Dihexa is a peptidomimetic small molecule — C₂₇H₄₄N₄O₅, 504.67 g/mol, CAS 1401708-83-5 — built by capping a tyrosine–isoleucine core with a hexanoyl group at one end and a 6-aminohexanamide at the other. It was developed at Washington State University from angiotensin IV, and the caps were the whole point: they remove the bonds proteases cleave and raise lipophilicity far enough that the compound no longer dissolves in water. Helix Bio supplies it in solid form, which leaves the choice of solvent with the researcher. Research and laboratory use only; not for human or veterinary use, ingestion, injection, or administration by any route.
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Dihexa is formally N-hexanoic-Tyr-Ile-(6) aminohexanoic amide, and by IUPAC name (2S,3S)-N-(6-amino-6-oxohexyl)-2-[[(2S)-2-(hexanoylamino)-3-(4-hydroxyphenyl)propanoyl]amino]-3-methylpentanamide. It carries the developmental code PNB-0408, CAS registry number 1401708-83-5 and UNII 9WYX65A5C2.
It is widely catalogued as a peptide, and that description does not survive contact with the structure. Only two residues in the molecule are proteinogenic. Both ends of the chain are synthetic modifications rather than further residues, and every nitrogen in the molecule is an amide nitrogen. At 504.67 g/mol, engineered specifically to resist proteolysis and cross lipid membranes, it behaves as a small molecule in every way that matters to a laboratory. Peptidomimetic small molecule is the accurate description.
That distinction is not academic. It changes how the material is verified, because there is no sequence to confirm. It changes what a purity figure means, because area-percent from a peptide-style assay is not a small-molecule purity determination. And it changes how the compound dissolves, which is the practical difference between a working stock and a cloudy vial.
The compound descends from angiotensin IV, a hexapeptide fragment of the renin-angiotensin system studied for procognitive activity in rodents. Researchers at Washington State University truncated and modified that parent structure across a programme aimed at metabolically stable, brain-penetrant analogues, and Dihexa is where that programme ended. The relationship is one of provenance rather than equivalence: two residues carry over, everything around them is new, and angiotensin IV's own pharmacology should not be attributed to Dihexa without direct evidence.
Researchers should also treat circulating molecular data for this compound with caution. At least one widely syndicated monograph describes Dihexa as a three-amino-acid polypeptide with a different mass, and database identifiers are cited inconsistently across reference pages. CAS 1401708-83-5, UNII 9WYX65A5C2 and InChIKey XEUVNVNAVKZSPT-JTJYXVOQSA-N are the identifiers that resolve reliably.
The property that makes this compound interesting is also the one that makes its format a real decision rather than a packaging detail.
Supplier characterisation describes Dihexa as insoluble in water, with DMSO as the practical solvent, and published in vivo work has used mixed vehicle systems rather than aqueous ones. A solid presentation does not solve that. What it does is leave the solvent decision with the researcher, who can select a vehicle appropriate to the assay rather than inheriting one chosen at the point of manufacture.
Solid form also keeps a set of characterisation methods open. Melting point, appearance, elemental composition and NMR are all measurable on a solid and are foreclosed, or made considerably harder, once a compound is dispersed in an undisclosed co-solvent system. For a compound whose published molecular data disagrees between sources, retaining those methods has practical value.
Two things follow for anyone reconstituting from a vial. DMSO freezes at around 18.5 °C and takes up water readily, so a stock cycled repeatedly between bench and freezer will gain water, lose effective concentration, and can drop a lipophilic solute out of solution — aliquoting at preparation matters more here than for an aqueous peptide stock. And a solid must be weighed, which is an exposure route a sealed solution does not have; standard particulate-handling practice applies.
Researchers should keep the published Dihexa literature separate from the specifications of any commercial preparation. Published findings describe defined experimental systems, overwhelmingly in rodents, and do not validate any particular lot, purity, mass basis or vehicle.
Dihexa has been examined in the following areas:
The existence of published research does not establish that Dihexa is safe or effective for use in humans, and part of that published record has been formally corrected. Two papers from the originating laboratory were retracted in 2025 following a research-integrity investigation, and a further paper carries an expression of concern. Dihexa is not an FDA-approved drug in the United States and has never entered human clinical trials.
Two questions matter more for Dihexa than for a typical catalogue compound, and neither is answered by a product name.
The first is what the material actually is. Because Dihexa is routinely mislabelled as a peptide, and because commercial molecular data for it disagrees between sources, identity confirmation here is a small-molecule exercise. That means chromatographic purity with the method stated, a mass result consistent with C₂₇H₄₄N₄O₅ near 504.7, structural confirmation where the manufacturer provides it, and attention to the reference standard used for comparison. A purity percentage generated by peptide logic does not answer the question on its own, because there is no sequence to verify.
