Isolation and antibacterial activity of three new flavonol compounds from <i>Sophora flavescens</i>

Three new flavonol compounds-kushenmin Q (<b>1</b>), kushenmin R (<b>2</b>), and kushenmin S (<b>3</b>)-along with two known compounds, 2<i>S</i>-sophoflavonoid B (<b>4</b>) and kushenol G (<b>5</b>), were isolated from the ethanol extract of <i>Sophora flavescens</i> root bark. Their structures were elucidated using UV spectroscopy, high-resolution electrospray ionisation mass spectrometry (HRESIMS), nuclear magnetic resonance (NMR), and comparison with published data. The antibacterial activity of compounds <b>1-5</b> was evaluated against eight bacterial strains (four Gram-positive and four Gram-negative) using the microbroth dilution method. Among the isolated compounds, the flavones <b>1</b>, <b>3</b>, and <b>4</b> exhibited significant antibacterial activity, with particularly strong effects against Gram-positive bacteria.