The Effect Of Scutellaria Baicalensis Georgi Exact On Staphylococcus Aureus α-hemolysin

Staphylococcus aureus (S. aureus) is a widely distributed opportunistic pathogenthat may cuase various fatal infections in human and animals, such as pneumonia,endocarditis and skin and soft tissue infection. Since1960s, the first use of antibioticsin the clinic, the emergence and development of resistance renders S. aureus a worldchallenge, especially with the emergence of Vancomycin-resistant S. aureus. There islitmited choice for the infections caused by these resistance strain, which has quicklybecame the public safety and health problem in the worldTo deal with resistance strain-mediated infections, new antibiotics based on thestructure of available antibiotics or the same target was developed, which was easy toinduce drug resistance of pathogens. Therefore, developing other anti-infectivestrategies is another road for the infections caused by pathogens, especially resistancestrains. Among these strategies, anti-virulence is attracting more and more attentions.Compared with traditional antibiotics, anti-virulence strategy is thought as putting lesssurvival selective pressure and uneasy to induce drug resistance.Our country is full of traditional medicine, which has low mammalian toxicity,low residue and uneasy to induce drug resistance propertiy. Many traditionalmedicines without anti-bacterial activity can inhibit the infections caused by thesepathogens, which has not been still clear exclude the opsonization on the host.Therefore, screening anti-virulence drug in traditional medicine is not onlysupplementary for the medical development but also for the mechanism used bytraditional medicine against pathogens-mediated infections.In the present study, we found that the MICs of Scutellaria baicalensis Georgiexact against the tested S. aureus strains were≥1024μg/mL. Furthermore, thiscompound has no effects on the growth of S. aureus strains ATCC29213and8325-4with the concentrations of16-128μg/mL. However, with these concentrations of Scutellaria baicalensis Georgi exact, the hemolytic activities in the supernant weresignificantly reduced. But the content of α-hemolysin was not reduced by thiscompound. Additionally, the transcriptional level of hla (enconding α-hemolysin) andagrA (upregulating the transcriptiona of α-hemolysin) was also not affected aftertreated with this compound. These results indicted that this compound may directlyattenuate α-hemolysin-mediated hemolysis. As expected, the hemolytic activityinduced by purified α-hemolysin was significantly inhibited with a dose-dependentmanner when the reaction was treated with various concentrations of Scutellariabaicalensis Georgi exact. Furthermore, this compound also alleviated A549cell injurycaused by S. aureus.The above experimental results indicted that the Scutellaria baicalensis Georgiexact can directly inhibit α-hemolysin-mediated hemolysis and alleviated A549cellinjury caused by S. aureus, which states this compound can be used for the infectionscaused by S. aureus, especially S. aureus pneumonia.