Antimicrobial metabolites from Saraca asoca impairs the membrane transport system and quorum-sensing system in Pseudomonas aeruginosa.

This study was conducted to explore the antimicrobial mechanism of metabolites from Saraca asoca (SA1) using differential proteomics and metabolic profile of Pseudomonas aeruginosa after treatment with effective sub-MIC dose of 312 µg/mL. SA1 fraction was found to contain antibacterial metabolites catechol, protocatechuic acid, and epigallocatechin gallate. Proteome analysis revealed 33 differentially expressed proteins after SA1 treatment. Protein network analysis showed that SA1 treatment upregulated the DNA topological and metabolic processes. Furthermore, it revealed that T2SS, cellular component biogenesis, and response to chemical stimuli were inhibited by SA1 treatment, supported by down-regulated Na/H antiporter, SdeX, ompK, and trbD proteins. Statistical analysis of mass data revealed the altered level of 20 metabolites includes HSLs, PQS, rhamnolipid, and pyocyanin. Proteome and metabolome results showed that treatment impaired cell membrane functions and quorum-sensing system. It was further confirmed by increased MDA (3.95 fold), and rhamnolipids (4.3 fold) production and, therefore, oxidative stress (36.9%) after SA1 treatment.