Four new steroid saponins with highly oxidized side chains from the leaves of Vernonia amygdalina

Vernoamyosides A-D (1-4), four new Δ7, 9(11) stigmastane-type steroid saponins were isolated from the dried leaves of an African medicinal plant Vernonia amygdalina Delile (Asteraceae). Their structures were determined by a combination of spectroscopic analyses (HR-ESI-MS, 1D/2D NMR) and by chemical methods. These four new compounds possessed highly oxidized side chains (C-20-C-29), and formed complex ring systems in 2-4. The inhibitory effects on NO production in lipopolysaccharide-activated RAW264.7 macrophages of these new compounds were tested.