The genus
Bousigonia, comprising two species, belongs to the Apocynaceae
family and is distributed mainly in China, Laos, and Vietnam.2
Previous chemical investigations of B. mekongensis resulted in
the isolation of two new eburnamine-aspidospermine-type
bisindole alkaloids, mekongenines A and B.3 In the course of
our ongoing work,4 we have investigated the constituents of B.
angustifolia. As a result, 29 indole alkaloids including the new
angustifonines A (1) and B (2) were isolated from the twigs
and leaves. The structures of the new bisindoles comprise the
union of a rearranged monoterpenoid quinoline and an
aspidospermine alkaloid. This paper describes the isolation
and structural elucidation of the new isolates, as well as
examines their cytotoxicities against five human tumor cell
lines.