InChI=1S/C21H22O5/c1-13(2)9-10-15-19(26-3)12-18(24)20(21(15)25)17(23)11-16(22)14-7-5-4-6-8-14/h4-9,11-12,22,24-25H,10H2,1-3H3/b16-11+