InChI=1S/C18H19NO7S/c1-25-15-9-5-14(6-10-15)17(20)12-19-18(21)11-4-13-2-7-16(8-3-13)26-27(22,23)24/h2-11,17,20H,12H2,1H3,(H,19,21)(H,22,23,24)/b11-4+