Preparative separation of four isomers of synthetic anisodamine by HPLC and diastereomer crystallization.

Anisodamine (654-1), a well-known cholinergic antagonist, is marketed as synthetic anisodamine (mixture of four isomers, 654-2) in China. To preparative resolution and comparison of the bioactivities of the four isomers of synthetic anisodamine, current work explores an economic and effective separation method by using preparative high performance liquid chromatography (HPLC) and diastereomer crystallization. Their absolute configurations were established by single-crystal X-ray diffraction and circular dichroism method. The purities of each isomer were more than 95%. Among them, 654-2-A2 (6R, 2'S configuration) exhibited better effect on cabachol preconditioned small intestine tension more than 654-2 and other isomers. The direct separation method without using HPLC was tried as well, which was still on progress. This is the first report of the method for preparative separation of four isomers of synthetic anisodamine which could be used for large-scale production in industry.