Determination of phytocompounds and their role in inhibition of efflux pump-related resistance in Pseudomonas aeruginosa PA7.

Antimicrobial Resistance (AMR) remains a global health threat, with efflux pump-based mechanisms being a significant contributor to bacterial drug resistance, highlighting the importance of exploring alternative strategies such as plant-based phytochemicals. Pseudomonas aeruginosa is a pathogen that heavily depends on its Resistance-Nodulation-Division (RND) efflux systems, like MexAB-OprM, as its resistance pathway against antibiotics. By inhibiting these efflux pumps, the pathogen can potentially be susceptible to the same antibiotics it was resistant to. Phytochemicals derived from medicinal plants offer a large scale of bioactive compounds with potential efflux inhibitory properties. However, the inhibitory effects and activity of bioactive compounds from Brassica nigra and Foeniculum vulgare remain largely unexplored, especially with P. aeruginosa. In this study, the crude extracts from mustard and fennel were evaluated for their ability to affect the efflux resistance in P. aeruginosa PA7 (MTCC 1688). Mustard extract demonstrated a stronger inhibitory effect and increased antibiotic susceptibility compared to Fennel extract, which was supported by intracellular accumulation and bacterial growth behaviour. GC-MS profiling helped identify key components of the extract, and molecular docking revealed that mustard-based compounds showed a higher affinity towards the MexB protein. Molecular dynamics simulations further confirmed the stability of compounds from mustard and MexB interactions as potential ligands. Overall, the findings suggest that the mustard phytochemicals may be a promising natural efflux pump inhibitor capable of increasing the potency of antibiotic activity against P.aeruginosa, increasing their relevance in combating AMR.