The second is what the stated mass represents. A solid is sold by weight, and the fraction of that weight that is Dihexa depends on the form supplied. Residual counterion content and degree of hydration both shift it, and at least one supplier monograph notes that batch molecular weights vary with hydration, which changes the solvent volume needed for a target concentration. The mass basis belongs on the certificate of analysis, not in the product name.
Helix Bio states that its research catalog uses independent HPLC testing for purity assessment and mass spectrometry for molecular identity confirmation, and that batch-specific Certificates of Analysis are available. A sitewide statement describes the catalog's testing approach; it is not a lot-level analytical result. For Dihexa specifically, researchers should verify the applicable product documentation and current lot information before use.
Dihexa is intended for qualified users working in legitimate laboratory or scientific research environments, including:
The product is not intended for personal experimentation, self-administration, human consumption, veterinary use or medical treatment.
| Specification | Details |
|---|---|
| Product Name | Dihexa |
| Research Category | Cognitive & Nootropic Research Compounds |
| Compound | Dihexa |
| Developmental Code | PNB-0408 |
| Scientific Name | N-hexanoic-Tyr-Ile-(6) aminohexanoic amide |
| IUPAC Name | (2S,3S)-N-(6-amino-6-oxohexyl)-2-[[(2S)-2-(hexanoylamino)-3-(4-hydroxyphenyl)propanoyl]amino]-3-methylpentanamide |
| Synonyms | PNB-0408, Hexanoyl-Tyr-Ile-Ahx-NH₂ |
| Compound Class | Peptidomimetic small molecule |
| Structural Description | Tyr-Ile core with N-terminal hexanoyl cap and C-terminal 6-aminohexanamide |
| Parent Compound | Angiotensin IV (provenance, not equivalence) |
| Molecular Formula | C₂₇H₄₄N₄O₅ |
| Molecular Weight | 504.67 g/mol |
| Exact Mass | 504.3312 |
| CAS Number | 1401708-83-5 |
| UNII | 9WYX65A5C2 |
| InChIKey | XEUVNVNAVKZSPT-JTJYXVOQSA-N |
| Defined Stereocentres | 3 |
| Proposed Target | Hepatocyte growth factor / c-Met pathway (see research section for evidence status) |
| Aqueous Solubility | Insoluble; refer to current product documentation for handling |
| Format | Solid |
| Molecular Form / Mass Basis | Refer to current lot-specific product documentation |
| Fill Mass | Refer to current product listing |
| Physical Appearance | Refer to current product documentation |
| Purity | Refer to current lot-specific product documentation |
| Identity Testing | Refer to applicable Certificate of Analysis |
| Packaging | Refer to current product listing |
| Storage | Follow current product-specific documentation |
| Intended Use | Research and laboratory investigation only |
| Human Use | Not intended for human consumption |
| Veterinary Use | Not intended for veterinary use |
| Manufacturer | Helix Bio |
| Country of Origin | Refer to current product documentation |
Dihexa's research record is preclinical, concentrated in rodent cognition and growth-factor pathway work, and it comes with a documented correction to part of its own literature.
Angiotensin IV Analogue Chemistry. The compound is the endpoint of a structure–activity programme that truncated and modified angiotensin IV to produce metabolically stable, brain-penetrant analogues. The N-terminal hexanoyl cap and C-terminal aminohexanamide raise lipophilicity and remove proteolytically labile bonds. That makes Dihexa a subject in its own right for work on how peptide-derived compounds can be converted into orally absorbed small molecules — and a useful case study in what that conversion costs, since the same modifications are why the compound will not dissolve in water.
Hepatocyte Growth Factor and c-Met Pathway Research. The proposed mechanism is that Dihexa binds hepatocyte growth factor and potentiates its activity at the c-Met receptor, with downstream effects through PI3K/AKT on dendritic spine formation. Two precisions matter. The proposal concerns binding to HGF rather than direct agonism at c-Met, so descriptions saying the compound activates c-Met misstate even the proposed mechanism. And the specific evidence for that binding, including the widely quoted picomolar affinity figure, comes from work that has since been retracted.
Evidence Integrity and What Survives It. Two papers from the originating Washington State University laboratory were retracted in 2025 after an institutional investigation found falsified or fabricated figures, and a third has carried an expression of concern since 2021. The retracted pair is the source of the HGF binding affinity figure. The separate and frequently repeated claim that Dihexa is seven orders of magnitude more potent than BDNF originates in a 2011 paper that carries an expression of concern but has not been retracted; the figure referred to picomolar activity in a cell-culture spinogenesis assay rather than potency in any general sense. Independent work published since does not depend on any of them. A 2021 study in APP/PS1 mice reported restored spatial learning, preserved neuronal density, increased synaptophysin expression and reduced glial activation over three months of oral administration, attributing the effect to PI3K/AKT signalling — without replicating the HGF binding data, and framing the mechanism through an angiotensin IV axis instead. Researchers evaluating this compound should read the retraction notices alongside the original citations.
