Eremophilane sesquiterpenes from Ligularia macrophylla

Seven eremophilanes, including three previously undescribed compounds, were extracted and purified from whole plants of Ligularia macrophylla. Their structures, including absolute configurations, were characterized by spectroscopic, quantum chemical NMR, and Single-crystal X-ray methods. The antibacterial activity of these compounds was evaluated against Escherichia coli and Bacillus subtilis. Among them, compound 4 exhibited the most potent antibacterial activity against B. subtilis, with an inhibition zone of 30.58 ± 2.63 mm at 256 μg/mL. All compounds showed no activity against E. coli, as their minimum inhibitory concentration (MIC) exceeded 5 mg/mL.