Bisindole Alkaloids from the <i>Alstonia</i> Species: Recent Isolation, Bioactivity, Biosynthesis, and Synthesis

• Main Authors: Kamal P. Pandey, Md Toufiqur Rahman, James M. Cook
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Molecules
• Subjects: bisindole synthesis; biosynthesis; bioactivity; <i>Alstonia</i>; Apocynaceae; sarpagine
• Online Access: https://www.mdpi.com/1420-3049/26/11/3459

Bisindoles are structurally complex dimers and are intriguing targets for partial and total synthesis. They exhibit stronger biological activity than their corresponding monomeric units. Alkaloids, including those containing C-19 methyl-substitution in their monomeric units, their synthetic derivatives, and their mismatched pairs can be attractive targets for synthesis and may unlock better drug targets. We herein discuss the isolation of bisindoles from various <i>Alstonia</i> species, their bioactivity, putative biosynthesis, and synthesis. The total synthesis of macralstonidine, macralstonine, <i>O</i>-acetylmacralstonine, and dispegatrine, as well as the partial synthesis of alstonisidine, villalstonine, and macrocarpamine are also discussed in this review. The completion of the total synthesis of pleiocarpamine by Sato et al. completes the formal synthesis of the latter two bisindoles.