Three Chalconoids and a Pterocarpene from the Roots of Tephrosia aequilata.

In our search for new antiplasmodial agents, the CH₂Cl₂/CH₃OH (1:1) extract of the roots of was investigated, and observed to cause 100% mortality of the chloroquine-sensitive (3D7) strain of at a 10 mg/mL concentration. From this extract three new chalconoids, -2',6'-dimethoxy-3',4'-(2'',2''-dimethyl)pyranoretrochalcone (, aequichalcone A), -2',6'-dimethoxy-3',4'-(2'',2''-dimethyl)pyranoretrochalcone (, aequichalcone B), 4''-ethoxy-3''-hydroxypraecansone B (, aequichalcone C) and a new pterocarpene, 3,4:8,9-dimethylenedioxy-6a,11a-pterocarpene (), along with seven known compounds were isolated. The purified compounds were characterized by NMR spectroscopic and mass spectrometric analyses. Compound slowly converts into in solution, and thus the latter may have been enriched, or formed, during the extraction and separation process. The isomeric compounds and were both observed in the crude extract. Some of the isolated constituents showed good to moderate antiplasmodial activity against the chloroquine-sensitive (3D7) strain of .