Eight new gelsedine-type oxindole alkaloids from Gelsemium elegans

Eight new gelsedine-type oxindole alkaloids and ten known analogues were isolated from the stems and leaves of Gelsemium elegans . Gelseansdine A ( 1 ) was an N 4 -deficient Gelsemium alkaloid, while gelseansdines E–H ( 12 , 14 , 16 – 17 ) represented a class of alkaloids polymerized with iridoid. Their structures were elucidated based on UV, HRESIMS, NMR spectroscopy, and electronic circular dichroism (ECD) data analyses. Additionally, the isolated compounds were screened for their inhibitory activity on macrophage M2 polarization.