First Example of Diterpenoids from 14,15‐Cyclopimarane in the Roots of Linum usitatissimum

Chemical investigation of the roots of Linum usitatissimum led to the isolation and characterization of a new diterpenoid, named usitatissimin A ( 1 ), together with four known compounds. The structure of the new compound was established by spectroscopic methods, including X‐ray crystallographic diffraction analysis that confirmed the relative configuration of 1 . This is the first example of a diterpenoid with a novel 6/6/6/3‐membered ring system of 14,15‐cyclopimarane. In addition, usitatissimin A showed pronounced hepatoprotective activity against D ‐galactosamine‐induced toxicity in WB‐F344 rat hepatic epithelial stem‐like cells.