Redox Modulations, Antioxidants, and Neuropsychiatric Disorders

Table 3

Various biological sources of reactive species in the brain.

	Source of reactive species in the brain	Function in the brain	General role in neuropathology
Organelle	Mitochondria [7]	Generates ATP	Defect or reduction in mitochondrial complex I/II/III/IV activity
Enzyme	Monoamine oxidases (MOA-A and MOA-B) [96]	Degrades neurotransmitters	Increased or decreased activity can lead to neurotransmitter imbalances as well as excess reactive species
	Nitric oxide synthase [97]	Synthesis of nitric oxide	Production of superoxide anion during normal NO^∙ production
	Xanthine oxidase [98]	Catabolism of purines	Produces superoxide anions during normal metabolism
	Cytochrome P450 enzymes [99]	Drug metabolism; Bioactivation of neurosteroids such as dehydroepiandrosterone (DHEA); Metabolism of retinoic acid (regulates gene expression); Cholesterol turnover in the brain	Reduced DHEA levels correlated with memory impairment; Altered gene expression; Reduced cholesterol turnover leading to accumulation in the brain
Metabolism	Arachidonic acid (AA) metabolism [97]	Maintains membrane fluidity; Aids in the growth and repair of neurons; Participates in activation of enzymes to store free fatty acids in the brain (prevents oxidative damage)	Elevated AA metabolism and/or overexpression of metabolizing enzymes; Increased amounts of free fatty acids