TY  - JOUR
A1  - Tshitenge, Dieudonné Tshitenge
A1  - Feineis, Doris
A1  - Mudogo, Virima
A1  - Kaiser, Marcel
A1  - Brun, Reto
A1  - Bringmann, Gerhard
T1  - Antiplasmodial Ealapasamines A-C,'Mixed' Naphthylisoquinoline Dimers from the Central African Liana Ancistrocladus ealaensis
JF  - Scientific Reports
N2  - 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.
KW  - structure elucidation
KW  - stereochemistry
KW  - Ancistrocladus ealaensis
KW  - dimers
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-170645
VL  - 7
IS  - 5767
ER  - 
TY  - JOUR
A1  - Bringmann, Gerhard
A1  - Ortmann, Thomas
A1  - Zagst, Rainer
A1  - Schoener, Bernd
A1  - Assi, Laurent Ake
A1  - Burschka, Christian
T1  - +/- Dioncophyllacine A, a naphthylisoquinoline alkaloid with a 4-methoxy substituent from the leaves of Triphyophyllum peltatum
N2  - The isolation and structure elucidation of rac-dioncophyllacine A from the leaves of Triphyophyllun peltatum, is described. Unlike all other naphthylisoquinoline alkaloids, this fully dehydrogenated representative has an additional methoxy group at C-4, the position of which is deduced from NOE results. Dioncophyllacine A has a 7,1' site of the biaryl axis, as in dioncophylline A. Its constitution is confirmed by an X-ray structure analysis, which shows that the crystalline form of this new alkaloid is racemic.
KW  - Dioncophyllaceae
KW  - Triphyophyllum peltaturn
KW  - Dioncophyllaceae leaves
KW  - (± )-dioncophyllacine A
KW  - naphthylisoquinoline alkaloids
KW  - structure elucidation
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31873
ER  -