identify the contribution of Dihexa alone.
Human pluripotent cells have also been differentiated toward liver-cell lineages using chemical mixtures that include Dihexa. The 2015 study, 2016 protocol and 2022 vitamin C–Dihexa–forskolin work concern cell-generation systems. “Human cells” in a laboratory is not the same as “human participants treated with Dihexa.”
Has Dihexa been studied in people?
The studies reviewed here do not establish that taking a Dihexa product improves memory, treats dementia or repairs a brain injury. The related clinical-development program must be named precisely: fosgonimeton, formerly ATH-1017, is a prodrug; its active metabolite is called fosgo-AM, formerly ATH-1001. The 2023 development paper describes this compound program and its preclinical findings. Those trial formulations and exposures are not interchangeable with an unapproved Dihexa capsule.
In a 2022 phase I report, 88 participants included healthy younger adults, healthy older adults and 11 people with Alzheimer’s disease. An electrophysiological signal in the small Alzheimer’s subgroup was exploratory evidence after short exposure, not a demonstrated improvement in everyday memory. Later clinical outcomes are more informative for an efficacy claim.
Small numerical differences did not establish clinical benefit.
The combined cognition/function endpoint had p = 0.70; the cognition scale had p = 0.35, and the daily-function scale p = 0.61. Nominal exploratory biomarker findings did not turn these into successful clinical endpoints.
Published LIFT-AD report. The full study randomized 554 participants; 549 received study medication. Those totals differ from the 287-person primary-analysis population. This panel summarizes the specified primary analysis, not a retail Dihexa trial.
Adverse-event discontinuation was more frequent with fosgonimeton than placebo, largely due to administration-site reactions. That safety profile concerns the studied prodrug and formulation; it does not establish the safety of another product.
Registry searches checked on September 9, 2026 returned no records for the exact Dihexa and PNB-0408 queries. An ATH-1001 search did return a completed eight-participant radiolabeled-fosgonimeton study measuring absorption, metabolism and excretion. This is why a keyword match must be checked against the actual intervention. Search absence is limited to these queries and date, not proof about every possible registry or unpublished experiment.
What about benefits, side effects and an oral timeline?
Does it reverse cognitive decline?
No credible conclusion of human reversal follows from the studies above. Better animal-task performance, cell markers and exploratory electrical signals are different from improved cognition and daily function in patients.
How quickly does it work?
A study’s observation period is not a personal onset time. Rat tests soon after direct brain administration, a three-month mouse experiment with inconsistent route reporting, and a 26-week prodrug trial cannot supply an oral Dihexa timeline.
Does it cause cancer?
MET is a growth-related proto-oncogene receptor, so effects on its signaling deserve careful safety study. That biological concern is not a measured human Dihexa cancer rate. The evidence reviewed here establishes neither a cancer-causing conclusion nor reassurance that long-term exposure is safe.
Is a high-purity capsule safe?
Chemical analysis can describe the tested sample. It does not supply human tolerability, interaction, reproductive-safety or long-term outcome data. A measured content value cannot make those missing studies unnecessary.
Current U.S. regulatory context: the FDA’s compounding safety page specifically names Dihexa acetate. The agency reports insufficient safety information and no identified human-exposure data for drug products containing that substance. This is a substance-specific assessment, not an approval or a finding that a commercially listed product is safe.
Its nomination appears among withdrawn nominations. FDA has announced an intended advisory-committee discussion before the end of February 2027. An announced review is not a completed vote, inclusion decision or drug approval. Status checked September 9, 2026.
How do you read a Dihexa product record?
The current Apex Dihexa listing uses a 10 mg, 60-piece configuration. Its published report expresses content per capsule. Read those as separate quantities, rather than interpreting “60pcs” as 60 mg or treating the product as a liquid formulation.
On a narrow screen, scroll the table horizontally. Keyboard users can focus the table region and use the arrow keys.
| Quantity | Published example | What it does—and does not—tell you |
|---|---|---|
| Label / pack | 10 mg · 60 pieces | Configuration wording. Pack count is not the mass of one capsule. |
| Measured active content | 10.0085 mg/capsule | The reported per-capsule analytical result; not a recommended human amount. |
| Document identity | APX-2026-0404-D Issued April 4, 2026 |
A dated lot-specific record. It does not promise that a future shipment is the same lot. |
Source: the published Dihexa configuration report and its attached PDF. Match the actual product, lot, method and units. A chromatographic result and an active-content result answer different analytical questions; neither establishes clinical efficacy. Our guide to reading a peptide COA explains those distinctions.
