Inhibition of Quorum Sensing System in Pseudomonas aeruginosa by Psammaplin A and Bisaprasin Isolated from the Marine Sponge Aplysinella rhax
Natural products isolated from marine sponges have exhibited profound bioactivity and, in some cases, serve as potent quorum sensing inhibitory agents by preventing microbial biofilm formation. In this study, the inhibitory potential of the psammaplin type compounds, psammaplin A (1) and bisaprasin (2), isolated from the marine sponge, Aplysinella rhax, was evaluated in the quorum-sensing inhibitory assay based on the Pseudomonas aeruginosa PAO1 lasB-gfp and P. aeruginosa PAO1 rhlA-gfp biosensor strains. The result indicated that psammaplin A (1) showed moderate inhibition against lasB-gfp biosensor strains but significantly inhibited the QS-gene promoters, rhlA-gfp with IC50 value at 30.69 and 2.64 M, respectively. In contrast, bisaprasin (2) displayed significant inhibition for both biosensor strains, lasB-gfp and rhlA-gfp with IC50 values at 8.70 and 8.53 M, respectively. To our knowledge, the antiquorum sensing activity of these marine-derived bromotyrosine compounds is described here for the first time. Significance and Impact of the StudyThe attention of the scientific community has been drawn to using marine sources to find novel quorum sensing inhibitors as antipathogenic drugs to combat antimicrobial resistance and pathogenesis caused by the proliferation of pathogenic bacteria mediated by the quorum sensing (QS) system. By blocking the QS signalling communication, the ability to assemble an organised community structure that enables drug resistance and production of virulence factors will be attenuated. The significance of this investigation is based on the discovery of bromotyrosine derivatives as potential new drug leads for the development of antipathogenic agents.