Showing structure for methyl 10,11,15,16-tetrahydroxy-9,13-dimethyl-3-[(3-methylbut-2-enoyl)oxy]-4-oxo-5,18-dioxapentacyclo[12.5.0.0¹,⁶.0²,¹⁷.0⁸,¹³]nonadecane-17-carboxylate