Study on mechanism of total alkaloids of Sophora flavescens against Staphylococcus epidermidis / 中草药

ABSTRACT

Objective: To detect the effect of alkaloids of Sophora flavescens on biofilm formation in Staphylococcus epidermidis in vitro, and to observe whether total alkaloids of S. flavescens can affect the tolerance of Staphylococcus epidermidis to lactic acid and hydrogen peroxide, then explore the possible anti-microbial mechanism of alkaloids in Sophora flavescens. Methods: The biofilm of Staphylococcus epidermidis was prepared in vitro. We evaluated the effect of alkaloids in S. flavescens on the biofilm-forming ability of Staphylococcus epidermidis via 96-well cell culture microtiter plates with crystal violet staining as well as Congo red experiment. The biofilm formation of Staphylococcus aureus was observed using scanning electron microscope. Then, we measured the change of tolerance to oxidative stress and sensibility to antibiotics for Staphylococcus epidermidis being treated by alkaloids in S. flavescens Ait. qRT-PCR analysis was performed to show the relative transcript level of serp2195 and gpxA-2 upon Staphylococcus epidermidis strain exposed to alkaloids in S. flavescens at different concentrations. Results: Alkaloids in S. flavescens significantly prevented biofilm formation in Staphylococcus epidermidis (P < 0.001) at the concentration of 5.0 mg/mL during crystal violet staining and Congo red experiment, and thus weakened tolerance to oxidative stress and enhanced sensibility to lactate for Staphylococcus epidermidis. Alkaloids in S. flavescens could downregulate the transcript level of serp2195 and gpxA-2. Conclusion: Alkaloids in S. flavescens has a significant inhibitory effect on biofilm formation of Staphylococcus epidermidis, which weakens the tolerance of bacteria to oxidative stress. The mechanism may be realized by downregulating the transcript level of serp2195 and gpxA-2, and alkaloids in S. flavescens could reduce Staphylococcus epidermidis tolerance to lactic acid. To sum up, Alkaloids in S. flavescens can be applied to the gynecological infection caused by biofilm-producing bacteria.