Total phenolic content, antioxidant and antimicrobial activity of Equisetum arvense L.

The antioxidant and antimicrobial activity of Equisetum arvense L. harvested in a polluted urban area were investigated. The total phenolic content determined by a modified Folin-Ciocalteu method was 335.8 mg of GEA/g of the dried ethanol extract. Antioxidant activity determined by FRAP method was 28.7 mM Fe(II)/g of extract, whereas antioxidant activity index for stable DPPH free radicals was 3.86. The results were compared with control antioxidants (gallic acid, vitamin C, BHA and BHT). Antimicrobial activity was tested by monitoring the impact of different extract concentrations through measuring the change in optical density of bacterial suspension over time and by determining MIC and MBC using macrodilution method. E. arvense extract has been effective on the tested microorganisms depending on the concentration and exposure time. The extract had the strongest antibacterial activity on Staphylococcus aureus, with MIC and MBC of 11.14 mg/mL and 22.28 mg/mL respectively, and the weakest effect on Bacillus cereus, with MIC of 89.10 mg/mL.