Hispanic Medicinal Plants for Managing Chronic and Infectious Diseases
MetadataShow full metadata
Pseudomonas aeruginosa (PAO1), an opportunistic pathogen in immune compromised patients is under the regulation of the LasR-RhlR system for its QS mediated development of virulence. Medicinal plants used Hispanic medicine used for several centuries to treat common ailments, are well known for their antimicrobial effects on a variety of human pathogens. However, few studies have investigated its QS related antivirulent activities. Our objective was to screen for the QS inhibitory properties of 20 high quality Hispanic/South American medicinal plants, understand their mechanism of action and investigate their effect on the expression of QS regulated virulence factors in PAO1. Methods: QS inhibition (QSI) of sub-lethal concentrations (SLC) of plant extracts was measured in violacein producing Chromobacterium violaceum (O26, 31532) bioassay model. Effect of these extracts on PAO1 virulent factors pyocyanin, elastase, and total protease were quantified by standard protocols. Results indicated that all GT extracts reduced violacein production by 56 75%. The results suggested the primary mechanism of QSI was a combination of (1) reduction in AI formation and (2) inhibition of AI activity. The extracts reduced pyocyanin synthesis, with 7 extracts completely inhibiting its formation and secretion. The 7 extracts also completely inhibited the expression of elastase. The specific activity of total proteases secreted by PA-O1 was lower than the control for all the extracts that had quorum sensing inhibition activity. We observed that the extracts from these plants inhibit QS related virulent processes in PA-O1 primarily by inhibiting synthesis of AI and by interfering with their activity.