The Alstoscholarisine Alkaloids: Isolation, Structure Determination, Biogenesis, Biological Evaluation, and Synthesis.

The alstoscholarisines are a small family of biologically and structurally interesting polycyclic monoterpenoid indole alkaloids isolated from the leaf extracts of Alstonia scholaris. The alkaloids can be divided into three different subtypes based upon their structures and putative biogenesis: (1) (-)-alstoscholarisines A-E, (2) (+)-alstoscholarisine G, and (3) (+)-alstoscholarisines H-J. This review discusses the isolation, structure determination, biological activity, and proposed biosynthesis of these metabolites. In addition, synthetic studies on the alkaloids are described including total syntheses of racemic alstoscholarisines A-E, a total synthesis of (-)-alstoscholarisine A, and a synthesis of racemic alstoscholarisine H.