In vitro antibacterial activity as related to antioxidant property of some ethnomedicinal plants

Abstract

The present study attempted to evaluate in vitro antibacterial and antioxidant activities of extracts from some ethnomedicinal herbs and to correlate among the parameters. The antibacterial activity was assayed using agar-disc diffusion method against seven bacterial species. Their total flavonoids content (TFC) and ferric reducing power (RP) were also evaluated. Herb extracts with high TFC exhibited a good antibacterial activity against the bacteria at low concentrations. The Gram-positive bacteria were more sensitive to the tested extracts than the Gram-negative ones. While Staphylococcus aureus was maximally inhibited, Escherichia coli was most resistant. Against each bacterium, antibacterial activity was positively correlated (r = 0.60-0.87) with TFC of the tested extracts. Positive correlations were also obtained between antibacterial and antioxidant activities (r = 0.60-0.96) as well as between TFC and antioxidant activity (r = 0.91) of the extracts. Thus, antibacterial and antioxidant activities of the tested extracts were closely associated with their flavonoid constituents.