2. Academic Validation
  3. Small molecule inhibitors of intestinal epithelial anion exchanger SLC26A3 (DRA) with a luminal, extracellular site of action

Small molecule inhibitors of intestinal epithelial anion exchanger SLC26A3 (DRA) with a luminal, extracellular site of action

  • Eur J Med Chem. 2023 Mar 5;249:115149. doi: 10.1016/j.ejmech.2023.115149.
Onur Cil 1,  Marc O Anderson 2,  Livia de Souza Goncalves 3,  Joseph-Anthony Tan 4,  Peter M Haggie 4,  Alan S Verkman 4
Affiliations

Affiliations

  • 1 Department of Pediatrics, University of California San Francisco, San Francisco, CA, USA. Electronic address: [email protected].
  • 2 Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, CA, USA.
  • 3 Department of Pediatrics, University of California San Francisco, San Francisco, CA, USA.
  • 4 Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA, USA.
PMID: 36724632 DOI: 10.1016/j.ejmech.2023.115149
Abstract

The anion exchanger protein SLC26A3 (down-regulated in adenoma, DRA) is expressed in the luminal membrane of intestinal epithelial cells in colon, where it facilitates the absorption of Cl- and oxalate. We previously identified a 4,8-dimethylcoumarin class of SLC26A3 inhibitors that act from the SLC26A3 cytoplasmic surface, and demonstrated their efficacy in mouse models of constipation and hyperoxaluria. Here, screening of 50,000 new compounds and 1740 chemical analogs of active compounds from the primary screen produced five novel classes of SLC26A3-selective inhibitors (1,3-dioxoisoindoline-amides; N-(5-sulfamoyl-1,3,4-thiadiazol-2-yl)acetamides; thiazolo-pyrimidin-5-ones; 3-carboxy-2-phenylbenzofurans and benzoxazin-4-ones) with IC50 down to 100 nM. Kinetic washout and onset of action studies revealed an extracellular site of action for the thiazolo-pyrimidin-5-one and 3-carboxy-2-phenylbenzofuran inhibitors. Molecular docking computations revealed putative binding sites for these inhibitors. In a loperamide model of constipation in mice, orally administered 7-(2-chloro-phenoxymethyl)-3-phenyl-thiazolo [3,2-a]pyrimidin-5-one (3a) significantly increased stool weight, pellet number and water content. SLC26A3 inhibitors with an extracellular site of action offer the possibility of creating non-absorbable, luminally acting inhibitors with minimal systemic exposure following oral administration. Our findings also suggest that inhibitors of related SLC26 anion transporters with an extracellular site of action might be identified for pharmacological modulation of selected epithelial ion transport processes.

Keywords

Constipation; Down-regulated in adenoma; Kidney stones; Non-absorbable drugs; SLC26.

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