Five new koumine-type alkaloids ( 1 – 5 ) along with six known ones were isolated from the roots of Gelsemium elegans . Their structures with absolute configurations were elucidated on the basis of NMR spectroscopy and electronic circular dichroism spectral analyses. The inhibitory effects of compounds 1 – 11 on the viability of three tumor cell lines (A-649, HepG2, and HuH7) were evaluated by the MTT assay. [ABSTRACT FROM AUTHOR]