InChI=1S/C21H28O9/c1-2-3-10-15(12-11-14(23)9-7-5-4-6-8-13-22)29-21-18(26)16(24)17(25)19(30-21)20(27)28/h1,11-19,21,23-26H,4-9H2,(H,27,28)/b12-11+