New Labdane Diterpenes and Their Glycoside Derivatives from the Roots of Isodon adenantha.

Two new labdane-type diterpenes (adenanthic acids A and B; 1 and 2, resp.) and three new labdane diterpene glycosides (adenanthosides A-C; 3-5, resp.) were isolated from the roots of Isodon adenantha, together with 23 known constituents including seven diterpenoids (6-12), eight triterpenoids (13-20), one lignan glycoside (21), six steroids (22-27), and one ceramide (28). Their structures were elucidated by spectroscopic methods including extensive 2D-NMR techniques. Cytotoxicity and antibacterial activities of the samples were measured by the MTT method and the filter paper disc agar diffusion method. But none of them showed significant activities.