AIDS-128372 AIDS128372 NSC268924 Secalonen B [7,7'-Bi-3H-xanthene]-4a,4'a(4H,4'H)-dicarboxylic acid, 2,2',9,9'-tetrahydro-4,4',8,8'-tetrahydroxy-3,3'-dimethyl-9,9'-dioxo-, dimethyl ester