Cosmopolitan but still untapped: Antimicrobial, antibiofilm and in silico molecular docking study on Caulerpa racemosa, Dictyopteris polypodioides and Padina pavonica

Abstract

Egyptian seaweeds contain diverse bioactive compounds, but our understanding of their antimicrobial potential, particularly against multidrug-resistant (MDR) human pathogens, is still limited and underestimated. This study screened the antimicrobial potential of ethanolic extracts of Caulerpa racemosa , Dictyopteris polypodioides , and Padina pavonica against various MDR bacterial and fungal strains using broth microdilution technique. Antibiofilm assay of the seaweed extracts against Pseudomonas aeruginosa clinical isolates was also investigated. Our findings showed that the minimum inhibitory concentrations (MICs) of the tested seaweed extracts ranged between 62 and 500 μg mL −1 . P. pavonica displayed the most biofilm inhibition percentages against P. aeruginosa clinical isolate by 31.2 % and 62.5 % for BIC 50 and BIC 90 , respectively, as comparing to D. polypodioides and C. racemosa . Liquid chromatography-high resolution electrospray ionization mass spectrometry (LC-HR-ESI-MS) metabolic profiling of P. pavonica ethanolic extract was characterized. Twenty-seven metabolites were identified and checked for their inhibitory biofilm formation based on molecular docking simulation on LasR protein-specific quorum sensing. Interestingly, squalene (4) , hydroperoxy-24 vinyl-24 cholesterol (18) , fucoxanthol (21) , flavoxanthin (22) , and fucoxanthin (23) exhibited adequate interaction energies and formed significant interactions inside the LasR active site, supporting them to possess potent antibiofilm properties. Overall, P. pavonica can be recommended as powerful agent of antibiofilm preparation. • Antimicrobial potential of the Egyptian seaweeds Caulerpa racemosa , Dictyopteris polypodioides and Padina pavonica were investigated. • Antibiofilm assays of their ethanolic extracts against P. aeruginosa clinical isolates were conducted. • P. pavonica ethanolic extract was the most effective one. • Twenty-seven metabolites in P. pavonica extract were identified using LC-HR-ESI-MS technique. • Molecular docking of these metabolites was simulated.