Zonulin; paracellular permeability and apical-basolateral polarity
Larazotide Acetate targets tight junctions in the intestinal epithelium. It is a peptide antagonist of α3β4 subunit-containing nicotinic acetylcholine receptors (nAChRs). It selectively inhibits epibatidine-induced calcium mobilization in HEK293 cells expressing human α3β4 nAChRs over α4β2 nAChRs (IC50s = 91 and 276 nM, respectively). By modulating tight junctions, it reduces intestinal permeability.

On Vero cell proliferation, larazotideacetate (1-100μM; 5 days) had an effect [1]. The varicella zoster virus (VZV) can be inhibited by larazotide acetate (1-100 μM; 3 d); the EC50 values for the OKA strain and the 07-1 strain, respectively, are 44.14 and 59.06 μM [1]. In Caco-2 cells, larazotideacetate (1 and 3 mM; 72 hours) reduces the permeability of tight junctions caused by cytokines [2]. In IEC6 cells, PTG-induced ZO-1 translocation and actin cytoskeleton rearrangement are inhibited by larazotideacetate (12.5 mM; 1 h) [2].
In vitro, Larazotide acetate inhibits the passage of a gliadin 13-mer peptide across Caco-2 cell monolayers. It acts as a tight junction regulator. It selectively inhibits epibatidine-induced calcium mobilization in cells expressing α3β4 nAChRs.

Larazotide acetate (250 μg; intraperitoneally injected twice weekly for 7 weeks) inhibits intestinal permeability in gluten-sensitive transgenic mice [1].
In vivo, Larazotide acetate is being developed for the treatment of celiac disease. It works by modulating tight junctions in the intestinal lining, reducing gluten permeability and subsequent inflammation. It is also being investigated for the treatment of inflammatory bowel disease.

The recombinant SARS-CoV-2 Mpro (Proteros) (20 nM at a final concentration) was mixed with serial dilutions of AT1001 and Dabcyl-KTSAVLQSGFRKM-E(Edans)-NH2 substrate (5 μM) in 20 μL (reaction volume) assay buffer solution (20 mM HEPES, pH 7.5, 1 mM DTT, 1 mM EDTA, 100 mM NaCl, 0.01% Tween20). The appropriate volume of substrate was added in reaction buffer along with 42.5 nL compound in 100% DMSO. Finally, the appropriate volume of target enzyme was added, and the reaction started with an incubation time of 10 min. The fluorescence signal of the Edans was monitored at an emission wavelength of 500 nm by exciting at 360 nm, by means of Pherastar FSX microplate Reader. Calpeptin was used as reference to set up the experiments[1].
The activity of Larazotide acetate can be assessed using cell-based assays with Caco-2 cell monolayers. The passage of a fluorescently labeled tracer or a gliadin peptide across the monolayer is measured in the presence of varying concentrations of the compound. The IC50 for inhibition of permeability is determined from dose-response curves. Its binding to α3β4 nAChRs can be assessed using radioligand binding or calcium mobilization assays.

Cytotoxicity assay [1]
Cell Types: Vero cell line
Tested Concentrations: 1-100 μM
Incubation Duration: 5 days
Experimental Results: Inhibited Vero cell growth, CC50 value was 82.5 μM.
To evaluate the cellular effects of Larazotide acetate, intestinal epithelial cells (e.g., Caco-2) are treated with the compound. Tight junction integrity is assessed by measuring transepithelial electrical resistance (TEER) and paracellular permeability. The expression and localization of tight junction proteins such as occludin and zonula occludens are assessed by immunofluorescence.

Animal/Disease Models: HLA-HCD4/DQ8 double transgenic mice [2]
Doses: 250 μg
Route of Administration: intraperitoneal (ip) injection; 250 μg twice a week for 7 weeks
Experimental Results: Barrier function parameters improved, macrophages in lamina propria Cell count diminished to control levels.
In vivo studies with Larazotide acetate typically involve oral administration to animal models or human subjects. In models of celiac disease, the compound's effects on intestinal permeability, inflammation, and gluten-induced damage are assessed. Its safety and efficacy are evaluated in clinical trials.

Larazotide Acetate has a molecular formula of C34H59N9O12 and a molecular weight of 785.89 g/mol. Its CAS number is 881851-50-9. It is a peptide-based drug. It is soluble in water (≥20 mg/mL). The purity is typically ≥95%. It should be stored according to the manufacturer's instructions.

Specific toxicology data for Larazotide acetate are not extensively detailed in the available literature. However, as a drug under clinical investigation, it has undergone safety evaluations. It is generally well-tolerated. As with all research compounds, standard safety precautions should be taken when handling Larazotide acetate.

[1]. Peptide Derivatives of the Zonulin Inhibitor Larazotide (AT1001) as Potential Anti SARS-CoV-2: Molecular Modelling, Synthesis and Bioactivity Evaluation. Int J Mol Sci. 2021 Aug 30;22(17):9427.

