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Updated: Jan 2, 2026
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A Plate-Based Assay for the Measurement of Endogenous Monoamine Release in Acute Brain Slices
Published on: August 11, 2021
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Monoamine oxidase inhibition by selected dye compounds
Franciska de Beer1, Jacobus P Petzer1,2, Anél Petzer1,2
1Centre of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa.
Chemical Biology & Drug Design
|December 14, 2019
Summary
Researchers identified three novel dye compounds—acridine orange, oxazine 170, and Darrow red—as potent inhibitors of monoamine oxidase (MAO). These dyes show promise for developing new treatments for neurological and psychiatric disorders.
Area of Science:
- Biochemistry
- Pharmacology
- Neuroscience
Background:
- Monoamine oxidase (MAO) enzymes are crucial in regulating neurotransmitters and are implicated in neurodegenerative and psychiatric conditions.
- Methylene blue and its metabolite azure B are known MAO-A inhibitors, suggesting potential for related compounds as therapeutic agents.
Purpose of the Study:
- To screen a library of 22 structurally related dyes for their inhibitory effects on human MAO-A and MAO-B.
- To identify novel, potent, and selective MAO inhibitors for potential therapeutic development.
Main Methods:
- Enzyme inhibition assays were performed on human MAO-A and MAO-B using 22 different dye compounds.
- Inhibitory concentrations (IC50) and mechanisms (competitive, reversible) were determined for active compounds.
Main Results:
- Acridine orange selectively inhibited MAO-A (IC50 = 0.017 μM).
- Oxazine 170 selectively inhibited MAO-B (IC50 = 0.0065 μM).
- Darrow red exhibited non-specific inhibition of both MAO-A (IC50 = 0.059 μM) and MAO-B (IC50 = 0.065 μM), demonstrating higher potency than methylene blue.
Conclusions:
- Acridine orange, oxazine 170, and Darrow red are potent, competitive, and reversible inhibitors of human MAO isoforms.
- These identified dyes represent promising lead compounds for the future design of MAO inhibitors and warrant further preclinical investigation.
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