Repurposing the Natural Product Maslinic Acid for Combating Clostridioides difficile Infections

Clostridioides difficile infection remains a leading cause of healthcare-associated diarrhea, and treatment options remain constrained by frequent recurrence and disruption of the intestinal microbiota. Natural products with selective antibacterial activity may provide new therapeutic opportunities for C. difficile. In this study, the pentacyclic triterpene maslinic acid, a naturally occurring compound abundant in olives and olive-derived products, was evaluated for its antibacterial activity against C. difficile. Maslinic acid inhibited a diverse panel of clinical isolates, including hypervirulent strains, with MIC values of 8-16 μg/mL while exhibiting substantially weaker activity against representative commensal gut bacteria. Time-kill studies demonstrated complete elimination of detectable C. difficile within 2 h of treatment, indicating rapid bactericidal activity. Additionally, its antibacterial potency was preserved when tested at high bacterial inoculum and following prolonged exposure to simulated gastric and intestinal fluids, suggesting favorable stability under gastrointestinal conditions. Maslinic acid also showed no cytotoxicity to Caco-2 cells at concentrations substantially exceeding its MICs. Mechanistic studies further indicated that maslinic acid preferentially interfered with protein and lipid biosynthetic pathways without evidence of membrane disruption. Moreover, evaluation of structurally related pentacyclic triterpenes identified several analogs with comparable activity with maslinic acid and highlighted structural features associated with antibacterial potency. Collectively, these findings identify maslinic acid as a selective, rapidly bactericidal natural product with characteristics that support its continued investigation as a potential therapeutic candidate for C. difficile infections.