[2]. Larazotide acetate regulates epithelial tight junctions in vitro and in vivo. Peptides. 2012 May;35(1):86-94.

novel coronavirus, namely severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been identified as the pathogen causing a severe and rapidly developing pneumonia (COVID-19) outbreak. The virus’s enzyme, called 3CLpro or main protease (Mpro), is crucial for viral replication, making it a promising target for antiviral drug development. Recently, we have used a drug repositioning strategy to demonstrate that the zonulin octapeptide inhibitor AT1001 (lalazolyl acetate) can bind to the Mpro catalytic domain, thus rapidly responding to the global COVID-19 pandemic. Therefore, in this study, we attempted to investigate the antiviral activity of AT1001 and its five derivatives through cell-based experiments. Our results identified the molecular framework of the AT1001 peptide, which can be used for lead compound optimization to develop a new generation of SARS-CoV-2 antiviral drugs with higher bioactivity and improve the success rate of clinical trials. [1]

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Tight junctions (TJs) control the paracellular permeability and apical-basal lateral polarity of epithelial cells and can be regulated by exogenous and endogenous stimuli. Permeability dysregulation is associated with a variety of pathological conditions, such as celiac disease and inflammatory bowel disease. This study investigated the mechanism by which laprazole peptide acetate (an octapeptide and a tight junction regulator) inhibits cellular changes induced by gliadin fragments, AT-1002, and cytokines. We previously demonstrated that the hexapeptide AT-1002, derived from the Vibrio cholerae tight junction toxin ZOT, induces various biochemical changes in IEC6 and Caco-2 cells, leading to decreased transepithelial electrical resistance (TEER) and increased tight junction (TJ) permeability. This study found that laprazole peptide acetate inhibits the redistribution and rearrangement of tight junction protein-1 (ZO-1) and actin induced by AT-1002 and gliadin fragments in Caco-2 and IEC6 cells. Functionally, laprazole peptide acetate inhibits AT-1002-induced TEER reduction and TJ opening in Caco-2 cells. In addition, laprazole acetate inhibited the translocation of gliadin 13 peptide associated with celiac disease on the Caco-2 cell monolayer. Furthermore, apical application of laprazole acetate inhibited the increase in tight junction permeability induced by cytokine application on the basolateral side. Finally, in in vivo experiments in gliadin-sensitized HLA-HCD4/DQ8 double transgenic mice, laprazole acetate inhibited gliadin-induced intestinal macrophage aggregation and maintained normal tight junction structure. In summary, our data suggest that laprazole acetate can inhibit the changes induced by AT-1002, gliadin, and cytokines in epithelial cells and maintain the structure and function of tight junctions in vitro and in vivo. [2]
Larazotide acetate is a peptide-based tight junction regulator under investigation for the treatment of celiac disease. It reduces intestinal permeability and subsequent inflammation. It is also a peptide antagonist of α3β4 nAChRs. It is a research tool for studying intestinal permeability, tight junctions, and celiac disease.

C34H59N9O12

785.9

785.428

C, 51.96; H, 7.57; N, 16.04; O, 24.43

881851-50-9

Larazotide;258818-34-7

44146842

White to off-white solid powder

3.736

10

13

21

55

1320

5

CC(C)C[C@@H](C(=O)N[C@@H](C(C)C)C(=O)N[C@@H](CCC(=O)N)C(=O)N1CCC[C@H]1C(=O)NCC(=O)O)NC(=O)[C@H](C(C)C)NC(=O)CNC(=O)CN.CC(=O)O

NYGCNONRVCGHAT-UFIKZEAMSA-N

InChI=1S/C32H55N9O10.C2H4O2/c1-16(2)12-20(38-30(49)26(17(3)4)39-24(44)14-35-23(43)13-33)28(47)40-27(18(5)6)31(50)37-19(9-10-22(34)42)32(51)41-11-7-8-21(41)29(48)36-15-25(45)461-2(3)4/h16-21,26-27H,7-15,33H2,1-6H3,(H2,34,42)(H,35,43)(H,36,48)(H,37,50)(H,38,49)(H,39,44)(H,40,47)(H,45,46)1H3,(H,3,4)/t19-,20-,21-,26-,27-/m0./s1

2-[[(2S)-1-[(2S)-5-Amino-2-[[(2S)-2-[[(2S)-2-[[(2S)-2-[[2-[(2-aminoacetyl)amino]acetyl]amino]-3-methylbutanoyl]amino]-4-methylpentanoyl]amino]-3-methylbutanoyl]amino]-5-oxopentanoyl]pyrrolidine-2-carbonyl]amino]acetic acid Acetate

Larazotide Acetate; AT-1001; AT 1001; AT1001;Larazotide acetate; 881851-50-9; Larazotide (acetate); AT-1001; Larazotide acetate [USAN]; Larazotide acetate (USAN); UNII-FO8S2IW40N;

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O : ~16.67 mg/mL (~21.21 mM)
DMSO : ~3.2 mg/mL (~4.07 mM)

Solubility in Formulation 1: 100 mg/mL (127.24 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with sonication.

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 (Please use freshly prepared in vivo formulations for optimal results.)