Monoamine oxidase B (MAO-B)

Overview

Monoamine oxidase B (MAO-B) is a mitochondrial enzyme that catalyzes the oxidative deamination of monoamine neurotransmitters and biogenic amines. This enzymatic reaction generates hydrogen peroxide as a byproduct, linking MAO-B activity to oxidative stress in neural and peripheral tissues 41962139Apr. MAO-B plays a critical role in neurotransmitter metabolism and has emerged as a significant therapeutic and diagnostic target in neurodegenerative diseases 41475227Dec. The enzyme is selectively expressed in astrocytes, microglia, and certain neuronal populations, and its upregulation is associated with reactive astrogliosis and pathological inflammation 42366728Jun. Beyond neurodegeneration, recent evidence indicates that MAO-B is pathologically upregulated in peripheral nervous system tissues, making it relevant to metabolic complications including diabetic peripheral neuropathy 41857368Mar.

Recent Publications Summary

Recent studies have continued to position monoamine oxidase B (MAO-B) as a therapeutic and diagnostic target in neurodegenerative disease research. A machine learning-driven screening effort used curated ChEMBL data to develop QSAR classifiers for dual MAO-B/Sig-1R modulation, focusing on indole/oxindole scaffolds with piperazine motifs and identifying structural features associated with activity; virtual screening of natural compounds was then performed using these models 42412605Jul. In parallel, medicinal chemistry work on fluorinated indazole-5-carboxamide derivatives yielded a highly potent and MAO-A-selective inhibitor, compound 32, which also served as the basis for a PET tracer candidate with favorable radiosynthesis, brain penetration, and selegiline-blockable binding in rat brain 42366728Jun.

Several studies explored MAO-B inhibition in the context of Alzheimer’s disease and related neurodegenerative mechanisms. Hydrazide-hydrazone indole congeners were optimized as multi-target ligands against AChE, BACE1, and MAO-B, with in vitro, in vivo, and in silico profiling used to identify promising derivatives for Alzheimer’s disease therapy 41865568Mar. Natural products from Fernandoa adenophylla were also evaluated against BACE-1 and MAO-B, with peshawaraquinone reported as a strong MAO-B inhibitor and enzyme kinetic, docking, and DFT analyses supporting target engagement 42032388Apr. In another study, a previously identified 5-substituted-1H-indazole MAO-B inhibitor was incorporated into nanostructured lipid carriers to improve delivery; this formulation increased blood-brain barrier crossing compared with the free compound and preserved antioxidant efficacy 41962139Apr.

MAO-B has also been linked to disease mechanisms beyond Alzheimer’s disease. In diabetic peripheral neuropathy, MAOB—but not MAOA—was found to be pathologically upregulated in sciatic nerve and dorsal root ganglion tissues from patients and model mice, and the selective MAOB inhibitor Khellin alleviated DPN-like pathology in mice through a pathway involving HIF-1α/BACE1/Aβ/NLRP3/tau 41857368Mar. Separately, a dual-signal ratiometric fluorescence and colorimetric assay was developed for MAO-B sensing by coupling MAO-B-catalyzed phenethylamine oxidation to hydrogen peroxide generation and downstream signal amplification via Fe/Co/Cu layered double hydroxide nanosheets and carbon dots, enabling sensitive MAO-B detection across a broad concentration range 41475227Dec.

What Changes, What Holds

1. MAO-B remains a drug target, but the new chemistry mainly refines how to modulate and image it rather than changing its biological role
REINFORCES Machine-learning screening and fluorinated indazole chemistry extend the established view of MAO-B as a therapeutic and diagnostic target in neurodegenerative disease 42412605Jul42366728Jun. The added value is practical: the work sharpens structure–activity expectations for dual MAO-B/Sig-1R ligands and supports PET-tracer development, but it does not alter the baseline account of MAO-B as an enzyme linked to oxidative stress and disease relevance.

2. MAO-B inhibitor development is being pushed toward multi-target and delivery-focused strategies, not a new disease role
REINFORCES Hydrazide-hydrazone indole ligands, natural-product screening, and lipid-carrier formulation all stay within the baseline framework of MAO-B as a neurodegeneration-relevant target 41865568Mar42032388Apr41962139Apr. What changes is the therapeutic strategy: the recent work emphasizes multi-target design, natural-product leads, and improved brain delivery. None of this displaces the established account; it strengthens the case that MAO-B inhibition can be integrated into broader Alzheimer’s disease drug-development programs.

3. MAO-B is now implicated in diabetic peripheral neuropathy and can be measured with a new sensing platform
NEW DIRECTION The diabetic peripheral neuropathy findings extend the baseline statement that MAO-B is upregulated in peripheral nervous system tissues by tying that upregulation to a specific disease mechanism and inhibitor-responsive pathology 41857368Mar. That adds a new clinically relevant role beyond the neurodegenerative focus of the Overview. The fluorescence/colorimetric assay is a separate methodological advance for detecting MAO-B activity 41475227Dec, useful for study and monitoring but not a change in biology.

Overview update candidates: MAO-B involvement in diabetic peripheral neuropathy; MAO-B sensing assay as a new measurement method.