The inhibitory effects of flavonoids on monoamine oxidases (MAOs) have attracted great interest since alterations in monoaminergic transmission are reported to be related to neurodegenerative diseases such as Parkinson's and Alzheimer's diseases and psychiatric disorders such as depression and anxiety thus MAOs may be considered as targets for the treatment of these multi-factorial diseases. In the present study four Sideritis flavonoids xanthomicrol (1) isoscutellarein 7-O-[6'''-O-acetyl--d-all ...