Showing structure for (4r,8r)-2,4,15,18-tetrahydroxy-7,9-dioxapentacyclo[10.8.0.0³,¹⁰.0⁴,⁸.0¹⁴,¹⁹]icosa-1,3(10),11,14,16,18-hexaene-13,20-dione