Beyond antibiotics: Essential oils as novel biofilm inhibitors

Background: Multidrug and extensively antibiotic-resistant microorganisms, also known as “superbugs,” are now becoming a global threat to mankind. Bacteria constitute a protective layer of extracellular polymeric substances (EPS) around their colonies, which produces persistent bacterial infection. Bacteria coordinate in aggregated biofilm with each other through a mechanism named quorum sensing. Objective: This study aimed to explore the potential of essential oils as novel agents for inhibiting bacterial biofilm formation, specifically through their quorum sensing inhibitory properties. Methods: The extracts and essential oils of three herbal plants, viz. lavender oil, peppermint oil and clove oil, were used for different biological, therapeutic, anti-quorum sensing and biofilm inhibition. Chemical fingerprints of essential oils and extracts were performed using GC-MS and HPLC. Hemolytic activity and Ames assay was performed to document toxicological profile of samples. Anti-quorum activity of essential oils and extracted bio-functional components was performed against sinusitis isolates and reporter strain. Results: According to toxicological analysis, samples were non-toxic. Ames assay expressed that the samples used were non mutagenic while, DNA damage protection assay exhibited that essential oils and water extracts protected the DNA damage. High antibacterial activity of lavender essential oil was 21.83 ± 1.60 mm. According to SEM studies, essential oils and extracts have shown the destruction in three-dimensional structure of biofilm matrix with shrinkage of bacterial cell. The potency of extracts on violacein production is studied and results bring about moderate to good inhibition. Conclusion: It is concluded that due to antibiotic resistance, medicinal plant extracts are an alternative for chronic infection treatment.