Bisleuconothines B–D, Modified Eburnane–Aspidosperma Bisindole Alkaloids from <i>Leuconotis griffithii</i>

Abstract

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 (IC₅₀ > 10 μM) when tested against A549 human lung adenocarcinoma cells.