Two New Megastigmane Glycosides and a New Iridoid Glycoside from Gelsemium elegans

Two new megastigmane glycosides, eleganosides A and B (1 and 3, resp.), and one new iridoid glycoside, gouwenoside A (4), together with two known compounds, foliasalacioside B, (2) and loganin (5), were isolated from the aerial parts of Gelsemium elegans (GARDN. et CHAMP.) BENTH. (Loganiaceae). Their structures were elucidated by spectroscopic methods including 1D- and 2D-NMR techniques. The absolute configuration of 1 was determined by CD spectroscopy.