MEDICINAL-PLANTS FROM PAPUA-NEW-GUINEA .3. INDOLE ALKALOIDS WITH INVITRO ANTIPROLIFERATIVE ACTIVITY FROM THE AMMONIACAL EXTRACT OF NAUCLEA-ORIENTALIS

Nine angustine-type alkaloids were isolated from ammoniacal extracts o f Nauclea orientalis L. (Rubiaceae). Three of them, 10-hydroxyangustin e and the two diastereoisomeric 3,14-dihydroangustolines, have not bee n described in the literature thus far. The structures of the isolates were determined with spectroscopic methods, mainly 1D- and 2D-NMR spe ctroscopy. The compounds were found to exhibit in vitro antiproliferat ive activity against the human bladder carcinoma T-24 cell line and ag ainst EGF (epidermal growth factor)-dependent mouse epidermal keratino cytes. By using overpressure layer chromatography, it was shown that m inor quantities of these alkaloids occur in dried Nauclea orientalis l eaves. The use of ammonia in the extraction process results in a signi ficant increase in the formation of angustine-type alkaloids from stri ctosamide-type precursors.