Two new bisindole alkaloids, angustifonines A (1) and B (2), comprising the union of a rearranged
monoterpenoid quinoline and an aspidospermine alkaloid, as well as 27 known indole alkaloids were isolated from the twigs and
leaves of Bousigonia angustifolia. Their structures and absolute configurations were elucidated by a combination of MS, NMR, and
computational methods. Angustifonines A and B exhibited cytotoxicity against various human cancer cell lines with IC50 values of
2.71−16.22 μM. A possible biosynthesis pathway toward the new bisindole alkaloids 1 and 2 is presented.