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Larazotide (AT-1001)
Larazotide is a synthetic octapeptide, Gly-Gly-Val-Leu-Val-Gln-Pro-Gly, derived from the zonula occludens toxin of Vibrio cholerae. It is the reference antagonist of the zonulin pathway, the endogenous signalling route that loosens epithelial tight junctions, and it occupies an unusual position among barrier-function tools: rather than disrupting junctions to study what happens, it blocks their disassembly, which lets an experiment ask whether barrier loss is a cause of a downstream effect or merely a consequence of it.
Two properties make it practical in the laboratory. It acts locally at the luminal surface rather than systemically, and it is not appreciably absorbed, so its effect can be attributed to the epithelium it contacts. That locality is the point: it isolates the barrier variable from the systemic ones that usually travel with it.
Technical Specifications
| Property | Specification |
|---|---|
| Product Name | Larazotide |
| Synonyms | AT-1001, INN-202, FZI/0 |
| Sequence | Gly-Gly-Val-Leu-Val-Gln-Pro-Gly |
| CAS Number | 258818-34-7 |
| Molecular Formula | C₃₂H₅₅N₉O₁₀ |
| Molecular Weight | 725.8 g/mol |
| Salt Form | Acetate |
| Chemical Class | Synthetic octapeptide; zonulin receptor antagonist |
| Molecular Target | Zonulin pathway / tight junction regulation |
| Appearance | White to off-white lyophilized powder |
Research Applications & Mechanism of Action
Zonulin signalling triggers rearrangement of the actin cytoskeleton and displacement of tight junction proteins from the cell-cell contact, opening the paracellular route. Larazotide antagonises that signal, so junction proteins stay where they are and paracellular permeability is preserved. The readouts are correspondingly physical rather than biochemical: transepithelial electrical resistance, flux of an inert marker such as labelled dextran, and the distribution of occludin and ZO-1 by immunofluorescence.
Primary fields of in vitro and preclinical laboratory investigation include:
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Barrier Integrity Assays: Measuring transepithelial electrical resistance and paracellular tracer flux in polarised epithelial monolayers.
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Tight Junction Protein Localisation: Imaging occludin, claudin and ZO-1 distribution after a permeability challenge, with and without antagonist present.
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Barrier-Autoimmunity Models: Testing whether preserving epithelial integrity alters the transition from asymptomatic autoimmunity to inflammatory disease in animal models.
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Zonulin Pathway Mapping: Serving as the standard pharmacological block for attributing an observed permeability change to zonulin rather than to another mechanism.
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Analytical Reference Work: A defined octapeptide standard for chromatographic and mass-spectrometric method development.
Selected Research Literature
Peer-reviewed literature indexed on PubMed, provided for scientific context only. Nothing here describes or implies a use for this material.
- Tajik N, Frech M, Schulz O, et al. Targeting zonulin and intestinal epithelial barrier function to prevent onset of arthritis. Nat Commun. 2020;11(1):1995. doi:10.1038/s41467-020-15831-7
- Troisi J, Venutolo G, Terracciano C, Delli Carri M, Di Micco S, Landolfi A, Fasano A. The therapeutic use of the zonulin inhibitor AT-1001 (larazotide) for a variety of acute and chronic inflammatory diseases. Curr Med Chem. 2021;28(28):5788-5807. doi:10.2174/0929867328666210104110053
Assay note. Tajik et al. used barrier restoration as an intervention in the pre-symptomatic window rather than after disease onset. Timing is therefore a design variable in its own right for this compound, and a null result obtained after barrier loss has already occurred says little about the pathway.
Analytical Documentation
Purity, identity, and composition vary by manufacturing lot. Kimera Chems does not publish a single fixed purity figure for this item; refer to the batch-specific Certificate of Analysis (COA) issued for the lot received, which reflects third-party analytical testing for that lot. Contact us if a COA for your lot is required.
Related Research Compounds
Research Use Disclaimer
Research Use Only Disclaimer: This product is developed and distributed strictly as a Research Use Only (RUO) laboratory reference chemical intended exclusively for non-clinical analytical and scientific investigation. It is not an FDA-approved drug, medical treatment, dietary supplement, or food ingredient, and is strictly prohibited for human or animal consumption. Kimera Chems supplies this research material solely to qualified institutions and professional investigators for authorized laboratory research.
