Five new terpenoids from the rhizomes of Isodon adenantha.

Five new terpenoids including 2 labdane diterpenoids (1 and 2), 2 ent-kaurane diterpenoids (3 and 4), and a new oleanane triterpenoid (5), along with 13 known compounds (6-18), were isolated from the ethyl acetate fraction of 70% acetone extract of the rhizomes of Isodonadenantha. Their structures were elucidated based on the analyses of spectroscopic data and comparison of their physicochemical properties. The structure of 1 was further confirmed by single-crystal X-ray diffraction. Cytotoxicity and antibacterial activities of the samples were measured by MTT method and the filter paper disk agar diffusion method. But none of them showed significant activities.