Showing structure for (16r,17r)-17-(3,4-dihydroxyphenyl)-5,6,16-trihydroxy-2,12,18-trioxapentacyclo[11.7.1.0³,⁸.0⁹,²¹.0¹⁴,¹⁹]henicosa-1(21),3,5,7,9,13,19-heptaen-11-one