5,6,10,15-tetrahydroxy-8-oxatetracyclo[8.7.0.0^{2,7}.0^{12,17}]heptadeca-1(17),2(7),3,5,12,15-hexaen-14-one
5,6,10,15-tetrahydroxy-8-oxatetracyclo[8.7.0.02,7.012,17]heptadeca-1(17),2(7),3,5,12,15-hexaen-14-one
5,6,10,15-tetrahydroxy-8-oxatetracyclo[8.7.0.0²,⁷.0¹²,¹⁷]heptadeca-1(17),2(7),3,5,12,15-hexaen-14-one