Reactive Oxygen Species (Ros) is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Reactive oxygen species (ROS) are chemically reactive molecules containing oxygen that are generated as natural byproducts of cellular
metabolism, primarily through mitochondrial electron transport chain activity. While ROS serve essential physiological roles in cell
signaling, immune defense, and redox homeostasis, their excessive production or inadequate neutralization results in [oxidative stress[/mechanisms/[oxidative-stress[/mechanisms/[oxidative-stress[/mechanisms/[oxidative-stress[/mechanisms/[oxidative-stress--TEMP--/mechanisms)--FIX--
— a condition of oxidative damage to lipids, [proteins[/[proteins[/[proteins[/[proteins[/[proteins[/[proteins[/[proteins[/[proteins[/proteins, and DNA that is a hallmark feature of virtually all [neurodegenerative
diseases[/[diseases[/[diseases[/[diseases[/[diseases[/[diseases[/[diseases[/[diseases[/diseases. The brain is particularly vulnerable to oxidative stress due to its high oxygen consumption (20% of total body O₂
despite representing only 2% of body mass), abundant polyunsaturated fatty acids in neuronal membranes, high iron content in specific
regions, and relatively low antioxidant defenses compared to other organs[1]
[2]
.
ROS-mediated damage has been implicated as both an early initiating factor and a self-amplifying accelerant of neurodegeneration in [Alzheimer's disease[/diseases/[alzheimers[/diseases/[alzheimers[/diseases/[alzheimers[/diseases/[alzheimers--TEMP--/diseases)--FIX--, [Parkinson's disease[/diseases/[parkinsons[/diseases/[parkinsons[/diseases/[parkinsons[/diseases/[parkinsons--TEMP--/diseases)--FIX--,
[ALS[/diseases/[als[/diseases/[als[/diseases/[als[/diseases/[als--TEMP--/diseases)--FIX--, and [Huntington's disease[/mechanisms/[huntington-pathway[/mechanisms/[huntington-pathway[/mechanisms/[huntington-pathway[/mechanisms/[huntington-pathway--TEMP--/mechanisms)--FIX--. The concept of oxidative stress as a common pathological thread across neurodegenerative diseases has evolved considerably since the original
"free radical theory of aging" — modern understanding recognizes ROS as pleiotropic signaling molecules whose dysregulation, rather than mere overproduction, drives
pathology[3].
¶ Types and Sources of ROS
| Species |
Formula |
Half-Life |
Reactivity |
Primary Source |
| Superoxide anion |
O₂•⁻ |
~1 μs |
Moderate |
Mitochondrial Complex I and III |
| Hydrogen peroxide |
H₂O₂ |
Relatively stable (seconds–minutes) |
Low-moderate |
SOD dismutation of superoxide; NOX enzymes |
| Hydroxyl radical |
•OH |
~1 ns |
Extremely high |
Fenton reaction (Fe[2]⁺ + H₂O₂) |
| Peroxynitrite |
ONOO⁻ |
~1 s |
Very high |
Reaction of NO• + O₂•⁻ |
| Singlet oxygen |
[1]O₂ |
~1 μs |
High |
Photochemical reactions; myeloperoxidase |
| Lipid peroxyl radicals |
LOO• |
Seconds |
High |
Lipid peroxidation chain reactions |
| Hypochlorous acid |
HOCl |
Minutes |
High |
Myeloperoxidase (neutrophils, activated [microglia">4. |
- Complex III (cytochrome bc1): Generates superoxide on both sides of the inner mitochondrial membrane via the Q-cycle mechanism, releasing superoxide into both the matrix and the intermembrane space. Complex III-derived ROS can therefore directly access the cytoplasm through voltage-dependent anion channels.
- Other mitochondrial sources: α-ketoglutarate dehydrogenase (a significant ROS source in aging [neurons[/entities/[neurons[/entities/[neurons[/entities/[neurons[/entities/[neurons--TEMP--/entities)--FIX--, glycerol-3-phosphate dehydrogenase, electron transfer flavoprotein-ubiquinone oxidoreductase, and dihydroorotate dehydrogenase.
