Vasorelaxing alkaloids and flavonoids from Cassytha filiformis

Two new aporphine alkaloids, isofiliformine (1) and cassythic acid (3), along with 22 known compounds were isolated from whole herb of Cassytha filiformis. Cassythic acid (3), cassythine (4), neolitsine (7), and dicentrine (8) had potent vasorelaxing effects on precontracted rat aortic preparations with mean IC50 values between 0.08 and 2.48 mu M. Compounds 1, 1,2-methylenedioxy-3,10,11-trimethoxyapotphine (2), (-)-O-methylflavinatine (10), (-)-salutaridine (11), isohamnetin-3-O-beta-glucoside, and isohamnetin-3-O-rutinoside exerted moderate vessel-relaxing activities with IC50 values from 16.50 to 32.81 mu M at the test concentrations.