Strychnohexamine from Strychnos icaja; the first naturally occurring indolomonoterpenoid trimeric alkaloid

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A Concise and Versatile Double-Cyclization Strategy for the Highly Stereoselective Synthesis and Arylative Dimerization of Aspidosperma Alkaloids

Building cycles: A strategy for the concise, stereoselective synthesis of aspidosperma alkaloids and related structures via a common putative diiminium ion intermediate is reported. The approach enables the dimerization of aspidosperma-type structures at the sterically hindered C2 position. The intermediate is prepared in one step from the shown lactam through an electrophilic double-cyclization cascade (see scheme; Tf=trifluoromethanesulfonyl).National Institute of General Medical Sciences (U.S.) (GM074825

Chrysopentamine, an antiplasmodial anhydronium base from Strychnos usambarensis leaves

A new derivative of strychnopentamine was isolated from the leaves of Strychnos usambarensis. This compound, named chrysopentamine, was identified by detailed spectroscopic methods (UV, IR, HR-ESI-MS, 1D and 2D NMR). Chrysopentamine presented an original hydroxy substitution on C-14 and an aromatization of the ring D of strychnopentamine leading to anhydronium base proper-ties and exhibited strong antiplasmodial properties (IC50 less than 1 muM)

Isolation of indole alkaloids from Catharanthus roseus by centrifugal partition chromatography in the pH-zone refining mode

International audienceCentrifugal partition chromatography (CPC) in the pH-zone refining mode allowed a preparative and efficient isolation of vindoline, vindolinine, catharanthine and vincaleukoblastine from a crude mixture of Catharanthus roseus alkaloids. The separation protocol was tested with a synthetic mixture of vindoline, catharanthine and vincaleukoblastine. The fraction content was analyzed and the results compared with theoretical chromatograms obtained by numerical simulation. The increase in injected sample mass results in an improvement of the purity of the isolated compounds. This observation, confirmed by theory, is of prime importance for the development of preparative pH-zone refining CPC as a preparative separation method

Moandaensine, a dimeric indole alkaloid from Strychnos moandaensis (Loganiaceae)

Moandaensine contains a rare anhydronium base subunit. It presents a moderate antiplasmodial activity with IC values of 11.2 microM and 9.2 microM against , respectively, the chloroquino sensitive FCA 20 GHA and chloroquino resistant W2 strains of Plasmodium falciparu