Assembling of phenyl substituted halogens in the C3-position of substituted isatins by mono wave assisted synthesis: development of a new class of monoamine oxidase inhibitors.

A series of ten chloro- and bromo-substituted isatin derivatives were synthesized and evaluated for their ability to inhibit the monoamine oxidase (MAO) enzymes. All compounds demonstrated more potent inhibition of MAO-A compared to MAO-B. The most potent MAO-A inhibitor was HIB2 (IC = 0.037 μM), followed by HIB4 (IC = 0.039 μM), while HIB10 (IC = 0.125 μM) exhibited the most potent inhibition of MAO-B. HIB2 was identified as a specific MAO inhibitor with a selectivity index of 29 for MAO-A over MAO-B. The enzyme-inhibitor dissociation constants (K) for HIB2 and HIB10 were 0.031 μM and 0.036 μM, respectively, for MAO-A and MAO-B. Both HIB2 and HIB10 exhibited competitive and reversible inhibition. An analysis of the ADMET and PAMPA suggested that HIB2 is permeable to the blood-brain barrier (BBB). Molecular docking analysis revealed that HIB2 forms stable hydrogen bonds with Asn181 and Gln215 in the MAO-A ligand-protein complex. Dynamic analysis indicated the stability of HIB2 with MAO-A. These findings suggest that HIB2 is potent reversible MAO-A inhibitor, making this class of compounds potential therapeutic agents for neurological disorders.