Cytotoxic caged tetraprenylated xanthonoids from Garcinia gaudichaudii (Guttiferae) - Cao,S.-G.; Wu,X.-H.; Sim,K.-Y.; Tan,B.KH.; Pereira,J.T.; Wong,W.H.; Hew,N.F.; Goh,S.H. (Tetrahedron Lett, 1998)