Identification of potential natural products derived from fungus growing termite, inhibiting Pseudomonas aeruginosa quorum sensing protein LasR using molecular docking and molecular dynamics simulation approach

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

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 (ΔGbind) 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.

Identification of the myxobacterial secondary metabolites Aurachin A and Soraphinol A as promising inhibitors of thymidylate kinase of the Monkeypox virus

Thymidylate kinase (TMPK) of monkeypox virus (MPXV) has emerged as a promising target for potential therapeutics due to its significant role in pyrimidine metabolism. While smallpox drugs are advised for treating monkeypox, the European Medicine Agency has sanctioned Tecovirimat due to its potent nanomolar activity. Nonetheless, there is a need for monkeypox-specific therapeutic options. In this work, we employed docking-based virtual screening and molecular dynamics (MD) simulations to identify myxobacterial secondary metabolites as promising anti-viral natural compounds capable of inhibiting thymidylate kinase. The computational pharmacokinetics and manual curation of top-scoring compounds identified six lead compounds that were compared in terms of protein-ligand contacts and protein-essential dynamics. The study shows that among the six candidates, Aurachin A and the Soraphinol analogues such as Soraphinol A and Soraphinol C remain very stable compared to other compounds, enabling the active site integrity via a stable dynamics pattern. We also show that other compounds such as Phenoxan, Phenylnannolone C, and 8E-Aurafuron B remain unstable and have a negative impact on the active site integrity and may not be suitable binders for TMPK protein. Analyzing the Aurachin A and Soraphinol A binding, the established hydrogen bonds with Arg93 and the conserved hydrophobic interaction with Tyr101 are consistent with previous experimental interactions. Additionally, a deeper insight into the indole and the aromatic ring interaction through π-π stacking and π-cation interactions, as well as the background of Aurachin A and Soraphinol A as a bioactive compound, has significant implications not only for its potential as a promising drug but also for directing future drug discovery efforts targeting the TMPK protein.

Computational assessment of marine natural products as LasR inhibitors for attenuating quorum sensing in Pseudomonas aeruginosa

The Quorum Sensing (QS) system in bacteria has become a focal point for researchers aiming to develop novel antimicrobials to combat multidrug-resistant bacteria. Pseudomonas aeruginosa, an opportunistic Gram-negative bacterium, has developed resistance against a variety of antimicrobial agents, making it a formidable pathogen responsible for nosocomial infections. QS system mainly controls the expression of genes responsible for biofilm formation and virulence of bacteria. Within the QS system of P. aeruginosa, the transcription activator LasR plays a pivotal role and is an appealing target for the development of antimicrobial agents. In this study, we employed molecular docking and molecular dynamics simulations to identify potential inhibitors of LasR by screening marine natural products (MNPs) from the CMNPD database. We identified ten MNPs with excellent docking scores (less than -11.7 kcal/mol) against LasR, surpassing the binding energy of the co-crystal 3-oxo-C12-HSL (-8.594 kcal/mol) and the reference compound cladodionen (-6.71 kcal/mol). Furthermore, we selected five of these MNPs with the highest MM/GBSA binding energies for extensive 100 ns molecular simulations to assess their stability. The molecular dynamics simulations indicated three MNPs, namely CMNPD10886, CMNPD20987, and CMNPD20960, maintained high stability throughout the 100 ns simulation period, as evidenced by their root mean square deviation, root mean square fluctuation, radius of gyration, and hydrogen bond interactions within the ligand-protein complex analysis. Furthermore, essential dynamics (PCA and DCCM) were performed to analyse the correlated motion of amino acids. These findings suggest that these compounds hold potential as inhibitors of LasR, offering promising prospects for the development of treatments against infections.Communicated by Ramaswamy H. Sarma.