Flavonoids extract from <i>Portulaca oleracea</i> L. induce <i>Staphylococcus aureus</i> death by apoptosis-like pathway

Abstract

Portulaca oleracea L. (P. oleracea) has been used as a Chinese herbal medicine for the treatment of antipyretic, anti-scorbutic, antiseptic, antispasmodic, diuretic, anthelmintic, and urinary disorders. However, pharmacological studies are necessary to provide a scientific basis to substantiate its effectiveness. In this study, the antimicrobial effect and its mechanism of the flavonoids extract from P. oleracea. (POFE) were investigated. The antibacterial effects of POFE were tested on Enterobacter cloacae, Klebsiella pneumonia, Escherichia coli, Staphylococcus aureus, Salmonella enterica and Micrococcus luteus, and the results showed that some bacteria, especially Staphylococcus aureus, were sensitive to POFE. At the tested concentrations, POFE-treated cells displayed various apoptotic markers, such as reactive oxygen species (ROS) accumulation, membrane depolarisation, phosphatidylserine (PS) exposure, DNA fragmentation, and caspase-like protein, in a dose-dependently manner. Based on these data, we concluded that POFE entered the cytoplasm through the membrane pores of Staphylococcus aureus, and subsequently, two parallel reactions took place, namely increase in the level of ROS and DNA fragmentation, which caused cell death.