InChI=1S/C20H28O4/c1-3-19(22)14-11-12-16-20(23)15-10-8-6-4-5-7-9-13-17-24-18(2)21/h3,10,15,19-20,22-23H,1,4-9,13,17H2,2H3/b15-10+