Rare bisindole alkaloids from the Amazonian tree Raputia simulans.

The stem bark of Raputia simulans (Rutaceae) has been reported to contain simple and dimeric indole alkaloids. Further phytochemical investigation of R. simulans stem bark resulted in the isolation of three new alkaloids. These compounds represent a relatively new category of dimeric indole alkaloids with a cyclohexene moiety in their core. Their structure elucidations were based on NMR and HR-MS techniques, while structural aspects concerning their relative configuration were investigated using molecular mechanics calculations and NOESY experiments.