Antibiofilm, antiquorum sensing and antioxidant activities of Calendula officinalis L., Hypericum perforatum L. and Trachystemon orientalis (L.) G. Don essential oils

Bacteria can coordinate biofilm formation through antiquorum sensing and create a more effective defense mechanism. Therefore, strategies that inhibit biofilm formation and target the antiquorum sensing mechanism are needed to combat antibiotic resistance. This study was conducted to determine the antibiofilm and antiquorum sensing (anti-QS) effect of essential oils (EOs) obtained from Calendula officinalis L., Hypericum perforatum L. and Trachystemon orientalis (L.) G. Don. and also to calculate oxidative stress indices (OSI) by analysing oxidant and antioxidant capacity. Antibiofilm capacities of EOs against Escherichia coli were investigated by microplate method. Anti-QS activities were evaluated with the agar well diffusion test. The oxidant capacities of plant EOs, whose antioxidant value was determined with the Total Antioxidant Status kit (TAS), were also examined with the Total Oxidant Status kit (TOS), and the OSI were calculated from the ratio of the two. EOs of all three plants have strong antibiofilm and anti-QS effects. T. orientalis, which has 19 mm+ anti-QS effect, shows 93.11% biofilm inhibition effect and draws attention together with the other two plants used pharmacologically. EOs with low OSI levels are expected to have high phytotherapeutic efficacy. As expected, the EOs used are considered important components for their capacity to inhibit biofilm formation and the QS mechanism. This study constitutes the first step in using EOs as alternative agents for strategies that prevent the anti-QS mechanism and biofilm formation.