Showing structure for 6,7-dihydroxy-21-methoxy-17,17-dimethyl-10,12,16-trioxapentacyclo[11.8.0.0³,¹¹.0⁴,⁹.0¹⁵,²⁰]henicosa-1(21),3(11),4(9),5,7,13,15(20),18-octaen-2-one