Isolation of new rotenoids from Boerhaavia diffusa and evaluation of their effect on intestinal motility

A bioassay-guided separation of a methanolic extract obtained from the roots of Boerhaavia diffusa L. (Nyctaginaceae) allowed us to isolate five compounds belonging to the class of rotenoids: the known boeravinone D ( 1), boeravinone E ( 2), compound 5 and two novel compounds that we have named boeravinone G ( 3) and boeravinone H ( 4). The structures of the new molecules have been determined on the basis of their HR-EI-MS, (1)H- and (13)C-NMR and 2D-NMR (HMQC, HMBC) data. All the isolated rotenoids have been evaluated for their effect on intestinal motility in vitro. Three of them (boeravinone G, boeravinone E and compound 5) exhibited spasmolytic activity. Preliminary structure-activity relationships have been established highlighting the effect of substitutions on rings B and D.