Frequently Asked Questions about Dihexa
What is Dihexa used for in research?
Dihexa is studied in cell systems and animal models involving memory, neuronal responses, hair-cell injury and chemical cell differentiation. Those experimental uses do not establish an approved treatment or human cognitive benefit.
Does Dihexa improve memory in humans?
The evidence reviewed here does not establish that a Dihexa product improves human memory. Positive animal-task findings are model-specific. The larger published trial of related fosgonimeton did not meet its primary or secondary endpoints.
Is Dihexa the same as HGF or angiotensin IV?
No. HGF is a signaling protein, angiotensin IV is a naturally occurring peptide, and Dihexa is a synthetic peptidomimetic developed from an angiotensin IV analog program. A shared research pathway does not make these materials interchangeable.
Was the Dihexa research retracted?
The central 2014 HGF/c-Met mechanism paper and two related analog papers were retracted in 2025. A separate 2013 development paper has an expression of concern. Later studies need their own evaluation; it is inaccurate to describe the entire Dihexa literature as either unaffected or retracted.
Is Dihexa stronger than BDNF?
A numerical stronger-than-BDNF claim is not supported by a matched clinical comparison in the evidence reviewed here. Different assays, molecules and biological endpoints cannot be combined into a meaningful human potency ratio.
Do oral Dihexa studies establish a capsule timeline?
No reliable human capsule timeline follows from these studies. The 2021 mouse paper conflicts on administration route, and the 2025 rat-injury experiment delivered Dihexa directly into a brain ventricle. Neither establishes human oral absorption or onset.
Is fosgonimeton a human trial of an online Dihexa product?
No. Fosgonimeton is an investigational prodrug with its own formulation, metabolism and trial exposures. Its active metabolite is called fosgo-AM or ATH-1001. The clinical findings cannot be assumed to apply to a separately supplied Dihexa research product.
What is known about Dihexa side effects and cancer risk?
Human tolerability and long-term risks are not established by the evidence reviewed here. MET pathway biology provides a reason for careful safety study, not a measured human cancer rate. A lack of adequate safety data is not evidence that use is safe.
Is Dihexa FDA approved?
The FDA material reviewed here does not establish approval for Dihexa. Its safety page specifically identifies Dihexa acetate and important missing safety information. A withdrawn compounding nomination or announced committee discussion is not drug approval.
What does the Dihexa 10 mg, 60-piece report mean?
The label and pack count describe a configuration. The dated APX-2026-0404-D report separately states 10.0085 mg of active content per capsule. That measured result applies to the documented sample and is not a human-use recommendation or a promise about every future lot.
Sources and scope
This guide distinguishes original experiments, reviews, an expression of concern and retraction notices. PubMed records and current registry entries were checked in September 2026. The 2021 mouse, 2025 rat-injury and published LIFT-AD reports were read beyond their abstracts; limitations visible in those reports are kept in the interpretation. Studies using related compounds or mixtures are identified explicitly.
- Hartmann G et al. A functional domain in the heavy chain of scatter factor/hepatocyte growth factor binds the c-Met receptor and induces cell dissociation but not mitogenesis.. Proceedings of the National Academy of Sciences of the United States of America. 1992. PMID 1280830.
- Gherardi E et al. Functional map and domain structure of MET, the product of the c-met protooncogene and receptor for hepatocyte growth factor/scatter factor.. Proceedings of the National Academy of Sciences of the United States of America. 2003. PMID 14528000.
- Bottaro DP et al. Identification of the hepatocyte growth factor receptor as the c-met proto-oncogene product.. Science (New York, N.Y.). 1991. PMID 1846706.
- Yamamoto BJ et al. The angiotensin IV analog Nle-Tyr-Leu-psi-(CH2-NH2)3-4-His-Pro-Phe (norleual) can act as a hepatocyte growth factor/c-Met inhibitor.. The Journal of pharmacology and experimental therapeutics. 2010. PMID 20086056.
