Biological activities and determination of the mode of action of Tunisian Globularia alypum and Cistus monspeliensis ethanolic extracts.

This study was designed to evaluate the antioxidant and antimicrobial activity of ethanolic extracts (EEs) of Cistus monspeliensis and Globularia alypum . C. monspeliensis showed the highest values of phenolic compounds. Further, it was shown that EE of C. monspeliensis displayed the highest DPPH (IC50 = 8.3 ± 1.08 mg/mL). The chemical profiles demonstrated a total of 12 and 13 phenolic compounds for C. monspeliensis and G. alypum , respectively. EEs of both plants possessed broad-spectrum antimicrobial activity when tested against Escherichia coli and Staphylococcus aureus . Treatment of studied strains with these extracts at their MICs reduced considerably the bacterial viability. The extracts did not induce total bacterial lysis, as determined by the measurement of optical density at 620 nm. Strains treated with EEs at Minimum Inhibitory Concentrations showed significant loss of tolerance to NaCl. Our results contribute to understanding the antibacterial mechanism of ethanolic extracts of the studied medicinal plants.