The research of the plant-derived molecules regulatory effects regarding the bacterial biosensors with the different “quorum sensing” systems of the LuxI/LuxR type

Relevance. «Quorum sensing» (QS) plays an important role in the pathogenic potential realization of many malignant bacteria, and therefore is a promising direction for the in-depth study. It could provide the basis for the antibacterial agents creation of new operating principles. The use of plant extracts and small molecules identified in them is the one option to inhibit «quorum sensing» system, but this approach has certain limitations. In addition, the use of a limited number of bacterial biosensors leaves questions related to extrapolate data on the whole system and needs more research.

Aim. Comparison of the QS-inhibitory activity of plant-derived molecules against the «quorum sensing» LuxI/LuxR-type system of the violacein-producing strain Chromobacterium subtsugae 026, as well as a panel of bacterial lux-biosensors.

Material and methods. The work used a library of chemically synthesized analogues of plant-derived molecules, represented by quercetin, cinnamic aldehyde, 7-hydroxycoumarin, 4-hexylresorcinol and salicylic acid. The influence on the growing and the QS-inhibitory activity of the plant-derived molecules were evaluated using the serial dilution method. The QS-inhibitory effect of the studied compounds was determined according to the optical density measurement of the Chromobacterium subtsugae 026 strain extracted pigment and the measurement of bacterial lux-biosensors bioluminescence.

Results. A panel of seven bacterial biosensors was used to screen the biological activity of quercetin, cinnamic aldehyde, 7-hyd-roxycoumarin, 4-hexylresorcinol and salicylic acid against four «quorum sensing» LuxI/LuxR-type systems. The unequal nature of the action of the studied compounds on the tested «quorum sensing» systems was demonstrated. It was found that the 4-hexylresorcinol QS-inhibitory action was most pronounced regarding Chromobacterium subtsugae 026, while the trans-cinnamaldehyde was more active regarding bacterial lux-biosensors.

Conclusions. The presented work demonstrates the unequal nature of the action of the plant-derived molecules under study in relation to four different QS LuxI/LuxR-type systems. It has been suggested that this circumstance may be associated with a different mechanism of action of the studied substances on the bacterial cell. The results are of practical interest and require further study.