InChI=1S/C21H28O11/c1-7-5-13-14(9(3)20(29)30-13)11(23)4-8(2)12(6-10(7)22)31-21-17(26)15(24)16(25)18(32-21)19(27)28/h5,10-18,21-26H,2-4,6H2,1H3,(H,27,28)/b7-5+