Cognitive and Neuronal Models. Published preclinical work spans scopolamine-induced impairment models, aged rodents and transgenic Alzheimer's models, with endpoints including spatial memory tasks, dendritic spine density, synaptic markers and markers of glial activation. All of it is animal or cell-culture work. No human clinical trial of Dihexa has been published. The nearest human data in the same pathway class comes from a different molecule — fosgonimeton, developed by a company founded to commercialise this research programme and described by that company as a prodrug converted in plasma to an active metabolite. Its Phase 2/3 Alzheimer's trial failed its primary endpoint in 2024 and development was discontinued. That result is context for the pathway, not evidence about Dihexa.
Pathway Considerations for Handling. The HGF/c-Met axis is among the better-characterised oncogenic signalling pathways in the cancer literature. Institutional risk assessment should govern handling of any compound proposed to act on it, alongside the manufacturer's own safety documentation.
Researchers should evaluate each publication according to its model, species, vehicle, dose route and endpoints, and should check the current status of any paper cited for mechanism.
Analytical quality matters for any research material, because impurities, degradation products, incorrect identity or an unclear mass basis introduce uncontrolled variables. For Dihexa the relevant analytics are small-molecule analytics, and three considerations are specific to this compound in solid form.
Identity confirmation should not rest on peptide logic. The molecule has two residues and two synthetic caps; there is no sequence to confirm. What answers the question is chromatographic purity against a reference standard with the method stated, a mass result near 504.7 consistent with C₂₇H₄₄N₄O₅, and structural confirmation by NMR where the manufacturer provides it. Given that published molecular data for Dihexa is inconsistent across commercial sources, the reference figures used for comparison matter as much as the result.
The mass basis of the fill is a specification in its own right. Residual counterion and hydration both affect what fraction of a weighed solid is Dihexa, and both affect the volume of solvent required to reach a target concentration. This is a question for the certificate of analysis.
Solid form keeps characterisation options open. Appearance, melting point, elemental composition and NMR are all available on a solid. Where a manufacturer provides them, they add independent confirmation that a chromatographic purity figure alone does not.
Researchers should assess, where applicable:
No certification, regulatory approval or quality claim should be inferred unless explicitly documented by the manufacturer or a relevant regulatory authority. Sitewide catalog statements are not a substitute for lot-specific documentation.
Storage and handling. Requirements should be determined from the current Dihexa product documentation and lot-specific instructions. A solid has different handling requirements from a prepared solution, and from the aqueous peptide preparations that make up most of this catalogue.
General laboratory considerations include:
Storage guidance should not be inferred from another supplier's preparation, from a prepared-solution format, or from the catalogue's peptide products, because physical form and packaging determine the relevant behaviour.
Shipping. Helix Bio's website describes research materials as being supplied to laboratories and institutions in the United States and describes tracked shipping and cold-chain handling within its fulfillment process. Because shipping conditions, packaging specifications, availability and delivery requirements may change, researchers should review the current Helix Bio shipping information and product listing before ordering. Product packaging should remain appropriately labelled and handled as research material after delivery. Researchers are responsible for following applicable institutional, federal, state and local requirements governing research materials.
Dihexa is sold by Helix Bio for research and laboratory purposes only. It is not intended for human or veterinary consumption, self-administration, ingestion, injection, nasal administration, any other form of administration, or the diagnosis, treatment, cure, mitigation or prevention of any disease or medical condition.
Dihexa is not an FDA-approved drug in the United States and has never entered human clinical trials. No cognitive, memory, neurological or therapeutic benefit is claimed or implied. Published findings describe animal and cell-culture experiments and do not establish outcomes in humans.
Part of Dihexa's published mechanistic literature has been formally retracted following a research-integrity investigation, and a further paper carries an expression of concern. Researchers should verify the current status of any publication before relying on it.
Dihexa-related bulk drug substances were removed from 503A Category 2 in April 2026 as a procedural step for further evaluation, and dihexa acetate is scheduled for consideration at a Pharmacy Compounding Advisory Committee meeting before the end of February 2027. Removal from a category is not authorisation to compound, and an advisory recommendation is not an approval.
This product is not a dietary supplement, consumer wellness product or medical treatment. Researchers are responsible for determining whether a material is appropriate for their intended experimental application and for complying with applicable institutional and regulatory requirements.
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