Synthesis and Monoamine Oxidase Inhibitory Activity of Halogenated Flavones.

Small molecule neurotransmitters containing amines are metabolized by monoamine oxidase (MAO) in the nervous system. Monoamine oxidase inhibitors are a valuable class of drugs prescribed for the management of neurological disorders, including depression. A series of halogenated flavonoids similar to the dietary flavonoid acacetin were designed as selective MAO-B inhibitors. MAO-A and -B inhibition of 36 halogenated flavones were tested. The halogens (fluorine and chlorine) were placed at positions 5 and 7 on ring A of the flavone scaffold. All compounds were selective MAO-B inhibitors with micro- and nanomolar IC 50 values. Compounds 9f , 10a - c , 11a - c , 11g , h , and 11l displayed inhibitory activity toward MAO-B with IC 50 values between 16 to 74 nM. We conclude that halogenated flavonoids are promising molecules in pursuit of developing new agents for neurological disorders.