InChI=1S/C20H20O10/c21-11-5-9(6-12(22)7-11)1-2-10-3-4-13(8-14(10)23)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+