Determination of effects on anti-microbial activity and quorum sensing mechanisms of extracts driven from some plants growing in Ri̇ze

In recent years the rapidly increasing antimicrobial resistance causes the existing antibiotics to become insufficient. Therefore, the search for new antimicrobial active substances increases the interest in natural products and herbal medicines. Especially nowadays, it is observed that the interest in the use of natural products for medical purposes increased rather than chemical. Plants have been used in medicine for centuries to treat infections and continue to play an important role in the discovery of new compounds today. In our study, various extracts of 44 plant species belonging to Rize province were prepared by maceration method. Antimicrobial activities of the plants were tested on 11 bacteria one of which was mycobacterium, and two fungal species by agar-well diffusion method. From quorum sensing mechanisms; violacein pigment inhibition was tested in four Chromobacterium violaceum strains, pyocyanin pigment inhibition was tested in Pseudomonas aeruginosa PAO1 strain. Biofilm growth and swarming suppression properties of the extracts with high antimicrobial activity were investigated with P. aeruginosa PAO1 strain. When the results were evaluated, it was determined that especially Castanea sativa Mill., Quercus sp., Geranium sp., Alchemilla oriturcica, Helichrysum armenium, Starchy sp. had effective antimicrobial activity against the tested microorganisms. Extracts of Castanea sativa Mill among these plants were found to show strong anti-quorum sensing activity by inhibiting violasin pigment in all C. violaceum strains at the same time preventing swarming and biofilm development. Six of the plants with high antimicrobial activity had anti-quorum sensing activity, while two of the plants had biofilm and swarming inhibition properties. The results of this study show that the aforementioned herbs may be good candidates for the development of new antimicrobial and anti-quorum sensing agents.