The Inhibition Of Scutellaria Baicalensis Extract On Listeria Monocytogenes Infection

Listeria monocytogenes(L.monocytogenes),is the most infectious pathogen of the six kinds of common Listeria monocytogenes.It is a facultative anaerobic opportunistic pathogen with strong athletic ability,and it is the main pathogen of Listeria monocytogenes infections.Listeria monocytogenes are widespread in the natural environment,common in human and animal faeces,soil,aquatic environments,and foods from various plant and animal sources(such as milk,eggs,sausages,vegetables and so on).It always opportunistically causes infections to the elderly,pregnant women,children and other people with low immunity.With the abuse and misuse of antibiotics,bacterial resistance has gradually become an important problem in the treatment of clinical infection diseases.Listeria monocytogenes,is also regarded as an important threat to human and animal health.In recent years,with the development of anti-virulence strategies,more and more attention has been paid to the role of bacterial virulence factor in the process of invasion.Like other Gram-positive bacteria,Listeria monocytogenes express a variety of virulence factors for the survival and proliferation.When the bacteria are phagocytosed by the host cell and then trapped in the cell's phagocytic bubble,a large amount of listeriolysin O(LLO)will be expressed by Listeria monocytogenes,which are used to help the bacteria escape to the cytoplasm and complete the proliferation process.Studies have shown that when the LLO coding gene of Listeria monocytogenes were knocked,the bacteria finally lost the ability in escaping from the phagocytic vesicles and the pathogenic ability to model animals.Therefore,LLO is a potential therapeutic target for Listeria monocytogenes infections.In this study,hemolysis experiments,growth curve and Western blotting experiments showed that the extract of Scutellaria baicalensis could significantly inhibit the hemolysis activity of culture supernatant in a low concentration range(8-64 ug/ml),but the concentration range did not affect the growth of bacteria,nor the expression of bacterial porogenous toxin LLO,but directly neutralized LLO mediated pore forming activity.In vitro cell infection test,the treatment of Scutellaria baicalensis extract reduced the proliferation of bacteria in cells,and the cytotoxicity mediated by bacteria also decreased significantly.In vivo animal infection test showed that Scutellaria baicalensis extract could reduce bacterial colonization in target tissues and inhibit animal death caused by bacterial infection.Scutellaria baicalensis is one of the most commonly used drugs in traditional Chinese medicine with various of biological activities such as anti-tumor,anti-bacteria,anti-inflammatory and free radical scavenging.This study provides an important experimental basis for the mechanism of extract of Scutellaria baicalensis inhibiting LLO hemolytic activity,and provides an important theoretical basis for the treatment of Listeria monocytogenes infection.