Four New Flavones and a New Isoflavone from <i>Iris bungei</i>

Four new irisflavones A-D (1-4) and irilin D (5) have been isolated from the underground parts of Iris bungei along with known isoflavones, irilins A-B (6-7) and tlatancuayin (8). The structures of the new compounds were determined using NMR and mass spectroscopic methods and were found to be 2',5,7-trihydroxy-3,6-dimethoxyflavone (1), 2',5-dihydroxy-3,6,7-trimethoxyflavone (2), 2',5,6'-trihydroxy-3,6,7-trimethoxyflavone (3), 3,3',5-trihydroxy-2',7-dimethoxyflavone (4), and 3',4',5,7-tetrahydroxy-6-methoxyisoflavone (5). The structures of irisflavones 1, 3, and 4 were confirmed by single-crystal X-ray diffraction studies.