Antiplasmodial Ealapasamines A-C,‘Mixed’ Naphthylisoquinoline Dimers from the Central African Liana Ancistrocladus ealaensis

Autor: Dieudonné Tshitenge Tshitenge, Doris Feineis, Virima Mudogo, Marcel Kaiser, Reto Brun, Gerhard Bringmann
Jazyk: angličtina
Rok vydání: 2017
Předmět:
Zdroj: Scientific Reports, Vol 7, Iss 1, Pp 1-9 (2017)
Druh dokumentu: article
ISSN: 2045-2322
DOI: 10.1038/s41598-017-05719-w
Popis: Abstract Three unusual heterodimeric naphthylisoquinoline alkaloids, named ealapasamines A-C (1–3), were isolated from the leaves of the tropical plant Ancistrocladus ealaensis J. Léonard. These ‘mixed’, constitutionally unsymmetric dimers are the first stereochemically fully assigned cross-coupling products of a 5,8′- and a 7,8′-coupled naphthylisoquinoline linked via C-6′ in both naphthalene portions. So far, only two other West and Central Ancistrocladus species were known to produce dimers with a central 6,6″-axis, yet, in contrast to the ealapasamines, usually consisting of two 5,8′-coupled monomers, like e.g., in michellamine B. The new dimers 1–3 contain six elements of chirality, four stereogenic centers and the two outer axes, while the central biaryl axis is configurationally unstable. The elucidation of the complete stereostructures of the ealapasamines was achieved by the interplay of spectroscopic methods including HRESIMS, 1D and 2D NMR (in particular ROESY measurements), in combination with chemical (oxidative degradation) and chiroptical (electronic circular dichroism) investigations. The ealapasamines A-C display high antiplasmodial activities with excellent half-maximum inhibition concentration values in the low nanomolar range.
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