- Wright JW et al. The development of small molecule angiotensin IV analogs to treat Alzheimer's and Parkinson's diseases.. Progress in neurobiology. 2015. PMID 25455861.
- Uribe PM et al. Hepatocyte growth factor mimetic protects lateral line hair cells from aminoglycoside exposure.. Frontiers in cellular neuroscience. 2015. PMID 25674052.
- Siller R et al. Small-molecule-driven hepatocyte differentiation of human pluripotent stem cells.. Stem cell reports. 2015. PMID 25937370.
- Mathapati S et al. Small-Molecule-Directed Hepatocyte-Like Cell Differentiation of Human Pluripotent Stem Cells.. Current protocols in stem cell biology. 2016. PMID 27532814.
- Ho JK et al. Cognitive benefits of angiotensin IV and angiotensin-(1-7): A systematic review of experimental studies.. Neuroscience and biobehavioral reviews. 2018. PMID 29733881.
- Weiss JB et al. Stem cell, Granulocyte-Colony Stimulating Factor and/or Dihexa to promote limb function recovery in a rat sciatic nerve damage-repair model: Experimental animal studies.. Annals of medicine and surgery (2012). 2021. PMID 34703584.
- Sun X et al. AngIV-Analog Dihexa Rescues Cognitive Impairment and Recovers Memory in the APP/PS1 Mouse via the PI3K/AKT Signaling Pathway.. Brain sciences. 2021. PMID 34827486.
- Hua X et al. Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of the Positive Modulator of HGF/MET, Fosgonimeton, in Healthy Volunteers and Subjects with Alzheimer's Disease: Randomized, Placebo-Controlled, Double-Blind, Phase I Clinical Trial.. Journal of Alzheimer's disease : JAD. 2022. PMID 35180125.
- Pan T et al. Efficiently generate functional hepatic cells from human pluripotent stem cells by complete small-molecule strategy.. Stem cell research & therapy. 2022. PMID 35410439.
- Johnston JL et al. Fosgonimeton, a Novel Positive Modulator of the HGF/MET System, Promotes Neurotrophic and Procognitive Effects in Models of Dementia.. Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics. 2023. PMID 36538176.
- Wells RG et al. Effects of an Angiotensin IV Analog on 3-Nitropropionic Acid-Induced Huntington's Disease-Like Symptoms in Rats.. Journal of Huntington's disease. 2024. PMID 38489193.
- Kawas LH et al. Retraction notice to "Development of Angiotensin IV Analogs as Hepatocyte Growth Factor/Met Modifiers" [J Pharmacol Exp Ther 340 (2012) 539-548].. The Journal of pharmacology and experimental therapeutics. 2025. PMID 40312092.
- Benoist CC et al. Retraction notice to "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 351 (2014) 390-402].. The Journal of pharmacology and experimental therapeutics. 2025. PMID 40312093.
- Kawas LH et al. Retraction notice to "Mimics of the Dimerization Domain of Hepatocyte Growth Factor Exhibit Anti-Met and Anticancer Activity" [J Pharmacol Exp Ther 339 (2011) 509-518].. The Journal of pharmacology and experimental therapeutics. 2025. PMID 40312094.
- Porsteinsson AP et al. Fosgonimeton in mild-to-moderate Alzheimer's disease.. Journal of Alzheimer's disease reports. 2025. PMID 41393340.
- Martino KA, Nakhre A, Demarest RM, Devilbiss DM. Hepatocyte Growth Factor/MET Activator Rescues Working Memory Deficits after Repeated Mild Traumatic Brain Injury. Neurotrauma Reports. 2025. DOI: 10.1177/2689288X251392851.
- Editorial notice. Notice of Concern concerning the 2013 evaluation of metabolically stabilized angiotensin IV analogs. Journal of Pharmacology and Experimental Therapeutics. 2021. The notice does not list an individual author.
Continue your research
Use the CNS research overview to compare the distinct evidence questions surrounding other compounds. For Dihexa’s available configuration and current price, use the product listing; for analytical documentation, open its linked report. This guide evaluates research and does not select a personal regimen.
Research-use boundary
For in-vitro research use only. Not for human consumption. Apex Laboratory supplies research materials. This educational discussion of published animal and human studies is not a recommendation to administer those materials, treat a condition or replace medical care.
