Antioxidant and Antimicrobial Activities of Ethanol Extracts of Cynara Scolymus (Cynarae folium, Asteraceae Family)

Purpose: Cynara scolymus is a medicinal plant frequently used in traditional medicine for stomach and liver diseases. The purpose of the study was to identify the most suitable extraction solvent for maximum antioxidant and antimicrobial effect of fluidized bed extracts. Methods: The extracts were obtained by conventional maceration and fluidized bed extraction using 25, 50, 75 and 97 % v/v ethanol as solvent. The antioxidant effect of the extracts was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. The quantities of phenols and flavonoids, and the reducing power of the extracts were also determined. The antimicrobial activity of the extracts was tested against different microbial strains using agar well diffusion method. The minimum inhibiting concentration (MIC) of the fluidized bed extract was also determined. Results: The ethanol extract showed the highest antioxidant activity as well as yielded the largest quantity of polyphenolic compounds. For the extract obtained by fluidized bed technique, the optimum concentration of 10 mg/ml gave maximum antioxidant activity of 65.15 %. The MIC values obtained using the freeze-dried extract ranged from 5.0 mg/ml - 15.0 mg/ml. The extracts showed significant inhibitory activity against the tested strains of Listeria innocua CMGB 218, Bacillus cereus CMGB 215 with MIC of 5 mg/ml but showed MIC of 15 mg/ml for the other strains. Conclusion: The results indicate that the freeze-dried extract from Cynara scolymus is capable of yielding nutritional supplements with antioxidant and antimicrobial activities.