Cytotoxic monoterpenoid indole alkaloids from Alstonia yunnanensis Diels.

Abstract The ethanol extract of the aerial parts of Alstonia yunnanensis Diels afforded five new monoterpenoid indole alkaloids, alstiyunnanenines A–E ( 1 – 5 ), along with one known compound, alstoniascholarine I ( 6 ). The structures of the isolated compounds were established based on 1D and 2D ( 1 H- 1 H COSY, HMQC, and HMBC) NMR spectroscopy, in addition to high resolution mass spectrometry. The isolated compounds were tested in vitro for cytotoxic potential using eight tumor cell lines. As a result, alkaloids 4 – 6 exhibited cytotoxicities against all tested tumor cell lines, especially against osteosarcoma cell lines (SOSP-9607, MG-63, Saos-2, M663) with IC 50 values