Spectral characteristics of C-methylflavones

A study has been made of natural C-methylflavones and their dealkylated analogues: 5-hydroxy-4′,7-dimethoxy-7-methylflavone (noreucalyptin); 4′,5,7-trihydroxy-6-methylflavone; 5-hydroxy-4′,7-dimethoxy-6,8-dimethylflavone (eucalyptin); 4,′5-dihydroxy-7-methoxy-6,8-dimethylflavone (sideroxylin); 4′,5,7-trihydroxy-6,8-dimethylflavone; 4′,5,6-trihydroxy-3-methoxy-8-methylflavone (silpin) and 3,4′,5,6-tetrahydroxy-8-methylflavone.