InChI=1S/C21H28O5/c1-14(2)15-7-9-16-6-5-13-21(3,26-20(16)24)18(22)12-11-17(10-8-15)19(23)25-4/h6,8,10,14H,5,7,9,11-13H2,1-4H3/b15-8+,17-10+/t21-/m1/s1