Aromatherapeutic essential oils and their pharmaceutical combinations: Tools for inhibition of quorum sensing activity and biofilm formation of human pathogens

Background and Aims: Aromatherapy, as one of the complementary therapies, uses essential oils as the main therapeutic agents to treat several diseases. In the present study, it was aimed to investigate inhibition of quorum sensing (QS) and biofilm formation of aromatherapeutic essential oils (AEOs) and their pharmaceutical combinations (PC-I and PC-II). Methods: The anti-QS potential of AEOs were determined using the biosensor strains Chromobacterium violaceum ATCC 12472 and Pseudomonas aeruginosa PA01. Anti-QS activity was detected by agar-well diffusion and violacein pigment inhibition assays. Blocking of PA01 swim and swarm motilities and biofilm formation was also performed. Results: Most of the AEOs demonstrated highly active (>95%) violacein pigment inhibition. Additionally, they inhibited swarming (40.34%-72.80%) and swimming (20.06%-50.08%) motilities of PA01. Moreover, the majority of AEOs also decreased the biofilm formation, particularly on P. aeruginosa and S. aureus. Conclusion: Consequently, aromatherapeutic formulations might be a complementary or prophylactic cure for infectious disease by their anti-OS and antibiofilm activities rather than just antimicrobial effects.