InChI=1S/C20H28O4/c1-12(2)9-19(21)23-17-11-16-15(5)20(22)24-18(16)10-13(3)7-6-8-14(17)4/h8,10,12,16-18H,5-7,9,11H2,1-4H3/b13-10+,14-8+