Antioxidant Power and Antimicrobial Activity of Hydro-alcoholic Extract of Echinacea purpurea on Escherichia coli, Salmonella typhi, Staphylococcus aureus and Bacillus cereus

The increased resistance of bacteria to antibiotics has increased the tendency of consumers to use natural antimicrobial compounds. Purple Coneflower (Echinacea purpurea) contains bioactive compounds and it has long been used to treat many diseases. The aim of this study was to investigate the total content of phenolics and flavonoids, antioxidant activity, and antimicrobial property of hydro-alcoholic extract of Purple Coneflower on some pathogenic microorganisms.

In this study, the hydro-alcoholic extract (50% distilled water + 50% ethanol) was prepared according to the maceration method. Total content of phenolics and flavonoids, and antioxidant activity (DPPH and ABTS radical scavenging) were determined. The antimicrobial activity was evaluated through disk diffusion agar, well diffusion agar, minimum inhibitory concentration, and minimum bactericidal concentration, against Escherichia coli, Salmonella typhi, Staphylococcus aureus, and Bacillus cereus.

The minimum bactericidal concentrations for S. aureus, B. cereus, E. coli, and S. typhi were 16, 32, 64, and 64 mg/ml, respectively. In disk and well diffusion agar methods, the lowest and highest inhibition zones were observed for S. typhi and S. aureus, respectively. The hydro-alcoholic extract had a remarkable level of phenolic and flavonoid compounds and antioxidant activity.

The hydro-alcoholic extract of Purple Coneflower had a considerable antimicrobial effect against the bacterial species tested; however, the gram-positive bacteria were more sensitive to the extract in comparison to the gram-negative ones. Therefore, the Purple Coneflower could be used as an effective antimicrobial agent against pathogenic microorganisms.