Metabolomic fingerprinting, molecular modelling and experimental bioprospection of Helianthus annuus seed cultivars as Pseudomonas aeruginosa LasR modulators

Abstract

The Pseudomonas aeruginosa LasR quorum sensing system (QSS) is central to regulating the expression of several pathogenicity factors. Also, while seed- and/or plant-derived products have been investigated as QSS regulators, the impact of Helianthus annuus (Pannar sunflower seed cultivars) extracts and metabolites as LasR modulators remain underexplored. Thus, this study focused on the untargeted metabolomic profiling (Liquid Chromatography-Mass Spectrometry), in vitro and in silico (docking, pharmacokinetics, dynamic simulation) bioprospection of Pannar seed cultivars' extracts and metabolites as LasR modulators. The extracts showed significant QS modulating properties (motility, violacein, biofilm, cell attachment, pyocyanin inhibition) with the PAN 7102 CLP seed cultivar (74.3 %) being the most potent, compared to azithromycin (65 %) and cinnamaldehyde (62 %). Chemometric principal component analysis (PCA) analysis showed distinct metabolite signatures with 52.5 % variance across the six cultivars that was driven by aqueous and ethanolic extracts of PAN 7102, 7160, and 7156 cultivars. The presence of methoxymellein, hydroxytetradecanedioic acid, koninginin G, geoside, pinellic acid and methylpicraquassioside A were reported for the first time. The profiled metabolites were subjected to a 100-ns molecular dynamics simulation following molecular docking. Binding free energy (ΔG_bind) calculations revealed obolactone (-48.26 kcal/mol), 1,4-bis(phenylglyoxaloyl)benzene (-45.06 kcal/mol), cyclocanaliculatin (-43.41 kcal/mol), 5-hydroxy-7-methoxy-2-phenylchroman-4-one (-39.18 kcal/mol) and lonchocarpin (-33.78 kcal/mol) as first-time putative leads relative to azithromycin (-32.09 kcal/mol). All lead metabolites also conformed to Lipinski's rule of 5 (Ro5), and their LasR bound complexes were thermodynamically stable and compact given their strong bond interactions. Findings indicate that metabolomic profiling remain key to identifying new compounds from underexplored species. H. annuus lead metabolites and extracts may also play key roles as LasR modulators. Further structural modification of the 5 leads could aid their development into novel, oral therapeutics targeting LasR to mitigate resistant P. aeruginosa infections.