Bioactive indole alkaloids isolated from .

Bioassay-guided fractionation was conducted on a CHCl-soluble extract of the stem bark of (Apocynaceae) collected in Vietnam using the HT-29 human colon cancer cell line, and led to the isolation of a new sarpagine-type indole alkaloid (), together with nine known alkaloids, including four macroline-derived alkaloids (), a sarpagine-type alkaloid (), and four macroline-pleiocarpamine bisindole alkaloids (). The structure of the new compound () was determined on the basis of spectroscopic data interpretation. Compounds were evaluated for their NF-κB (p65) inhibitory activity against the Hela cells in an ELISA assay. The new sarpagine alkaloid, (4)-methyltalpinine (), was found to show significant NF-κB inhibitory activity (ED = 1.2 µM). Furthermore, all the isolates () were evaluated for their antileishmanial activity, and compounds ( and ) exhibited leishmaniacidal activity against promastigotes of .