Indole-3-carbinol induces apoptosis-like death in Escherichia coli on different contribution of respective reactive oxygen species

Aims: Indole-3-carbinol (I3C) is a natural compound derived from brassica vegetables, displaying antibacterial activity. The study aims to elucidate the antibacterial mode of action(s) induced by indole-3-carbionol in Escherichia coli and enhance the understandings on the respective contribution of each reactive oxygen species (ROS), superoxide anion (O₂⁻), hydrogen peroxide (H₂O₂), hydroxyl radical (OH⁻) during the process. Main methods: The antibacterial activity of I3C was assessed through kinetic assay. The generation of ROS was measured by flow cytometer using H₂DCFDA dye, while further analysis of respective contribution was done through application of each scavenger: tiron, thiourea and sodium pyruvate. DNA fragmentation and chromatin condensation were observed by TUNEL and DAPI staining agent. Finally, Annexin V/PI, FITC-VAD-FMK and DiBAC₄(3) was applied for detection of apoptosis-like death. Key findings: I3C exhibited antibacterial activity in E. coli through accumulation of ROS and DNA damage, eventually leading to apoptosis-like death. Contribution of each ROS displayed respective manner, OH⁻ exerting the most potent influence whereas O₂⁻ showed least impact. Significance: Our study is the first to link I3C to the bacterial apoptosis-like death and displays the potential of this agent as a candidate for potential drugs that could help regulating the E. coli, an opportunistic human pathogen. Moreover, the study focused on investigating the individual contribution of each ROS during the process, trying to enhance the understanding regarding ROS and cellular processes followed by oxidative stress in bacteria.