Structural characterization of schintrilactone, a new class of nortriterpenoids from Schisandra chinensis.

Two new nortriterpenoids, designated as schintrilactones A (1) and B (2), with modified five-membered D ring and delta-lactone E ring, were isolated from Schisandra chinensis. Their structures were determined to have a unique carbon skeleton by elucidation of spectroscopic evidence and density functional theory calculations of circular dichroism. Schintrilactones A and B occur as a pair of configurationally unstable and thus slowly interconverting diastereomers.