Antimicrobial activity of Zanthoxylum nitidum (Roxb.) DC. extract against the gastric pathogen Helicobacter pylori

Helicobacter pylori (H. pylori) is a Gram-negative bacterium that infects half of the global population and contributes to various gastric diseases, including peptic ulcers and gastric cancer. The increasing prevalence of antimicrobial resistance necessitates the development of alternative therapeutic strategies. Traditional medicinal plants have long been used to treat gastrointestinal disorders and may offer promising anti-H. pylori potential. In this study, eleven medicinal plants from Manipur, India, were screened for antimicrobial activity against H. pylori by determining their minimum inhibitory concentrations (MICs). The most potent extract was further tested against Escherichia coli and Bacillus subtilis, its effects on H. pylori morphology using scanning electron microscopy, and cytotoxicity on cancerous and non-cancerous cells. Metabolite profiling and molecular docking were used to identify bioactive compounds and predict their target interactions. Zanthoxylum nitidum (Roxb.) DC exhibited the strongest activity against both drug‑sensitive and resistant H. pylori, with minimal cytotoxicity. No inhibitory effect was observed against E. coli or B. subtilis at the MIC, suggesting selective activity against H. pylori. SEM revealed morphological changes in treated H. pylori cells, including surface distortions and coccoid transformation. In AGS cells, the extract significantly reduced the percentage of cells displaying the H. pylori-induced hummingbird phenotype. Metabolite profiling identified alkaloids and flavonoids, while docking studies showed high‑affinity binding of quercetin, zanthomuurolanine, and hesperidin to HpUreI, a proton‑gated urea channel, suggesting interference with acid resistance mechanisms. These findings demonstrate the selective in vitro efficacy of Z. nitidum against H. pylori and support further in vivo investigation of its potential as a plant‑based therapeutic for H. pylori‑associated gastric diseases.