Plant anticancer agents III: Isolation of indole and bisindole alkaloids from Tabernaemontana holstii roots.

Certain active antileukemic and cytotoxic fractions prepared from Tabernaemontana holstii roots were investigated, resulting in the isolation of the known indole alkaloids conoduramine, conodurine, coronaridine, gabunine, 19-oxocoronaridine, pericyclivine, perivine, and vobasine. Two new alkaloids were assigned the structures 19-oxoconodurine and 19-(2-oxopropyl)conodurine. Both gabunine and 19-(2-oxopropyl)conodurine showed significant inhibitory activity against P-388 cell culture. All of the alkaloids are reported for the first time from T. holstii; conodurine, conoduramine, gabunine, perivine, and pericyclivine are reported for the first time from any Tabernaemontana species.