Goniomedines A and B: unprecedented bisindole alkaloids formed through fusion of two indole moieties via a dihydropyran unit.

Two novel bisindole alkaloids, goniomedines A (1) and B (2), possessing an unprecedented quebrachamine-pleioarpamine-type skeleton, in which indole moieties are fused via a dihydropyran unit, were isolated from the stem bark of Gonioma malagasy. The structures were elucidated by comprehensive analysis of MS and NMR spectroscopic data. Their absolute configurations were deduced following the comparison of experimental and theoretically calculated ECD spectra and through biogenetic considerations. Goniomedine B (2) exhibited moderate activity against Plasmodium falciparum.