Isolation of bis-indole alkaloids with antileishmanial and antibacterial activities from Peschiera van heurkii (syn. Tabernaemontana van heurkii).

Extracts from leaves and stem bark of Peschiera van heurkii (Muell. Arg.) L. Allorge (syn. Tabernaemontana van heurkii Muell. Arg., Apocynaceae) have been assayed for antileishmanial and antibacterial activities. The activities were concentrated in the alkaloid fractions which yielded 20 indole and bisindole alkaloids. The strongest leishmanicidal and antibacterial activities were observed with the dimeric alkaloids conodurine (1), N-demethylconodurine (= gabunine) (2), and conoduramine (3). Weak toxicity towards macrophage host cells and strong activity against the intracellular amastigote form of Leishmania were observed for compounds 1 and 2. In vivo, 1 was less active than glucantime (= N-methylglucamine antimonate), the drug of reference, while 2 was devoid of activity at 100 mg/kg.