Benzophenanthridine alkaloids from the roots of Thalictrum microgynum Lecoy.ex Oliv.

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