InChI=1S/C20H20O10/c1-27-11-5-2-10(3-6-11)4-7-12-8-13(9-14(21)28-12)29-20-17(24)15(22)16(23)18(30-20)19(25)26/h2-9,15-18,20,22-24H,1H3,(H,25,26)/b7-4+