Showing structure for 2,3,11,15,16-pentahydroxy-9,13,17-trimethyl-4,12-dioxo-5,18-dioxapentacyclo[12.5.0.0¹,⁶.0²,¹⁷.0⁸,¹³]nonadecan-7-yl 2-methylbut-2-enoate