HPLC quantification of fourteen flavonoids in <i>Sophora flavescens</i> Aiton extracts and component-effect relationship against <i>Acinetobacter baumannii</i>

<i>Sophora flavescens</i> Aiton is a traditional Chinese medicine for clearing heat and dampness. 80% ethanol extracts from 13 batches of this herb displayed 2.42%-82.88% inhibition at 512 μg/mL against <i>Acinetobacter baumannii</i>, a bacterium that cause a variety of healthcare-associated infections. In this study, a new HPLC-DAD method was developed for simultaneous quantification of 14 flavonoids, and an orthogonal signal correction assisted partial least squares regression chemometric method was firstly applied to analyse component-effect relationship of extracts against <i>A. baumannii</i>. Five major flavonoids, viz. trifolirhizin (<b>20</b>) (0.81%-3.37%), sophoraflavanone G (<b>4</b>) (0.77%-6.01%), kushenol N (<b>22</b>) (0.23%-2.31%), kurarinone (<b>9</b>) (1.84%-7.29%) and isoxanthohumol (<b>12</b>) (0.06%-1.41%), with variable importance projection values exceeding 1, were found to play important roles. Among them, <b>9</b> and <b>22</b> were negatively correlated with extract's antibacterial activity, whereas <b>4</b>, <b>12</b> and <b>20</b> were positively correlated. These flavonoids may be regarded as biomarkers of <i>S. flavescens</i> extracts against <i>A. baumannii</i>.