Bioactivities and synthesis of indoloquinoline alkaloids: Cryptolepine, isocryptolepine and neocryptolepine

Abstract

Tetracyclic heteroaromatic compounds with linear or angularly fused indoloquinoline ring systems constitute an important structural moiety in natural products. The indoloquinoline alkaloids cryptolepine, isocryptolepine (cryptosanguino-lentine) and neocryptolepine (cryptotackieine) are three of the thirteen characterized alkaloids isolated from the roots of the West African shrub Cryptolepis sanguinolenta. They are important due to their wide spectrum of biological properties. These alkaloids possess an interesting anti-plasmodial activity against chloroquine-resistant P. falciparum and are known to intercalate in the DNA double helix resulting in dramatic changes in DNA conformation, thus inhibits the DNA replication and transcription. This chapter describes the brief biological activities and various important synthetic methods developed for the preparation of cryptolepine 1. isocryptolepine 2 and neocryptolepine 3 during recent years.