A new C-C linked benzophenathridine-2-quinoline dimer, and the antiplasmodial activity of alkaloids from .

The CHCl/MeOH (1:1) extract of stem bark showed good antiplasmodial activity (IC 2.5 ± 0.3 and 2.6 ± 0.3 µg/mL against the W2 and D6 strains of respectively). From the extract five benzophenanthridine alkaloids [8-acetonyldihydrochelerythrine (), nitidine (), dihydrochelerythine (), norchelerythrine (), arnottianamide ()]; a 2-quinolone alkaloid [-methylflindersine ()]; a lignan [4,4'-dihydroxy-3,3'-dimethoxylignan-9,9'-diyl diacetate ()] and a dimer of a benzophenanthridine and 2-quinoline [holstzianoquinoline ()] were isolated. The CHCl/MeOH (1:1) extract of the root bark afforded , -, , chelerythridimerine () and 9-demethyloxychelerythrine (). Holstzianoquinoline () is new, and is the second dimer linked by a C-C bond of a benzophenanthridine and a 2-quinoline reported thus far. The compounds were identified based on spectroscopic evidence. Amongst five compounds () tested against two strains of , nitidine (IC 0.11 ± 0.01 µg/mL against W2 and D6 strains and norchelerythrine (IC value of 0.15 ± 0.01 µg/mL against D6 strain) were the most active.