New and Bioactive Sesquiterpenes from Schisandra sphenanthera

Three new sesquiterpenes, schisansphenins A (1) and B (2) and (−)‐γ‐cuparenol (3), were isolated from an acetone extract of the fruits of Schisandra sphenanthera. The known compound 4 was isolated for the frist time from a natural source. The structures of the isolated compounds were elucidated through extensive spectroscopic analyses, particularly 2D‐NMR experiments (1H,1H‐COSY, HMQC, HMBC, and NOESY). A plausible biogenetic pathway for schisansphenin B (2) is proposed. Compounds 2 and 3 significantly reduced activation of NF‐AT and NF‐κB in the luciferase‐reporter assay.