Antiplasmodial Isoflavanes and Pterocarpans from Apoplanesia paniculata.

Bioassay-guided fractionation of an EtOH extract of the roots of the plant Apoplanesia paniculata (Fabaceae) led to the isolation of the three known compounds amorphaquinone ( 1 ), pendulone ( 2 ), and melilotocarpan C ( 3 ), and the two new pterocarpans 4 and 5 . Compounds 1 and 2 exhibited good antiplasmodial activity with IC 50 values of 5.7 ± 1.5 and 7.0 ± 0.8 µM, respectively. Compound 3 exhibited weak antiplasmodial activity (41.8 ± 5.2 µM), while compounds 4 and 5 were inactive. Compound 6 was synthesized to confirm the structure of 5 , and it showed enhanced antiplasmodial activity (15.8 ± 1.4 µM) compared to its analogues 3 – 5 .