Schilancitrilactones A–C: Three Unique Nortriterpenoids from Schisandra lancifolia

Three unique nortriterpenoids, schilancitrilactones A–C (<b>1</b>–<b>3</b>), were isolated from the stems of Schisandra lancifolia. Compound <b>1</b> possesses a 5/5/7/5/5/5-fused hexacyclic ring system with a C₂₉ backbone, while <b>2</b> and <b>3</b> feature a C₂₇ skeleton with a 5/7/5/5/5-fused pentacyclic ring system. Their absolute stereochemistries were established by CD and single-crystal X-ray diffraction experiments. Compound <b>3</b> showed anti-HIV-1 activity with an EC₅₀ value of 27.54 μg/mL, and <b>1</b> exhibited antifeedant activity at 15.73 μg/cm<sup>2