Three New Illudalane Sequiterpenoids from Pteris semipinnata

The chemical investigation of the aerial parts of Pieris semipinnata resulted in the isolation of three illudalane sesquiterpenoids, namely (2R)-norpterosin B (1), (2R)-12-O-beta-D-glucopyranosylnorpterosin B (2), and semipterosin A (3), along with three known compounds. The structures of 1-3 were established by spectroscopic methods, including extensive 2D-NMR and CD analyses.