Discovery of 1,3,4-Thiadiazole Sulfonamide-Based Potent Inhibitors against the Unsaturated Fatty Acid Synthase FabX of <i>Helicobacter pylori</i>

Unsaturated fatty acids (UFAs) are essential for the membrane function in most bacteria. In <i>Helicobacter pylori</i> (<i>H. pylori</i>), a gastric pathogen, UFA biosynthesis depends on the bifunctional dehydrogenase/isomerase FabX, a promising target against <i>H. pylori</i>. Herein, we report the first FabX inhibitor, <b>P61G11</b> (compound <b>1</b>, IC₅₀ = 3.7 ± 0.2 μM), identified via high-throughput screening and featuring a 1,3,4-thiadiazole sulfonamide scaffold. The costructure of FabX-<b>1</b> reveals occupancy of the L-shaped substrate-binding tunnel via hydrophobic interactions and hydrogen bonds. Structure-based optimization led to more potent derivatives, among which compound <b>47</b> showed potent inhibition (IC₅₀ = 0.128 ± 0.002 μM), representing a 29-fold improvement. Compound <b>47</b> also demonstrated strong <i>in vitro</i> antibacterial activity (MIC = 0.5-1 μg/mL), when combined with membrane permeabilizers, efflux pump inhibitors, and clarithromycin, and exhibited narrow-spectrum efficacy against <i>H. pylori</i>, providing a novel strategy for anti-<i>H. pylori</i> therapy.