Suadimins D-J, Monoterpenoid Indole-Quinoline and Bisindole Alkaloids from Melodinus suaveolens

Compounds 1-12, including seven complex monoterpenoid indole-quinoline and bisindole alkaloids, suadimins D-J (1-7) with previously unreported carbon-carbon linkages, were isolated and identified from the twigs and leaves of Melodinus suaveolens. Their structures were elucidated by a combination of diverse methods, especially the extensive spectroscopic data analysis and electric circular dichroism (ECD) calculations. The cytotoxicity of these compounds against three cancer cell lines was evaluated, some of which showed moderate activities with IC50 values ranging from 2.4 to 8.0 mu M.