Inhibition of monoamine oxidase by benzoxathiolone analogues.

Inhibitors of the monoamine oxidase (MAO) enzymes are considered useful therapeutic agents, and are used in the clinic for the treatment of depressive illness and Parkinson's disease. In addition, MAO inhibitors are also under investigation for the treatment of certain cardiovascular pathologies and as possible aids to smoking cessation. In an attempt to discover novel classes of compounds that inhibit the MAOs, the current study examines the human MAO inhibitory properties of a small series of 2H-1,3-benzoxathiol-2-one analogues. The results show that the benzoxathiolones are potent MAO-B inhibitors with IC50 values ranging from 0.003 to 0.051 μM. Although the benzoxathiolones are selective for the MAO-B isoform, two compounds display good MAO-A inhibition with IC50 values of 0.189 and 0.424 μM. Dialysis studies show that a selected compound inhibits the MAOs reversibly. It may thus be concluded that the benzoxathiolone class is suitable for the design and development of MAO-B inhibitors, and that in some instances good MAO-A inhibition may also be achieved.