1-Naphthacenecarboxylic acid, 6,11-dihydro-6,11-dioxo-2-ethyl-5,7,9-trihydroxy-, methyl ester 4-10-00-04135 (Beilstein Handbook Reference) 749-18-8 BRN 2711377 Bisanhydropyrromycinone Cyclacidin Methyl 6,11-dihydro-6,11-dioxo-2-ethyl-5,7,9-trihydroxy-1-naphthacenecarboxylate pi-Pyrromycinone