Experimental Investigations on the Antioxidant, Anti-Quorum Sensing, and Antibiofilm Activities of Ethanolic Extracts from Prunella vulgaris, Teucrium chamaedrys subsp. chamaedrys, and Thymus longicaulis subsp. longicaulis

Objective: The aim of this study was to evaluate the oxidant and antioxidant capacities, anti-quorum detection (QS) and antibiofilm activities of ethanol extracts obtained from Prunella vulgaris, Teucrium chamaedrys subsp. chamaedrys and Thymus longicaulis subsp. longicaulis. Materials and Methods: Antibiofilm activities were evaluated using the microplate method against a biofilm-forming Escherichia coli reporter strain. Anti-QS activities were evaluated qualitatively using the well diffusion method with Chromobacterium violaceum ATCC 12472 as a biosensor. Total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress index (OSI) were measured using commercial kits. Results: All three plant extracts showed strong biofilm inhibition. T. chamaedrys subsp. chamaedrys showed the highest antibiofilm activity with 94.07% inhibition at 12.5 µg/mL. In the anti-QS screening, T. longicaulis subsp. longicaulis extract showed the largest violacein inhibition zone (21.67±3.51 mm) at 75 mg/mL. This extract also exhibited the most favorable oxidative profile with the highest TAS and lowest OSI values among the tested samples. Conclusion: Ethanol extracts of the tested medicinal plants, especially T. longicaulis subsp. longicaulis, have significant antibiofilm, anti-QS and antioxidant activities. The findings indicate the potential of the extracts as natural agent sources to control the virulence properties of pathogens.