In vitro Antibiofilm Activity-directed In silico Identification of Natural Products Targeting Bacterial Biofilm Regulators SarA and LasR.

Background: Antibiofilm agents serve as an essential tool in the fight against antibiotic resistance, and natural products provide a promising source for potential drug leads.

Objective: This study investigates the activity of twenty Bangladeshi medicinal plants against Staphylococcus aureus and Pseudomonas aeruginosa biofilms and predicts the interactions of selected phytochemicals from five of the best performing plants with the active sites of transcriptional regulatory proteins SarA of S. aureus and LasR of P. aeruginosa.

Methods: The plant extracts were tested by microtiter plate-based assay against S. aureus and P. aeruginosa biofilms. Molecular docking and molecular dynamics simulation (MD) were conducted using PyRx and GROMACS, respectively.

Results: The best activity was identified for Cassia fistula and Ananas comosus, showing ≥ 75% inhibition of biofilm formation. ent-Epicatechin-(4α→8)-epiafzelechin (EEE) of C. fistula, cyanidin-3,3',5-tri-O-β-D-glucopyranoside (CTG) of A. comosus, and 7-O-(4-hydroxy-Ecinnamoyl)- spinoside of A. spinosus showed the best predictive binding affinity (-7.6, -7.6 and - 7.7 kcal/mol, respectively) for SarA. EEE was the only ligand to exhibit a stable ligand-protein complex with SarA in the MD simulation of 200 ns (binding energy of MMPBSA analysis - 39.899 kJ/mol). Chrysophanol, epicatechin and physcion, of C. fistula (-10.5, -10.5, and -11.0 kcal/mol, respectively) and auraptene of F. limonia (-10.8 kcal/mol) showed the best predictive binding affinity for LasR. Epicatechin showed the most stable ligand-protein complex with LasR (binding energy of MMPBSA analysis -63.717 kJ/mol).

Conclusion: Epicatechin and its derivative EEE could be used as scaffolds for the d evelopment of new antibiofilm agents against P. aeruginosa and S. aureus, respectively.