FMO5 and Alzheimer disease: Cytotoxic compounds then accumulate to cause protein collapse, enzyme failure, lipid breakdown,86 and cell death in various neurons, including DA-neuronal tissue (Fig. 2).87 These dysfunctions contribute to PD pathogenesis, and may also be a cause of Alzheimer’s disease (AD).88,89 Currently, NADPH oxidase (NOX) is considered the most important ROS generator,90 playing a crucial role in triggering OS and neurotoxicity.91 Mitochondria are also major producers of ROS.92,93 The electron transport chain’s complexes I and III are thought to be where most ROS is produced in mitochondria.