Screening of compounds against intestinal pathogenic bacteria and exploration of their mechanisms of action

Colorectal cancer (CRC) poses a serious threat to human life and health. The intestinal pathogenic bacteria Fusobacterium nucleatum (Fn) and enterotoxigenic Bacteroides fragilis (ETBF) are closely associated with the occurrence and progression of CRC. The development of novel compounds targeting Fn and ETBF holds significant clinical importance for the treatment of CRC. In this study, broth microdilution method was employed to screen 3 400 compounds in a compound library for in vitro antibacterial activity against the two bacteria. Using a criterion of MIC₅₀ ≤ 64 μg·mL^-1, 52 compounds with anti-Fn activity and 44 compounds with anti-ETBF activity were identified. Among them, compound G7 exhibited the best inhibitory activity against both two bacteria (Fn, MIC₅₀ = 1 μg·mL^-1; ETBF, MIC₅₀ = 4 μg·mL^-1) and could effectively inhibit the migration of colorectal cancer cells by inhibiting bacteria. Preliminary mechanistic studies revealed that G7 exerts its antibacterial effects by inhibiting biofilm formation and the expression of multiple genes related to adhesion and hyphal formation.