InChI=1S/C20H20O10/c21-11-5-3-9(4-6-11)1-2-10-7-12(22)14(23)13(8-10)29-20-17(26)15(24)16(25)18(30-20)19(27)28/h1-8,15-18,20-26H,(H,27,28)/b2-1+