Antitumor agents. 221.1 buceracidins A and B,two new flavanones from Bucida buceras

As part of a study on antitumor agents from rainforest plants, two new flavanones, buceracidin A (1), 5,2'-dihydroxy-3-methoxy-6,7-(2' ',2' '-dimethylchromene)flavanone, and buceracidin B (2), 5,2'-dihydroxy-6,7-(2' ',2' '-dimethylchromene)flavanone, were isolated together with four known prenylated flavanones, minimiflorin (3), 3-hydroxyminimiflorin (4), 3-methoxyminimiflorin (5), and mundulinol (6), from Bucida buceras. The structures of buceracidins A and B were elucidated from detailed 2D NMR analyses. Among the six flavanones, 3, 5, and 6 were marginally cytotoxic in a human tumor cell line panel.