Larvicidal and Antibiofilm Potential of Three Mountain Plants: Centaurea ensiformis, Origanum hypericifolium, Paeonia turcica

Abstract Plants are known to produce a diverse group of natural metabolites with different biological activities. Centaurea ensiformis P.H. Davis, Origanum hypericifolium O. Schwartz & P.H. Davis and Paeonia turcica Davis & Cullen are endemic plant species that grow on mountains in select regions in Türkiye and have been used in traditional Turkish medicine for various ailments. As a first, we evaluated the larvicidal and antibiofilm activities of ethanol, ethyl acetate, acetone and water extracts obtained from these plants. Antioxidant activities of the extracts were also investigated. All tested extracts were effective at concentrations > 25ppm on Aedes aegypti larval mortality with the LC₅₀ values ranging between of 32.82–48.35 ppm and LC₉₀ between 46.26–63.2 ppm. O. hypericifolium was the most effective plant, ethanol extracts presented LC₅₀ values of 32.82 ppm. Extracts demonstrated varying degrees of antibiofilm activity depending on the dose and bacterial species. Origanum hypericifolium extracts notably inhibited biofilms of Staphylococcus aureus (up to 98% inhibition), while P. turcica showed moderate efficacy against the same bacterial species. Pseudomonas aeruginosa biofilms displayed high resistance to all extracts. The results indicate that these endemic Turkish plants possess promising larvicidal and antibiofilm potential, particularly Origanum hypericifolium. Further research should elucidate the bioactive compounds responsible for these activities, optimize extraction methods, and explore potential applications in mosquito control and biofilm-related infections.