InChI=1S/C19H18O8/c1-26-16-9-12(3-6-14(16)21)10-17(19(24)25)27-18(23)7-4-11-2-5-13(20)15(22)8-11/h2-9,17,20-22H,10H2,1H3,(H,24,25)/b7-4+