Sphenadilactones A and B, two novel nortriterpenoids from Schisandra sphenanthera - Xiao, W L; Pu, J X; Chang, Y; Li, X L; Huang, S X; Yang, L M; Li, L M; Lu, Y; Zheng, Y T; Li, R T; Zheng, Q T; Sun, H D (Org Lett, 2006)