An Investigation of Quorum Sensing Inhibitors against in The Endophytic Fungus of the sp.

, a common food-borne pathogen, forms biofilms and generates virulence factors through a quorum sensing (QS) mechanism. In this study, six compounds (dankasterone A, demethylincisterol A, zinnimidine, cyclo-(L-Val-L-Pro), cyclo-(L-Ile-L-Pro), and cyclo-(L-Leu-L-Pro)) were isolated from the endophytic fungus of the sp. in the South China Sea. Among them, demethylincisterol A, a sterol derivative, exhibited strong QS inhibitory activity against . The QS inhibitory activity of demethylincisterol A was evaluated through experiments. The minimum inhibitory concentration (MIC) of demethylincisterol A against was 6.25 μg/mL. At sub-MIC concentrations, it significantly decreased biofilm formation, hindered mobility, and diminished the production of protease and hemolysin activity. Moreover, RT-qPCR results demonstrated that demethylincisterol A markedly inhibited the expression of QS-related genes ( and ) in . The exposure to demethylincisterol A3 resulted in the downregulation of genes (, , , , , , , and ) associated with biofilm formation, mobility, and virulence factors. Hence, demethylincisterol A is a potentially effective compound in the pipeline of innovative antimicrobial therapies.