InChI=1S/C20H28O8/c1-2-3-4-6-13(11-21)9-12-7-5-8-14(10-12)27-20-17(24)15(22)16(23)18(28-20)19(25)26/h5,7-10,15-18,20-24H,2-4,6,11H2,1H3,(H,25,26)/b13-9-