Abstract

The different organic solvent extracts of roots of Dryneria quercifolia J. Smith were tested for their antibacterial activity and cytotoxicity. Chloroform and ethyl acetate extracts (150mg/disc) showed good antibacterial activity as determined by disc-diffusion method against four Gram-positive and six Gram-negative bacteria than petroleum ether extract. The minimum inhibitory concentration (MIC) of each extract was determined by serial dilution technique against Escherichia coli, Shigella dysenteriae, Salmonella typhi, Bacillus subtilisand Streptococcus-b-haemolyticus. The MIC values ranged from 16 to 64 mg/ml. The cytotoxicity of each extract was assessed by brine shrimp lethality bioassay and LC₅₀values were determined. The LC₅₀ values for petroleum, chloroform and ethyl acetate extracts were 22.0, 16.5 and 16.5 mg/ml, respectively. The positive results of these bioactive extracts should encourage the further investigation of the active principles responsible for these activities.

Key words: Dryneria quercifolia, antibacterial activity, minimum inhibitory concentration, cytotoxicity.