Spirombandakamine A₃ and Cyclombandakamines A₈ and A₉, Polycyclic Naphthylisoquinoline Dimers, with Antiprotozoal Activity, from a Congolese Ancistrocladus Plant

Abstract

Spirombandakamine A3 (7) is only the third known naphthylisoquinoline dimer with a spiro-fused novel molecular framework and the first such representative to possess a relative trans-configuration at the two chiral centers in both tetrahydroisoquinoline subunits. It was found in the leaves of a botanically as yet unidentified Congolese Ancistrocladus plant, which is morphologically closely related to the Central African taxon Ancistrocladus ealaensis. Likewise isolated were the new cyclombandakamines A8 (8) and A9 (9), which belong to another most recently discovered type of unusual oxygen-bridged naphthylisoquinoline dimers and two previously described “open-chain” analogues, mbandakamines C (10) and D (11). The full absolute stereostructures of these compounds were assigned by combining spectroscopic, chemical, and chiroptical methods. Preliminary biomimetic investigations indicated that both spirombandakamine- and cyclombandakamine-type dimers result from the oxidation of their open-chain mbandakamine-type congeners. The new dimeric alkaloids 7–9 displayed potent growth-inhibitory activity against Plasmodium falciparum, the protozoal pathogen causing malaria, and moderate effects on Trypanosoma brucei rhodesiense, the parasite responsible for African sleeping sickness.

Towards an understanding of the biological activity of naphthylisoquinoline alkaloids: DNA-binding properties of dioncophyllines A, B, and C

“…They are obtained from two plant families exclusively, Ancistrocladaceae and Dioncophyllaceae, which are native to the tropical rainforests of Africa and Asia. [8][9][10][11][12] These lianas are used in traditional medicine, for example for the treatment of malaria. 13 Depending on their individual structure, several NIQs show promising activities against various pathogens causing tropical infectious diseases.…”