Scopariusins A-C (1-3), three novel rearranged ent-halimanoids with a bicycle[5.4.0]undecane ring system, two new normal ent-halimanoids (4 and 5), and a new ent-clerodanoid (6) were isolated from Isodon scoparius. Moreover, a biomimetic transformation from the ent-clerodanoid to the normal and the rearranged ent-halimane diterpenoids was successfully accomplished, which not only validated the biogenetic hypothesis in this plant but also confirmed the absolute configurations of 1 and 5.

Scopariusic acid (1), a new ent-clerodane-based meroditerpenoid with a unique cyclobutane ring and an unusual 1-octen-3-ol substituent, together with its biosynthetic related compound 2, were isolated from the aerial parts of Isodon scoparius. The structures of 1 and 2, including their absolute configurations, were determined by spectroscopic methods, single-crystal X-ray diffraction analysis, and chemical methods. Compound 1 showed weak cytotoxicity and moderate immunosuppressive activity.