Antibacterial, antioxidant and cytotoxic activities of extracts of Conyza canadensis (L.) Cronquist growing in Tunisia

Antibacterial antioxidant and cytotoxic activities of petroleum ether, ethyl acetate and methanol extracts of Conyza Canadensis (L.) Cronquist were investigated. Antibacterial activity was evaluated using the agar diffusion and microwell dilution assays against four strains of bacteria. Antioxidant activity was measured by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method and the cytotoxic activity was tested against Hep-2 cells (laryngeal carcinoma cell line) using methylene blue assays. Among tested extracts, the methanolic extract exhibited important antibacterial activity. It also showed good antioxidant activity with 50% inhibition concentration (IC₅₀) of 120 μg/ml. Cytotoxicity of extracts was time depend, increasing with exposure time and concentration. At 72 h of incubation, the ethyl acetate and petroleum ether extracts demonstrated effective cytotoxic activity against Hep-2 cells with IC₅₀ values of 45 and 50 μg/ml, respectively.