Sulfisoxazole

Sulfisoxazole (CAS No.: 127-69-5) is an orally active sulfonamide antibacterial agent that has also been characterized as a selective endothelin receptor antagonist, exhibiting greater potency toward the endothelin receptor A (ETA) subtype than endothelin receptor B (ETB). Beyond its established antimicrobial activity, sulfisoxazole modulates endothelin-mediated signaling pathways through specific receptor binding, with inhibitory activity observed in the low micromolar range for ETA and weaker activity toward ETB. Recent studies highlight its emerging role in cancer biology, where it interferes with ETA-dependent processes, including the regulation of precursor mRNA splicing and the suppression of exosome biogenesis and release in breast cancer cell models, suggesting potential utility in tumor progression and intercellular communication studies. These dual pharmacological properties position sulfisoxazole as a useful tool compound in investigations of endothelin signaling, exosome-mediated pathways, and drug repurposing strategies, with experimental concentrations typically optimized according to specific cellular or in vivo research designs.