Cycloartane Triterpenoids from <i>Kleinhovia hospita</i>

Four new cycloartane triterpenoids, together with the known gardenolic acid B, were isolated from Kleinhovia hospita. The triterpenoids (1-3) contain a unique 21,23-diacetal side-chain, while compound 4 contains two alpha,beta-unsaturated ketone moieties. Their structures and relative configurations were determined by spectroscopic methods, including 2D NMR and IR. These compounds showed promising hepatoprotective effects on nitrofurantoin-induced cytotoxicity in human liver-derived Hep G2 cells.