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