An investigation of the monoamine oxidase inhibition properties of pyrrolo[3,4‐f]indole‐5,7‐dione and indole‐5,6‐dicarbonitrile derivatives

Hit, Lead & Candidate Discovery In recent studies, we have shown that pyrrolo[3,4‐f]indole‐5,7‐dione and indole‐5,6‐dicarbonitrile derivatives act as good potency in vitro inhibitors of the monoamine oxidase (MAO) enzymes. To expand on these series and to further derive structure‐activity relationships (SARs) for MAO inhibition, in the present study we synthesized additional homologs and related analogs of these chemical classes. Analyzes of the MAO inhibition properties of the synthesized compounds show that among the pyrrolo[3,4‐f]indole‐5,7‐dione derivatives good potency MAO inhibitors exist as exemplified by 10, which possesses IC50 values for the inhibition of MAO‐A and MAO‐B of 0.023 and 0.178 µM, respectively. Among thirteen pyrrolo[3,4‐f]indole‐5,7‐diones, nine compounds exhibit IC50 values for the inhibition of an MAO isoform in the submicromolar range. It may be concluded that active MAO inhibitors, such as 10 represent suitable leads for the development of drugs for neurodegenerative and neuropsychiatric disorders such as Parkinson's disease and depression. MAO inhibitors are also of interest for the treatment of prostate cancer, certain types of cardiomyopathies and Alzheimer's disease.