Benzophenanthridine alkaloids from the roots of <i>Thalictrum microgynum</i> Lecoy.ex Oliv

<p>A new benzophenanthridine alkaloid, 2,3,9-trimethoxy-7,8-methylenedioxy-5-methylbenzo[c]-6(5H) phenanthridone (<b>2</b>) and a benzophenanthridine alkaloid first found from natural sources, 2,3-dimethoxy-7,8- methylenedioxy-5-methylbenzo[c]-6(5H)- phenanthridone (<b>1</b>) together with two known benzophenanthridine alkaloids, Dihydrosanguinarine (<b>3</b>) and Dihydrochelilutine (<b>4</b>) were isolated from the roots of Thalictrum microgynum Lecoy.ex Oliv. The structures of <b>1</b> and <b>2</b> were elucidated using various spectroscopic techniques including HRESIMS and 1 D and 2 D NMR. Antibacterial activity of these compounds were tested. Compound <b>1</b>, <b>3</b> and <b>4</b> showed antibacterial activity against <i>Staphylococcus aureus</i> with MIC values of 50, 100, 25 μg/mL, respectively.</p>