Schilancitrilactones A–C: Three Unique Nortriterpenoids from Schisandra lancifolia

Three unique nortriterpenoids, schilancitrilactones A–C (1–3), were isolated from the stems of Schisandra lancifolia. Compound 1 possesses a 5/5/7/5/5/5-fused hexacyclic ring system with a C29 backbone, while 2 and 3 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 3 showed anti-HIV-1 activity with an EC50 value of 27.54 μg/mL, and 1 exhibited antifeedant activity at 15.73 μg/cm2.