Four new flavonoids from Sophora flavescens and their antibacterial activities

Three new flavanones sophoflavanone C (1), sophoflavanone D (2), sophoflavanone E (3), and one new flavanonol, sophoflavanone F (4), were isolated from the ethanol extract of the root bark of Sophora flavescens. The structures of these compounds were identified by UV spectroscopy, high-resolution electrospray ionisation mass spectrometry (HRESIMS), nuclear magnetic resonance spectroscopy (NMR), and comparison with previous reports. Additionally, the antibacterial activity of compounds 1–4 against eight bacterial strains, including four Gram-positive bacterial strains and four Gram-negative bacterial strains, was determined using the micro broth dilution method. Both isopentenyl flavones, sophoflavanone C (1) and sophoflavanone F (4) exhibited significant antibacterial activity against the Gram-positive bacterial strains.