The bark of Tabernaemontana markgrafiana yielded five acetylated penta
cyclic triterpenes and 24 monoterpene indole alkaloids. The major trit
erpene was baurenyl acetate, which constituted ca 6% of the crude petr
ol extract. An X-ray study of iso-ursenyl acetate was carried out for
the first time. The indole alkaloids were primarily of the iboga-type
and constituted ca 3% of the dried bark and 20% of the total extracts.
The major alkaloids were coronaridine, (19S)-heyneanine, voacangine a
nd ibogamine. Among the minor components, four new alkaloids were iden
tified: 5,6-dehydro-coronaridine, 3R-methoxy-coronaridine, 3R-methoxyv
oacangine and the 10,11-demethoxy chippiine.