Kleinhospitines A-D, new cycloartane triterpenoid alkaloids from Kleinhovia hospita.

Kleinhospitines A-D, four unprecedented cycloartane triterpenoid alkaloids possessing a spiro α,β-unsaturated γ-lactamlactone side chain, were isolated as two mixtures of C-23 epimers from Kleinhovia hospita. Kleinhospitines C and D represent the first examples of naturally occurring cycloartane triterpenoids with a 9α,10α-cyclopropyl ring. The structures and absolute configurations were determined on the basis of spectroscopic analyses and comprehensive quantum chemical calculations. The two mixtures showed hepatoprotective activity against H2O2-induced oxidative damages on primary cultured rat hepatocytes with EC50 values of 167.0 and 126.5 μM.