Inhibitory effects of isobavachalcone against Tetrahymena thermophila: Mechanistic insights

Isobavachalcone (IBC), a bioactive flavonoid derived from Psoralea corylifolia, exhibits potent anti-ciliate activity, but its underlying mechanism remains unclear. Utilizing Tetrahymena thermophila as a model organism, we demonstrated that IBC induces dose-dependent mortality (12 h-IC₅₀: 1.39 mg/L) and inhibits growth. Mechanistically, IBC triggers oxidative stress by elevating reactive oxygen species (ROS) and disrupting antioxidant enzymes, including superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione (GSH). This disruption leads to membrane damage, as evidenced by lactate dehydrogenase (LDH) leakage and ATPase inhibition, as well as mitochondrial dysfunction. Microscopic examination and staining confirmed that cell death occurs via necrotic cell death rather than apoptosis. Transcriptome analysis revealed key pathways, including peroxisome-mediated oxidation, glutathione metabolism, and ATP-binding cassette (ABC) transporters, further supporting the role of IBC in oxidative and structural disruption. These findings elucidate the anti-ciliate mechanism of IBC, providing valuable insights for developing targeted anti-parasitic agents.