Indole alkaloids and terpenoids from _Tabernaemontana markgrafiana

The bark of Tabernaemontana markgrafiana yielded five acetylated pentacyclic triterpenes and 24 monoterpene indole alkaloids. The major triterpene was baurenyl acetate, which constituted ca 6% of the crude petrol 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 and ibogamine. Among the minor components, four new alkaloids were identified: 5,6-dehydro-coronaridine, 3R-methoxy-coronaridine, 3R-methoxyvoacangine and the 10,11-demethoxy chippiine.