4-19-00-03953 (Beilstein Handbook Reference) 478-60-4 4H,5H-Pyrano(3,2-c)(1)benzopyran-10-carboxylic acid, 8,9-dihydroxy-2-methyl-4-oxo- BRN 0330020 Citromycetin Frequentic acid NSC 53584