InChI=1S/C21H20O10S/c1-10(9-29-32(26,27)28)4-5-13-12(3)19-17(7-16(13)24)30-20-14(8-22)15(23)6-11(2)18(20)21(25)31-19/h4,6-8,23-24H,5,9H2,1-3H3,(H,26,27,28)/b10-4+