Antioxidant and Antimicrobial Activities of Cynara scolymus L. Rhizomes

The natural forests and meadows of the Green Mountain of Libya are classified as the richest floristic region of the country. Among various species Cynara scolymus L. (Asteraceae), is the most used medicinal plant. C. scolymus L., has long been regarded as noncrop food and also as an effective medicinal plant. In the current study, total phenols as well as flavanoids were determined in methanolic and aqueous extracts the of C. scolymus L. rhizomes in order to assess their contribution to the antioxidant activity. Free radical scavenging activity of the extracts was investigated and compared with ascorbic acid. Methanolic extract exhibited a higher total phenols (45.11 mg GAE/g DW) and flavonoids (37.00 mg Rutin/g), that results in a high antioxidant activity with IC50 (17.77 µg/ml). In contrast, aqueous extract showed a lower total phenolic and flavonoid contents (37.79 mg GAE/g DW and 15.51 mg Rutin/g DW, respectively) and IC50 (66.3 µg/ml). Isolated flavonoids showed the highest free radical scavenging activities (IC50 = 13.33 µg/ml). The in vitro antibacterial activity of C. scolymus L. rhizomes was investigated against various strains of bacteria by hole-plate diffusion method. The minimum inhibitory concentrations (MICs) of the crude methanol, flavonoids and alkaloids extracts found to be between 0.03 and 200 mg/ml for the susceptible organisms, with that of MRSA being the least.