Abinukitrine A, a unique 17,18-cyclolanostane triterpenoid from Abies nukiangensis.

Abinukitrine A (1), a novel triterpenoid, was isolated from Abies nukiangensis. Comprehensive spectroscopic analysis revealed that 1 is the first example of 17,18-cyclolanostane bearing a unique 6/6/6/5/3 ring system. Its absolute configuration was unequivocally assigned by Cu-Kα X-ray single-crystallography. Compound 1 showed a potent anti-hepatitis C virus (HCV) effect.