Bisleuconothines B–D, Modified Eburnane–Aspidosperma Bisindole Alkaloids from Leuconotis griffithii

Three new bisindole alkaloids, bisleuconothines B–D ( 1 – 3 ), were isolated from the bark of Leuconotis griffithii . Their structures were elucidated by 1D and 2D NMR spectroscopy and DFT calculations. Bisleuconothine B ( 1 ) is the first monoterpene indole alkaloid dimer featuring bridges between both C-16–C-10′ and C-2–O–C-9′. All compounds were deemed noncytotoxic (IC 50 > 10 μM) when tested against A549 human lung adenocarcinoma cells.