Cymoside, a monoterpene indole alkaloid with a hexacyclic fused skeleton from Chimarrhis cymosa

Abstract Cymoside, an oxidized derivative of strictosidine with an unprecedented hexacyclic skeleton which includes a double bridge linking the indole and the monoterpene moieties has been isolated from the leaves of Chimarrhis cymosa . The structure of this alkaloid, its relative and absolute configurations have been established by spectroscopic data including 1D and 2D NMR experiments (COSY, HSQC, HMBC, NOESY), HRESIMS and electronic circular dichroism (ECD) calculations.