InChI=1S/C19H18O9/c1-2-3-4-5-6-11-7-9-19(28-11)12(8-10-25-19)26-18-15(22)13(20)14(21)16(27-18)17(23)24/h6-10,12-16,18,20-22H,1H3,(H,23,24)/b11-6+