Cytotoxic gelsedine-type indole alkaloids from Gelsemium elegans

A chemical investigation on the 95% ethanol extract of the aerial part of Gelsemium elegans resulted in the isolation of three new gelsedine-type indole alkaloids, 14β-hydroxygelselenidine (1), 11-methoxygelseziridine (2), and 14β-hydroxygelsedethenine (3). Structural elucidation of all the compounds was accomplished by spectral methods such as 1 D and 2 D NMR, IR, UV, and HRESIMS. The isolated compounds were tested in vitro for cytotoxic activities against five human non-small-cell lung cancer cell lines. Consequently, alkaloid 3 exhibited cytotoxic activities for all tested tumor cell lines with IC50 values from 8.3 to 9.8 μM.