- Monoamine oxidase (MAO): Located on the outer mitochondrial membrane, MAO-A and MAO-B catalyze the oxidative deamination of monoamine neurotransmitters (dopamine, [serotonin[/entities/[serotonin[/entities/[serotonin[/entities/[serotonin[/entities/[serotonin--TEMP--/entities)--FIX--, norepinephrine), generating H₂O₂ as a stoichiometric byproduct. MAO-B-mediated dopamine catabolism is a major source of ROS in [dopaminergic neurons[/cell-types/[dopaminergic-neurons[/cell-types/[dopaminergic-neurons[/cell-types/[dopaminergic-neurons[/cell-types/[dopaminergic-neurons--TEMP--/cell-types)--FIX--.
- NADPH oxidases (NOX): A family of transmembrane enzymes (NOX1–5, DUOX1–2) that produce superoxide or H₂O₂ as their primary function. [microglia[/cell-types/[microglia[/cell-types/[microglia[/cell-types/[microglia[/cell-types/[microglia--TEMP--/cell-types)--FIX--, modulating the activity of kinases (ASK1, MEKK1), phosphatases (PTEN, PTP1B), and transcription factors ([NF-κB[/entities/[nf-kb[/entities/[nf-kb[/entities/[nf-kb[/entities/[nf-kb--TEMP--/entities)--FIX--, HIF-1α, [Nrf2[/proteins/[nrf2[/proteins/[nrf2[/proteins/[nrf2[/proteins/[nrf2--TEMP--/proteins)--FIX--).
- Synaptic plasticity: ROS, particularly superoxide and H₂O₂, are required for [long-term potentiation[/mechanisms/[long-term-potentiation[/mechanisms/[long-term-potentiation[/mechanisms/[long-term-potentiation[/mechanisms/[long-term-potentiation--TEMP--/mechanisms)--FIX-- ([LTP[/entities/[long-term-potentiation[/entities/[long-term-potentiation[/entities/[long-term-potentiation[/entities/[long-term-potentiation--TEMP--/entities)--FIX-- in the [hippocampus[/brain-regions/[hippocampus[/brain-regions/[hippocampus[/brain-regions/[hippocampus[/brain-regions/[hippocampus--TEMP--/brain-regions)--FIX--. SOD1 knockout mice show impaired [LTP[/entities/[long-term-potentiation[/entities/[long-term-potentiation[/entities/[long-term-potentiation[/entities/[long-term-potentiation--TEMP--/entities)--FIX--, demonstrating that regulated ROS production is necessary for normal synaptic function.
- [Neurogenesis[/entities/[neurogenesis[/entities/[neurogenesis[/entities/[neurogenesis[/entities/[neurogenesis--TEMP--/entities)--FIX--: Basal ROS levels regulate neural stem cell proliferation and differentiation in the [dentate gyrus[/brain-regions/[dentate-gyrus[/brain-regions/[dentate-gyrus[/brain-regions/[dentate-gyrus[/brain-regions/[dentate-gyrus--TEMP--/brain-regions)--FIX--. Both excessive and insufficient ROS impair adult neurogenesis.
- Innate immunity: The microglial respiratory burst (NOX2-derived ROS) is a primary defense mechanism against CNS pathogens, though its dysregulation in sterile [neuroinflammation[/mechanisms/[neuroinflammation[/mechanisms/[neuroinflammation[/mechanisms/[neuroinflammation[/mechanisms/[neuroinflammation--TEMP--/mechanisms)--FIX-- contributes to collateral neuronal damage.
The concept of "oxidative eustress" (beneficial ROS signaling at physiological levels, ~1–10 nM H₂O₂) versus "oxidative distress" (damaging ROS at supraphysiological levels, >100
nM H₂O₂) has replaced the simplistic view of all ROS as harmful. This distinction has important therapeutic implications: indiscriminate antioxidant therapy may disrupt essential
signaling while failing to address pathological ROS sources[3].
- Superoxide dismutase (SOD): Converts superoxide to H₂O₂ at near-diffusion-limited rates. Three isoforms serve distinct compartments:
- SOD1/proteins/sod1 (Cu/Zn-SOD): Cytoplasmic and intermembrane space. Mutations in SOD1 cause ~20% of familial [ALS, though the mechanism is gain-of-toxic-function rather than loss of dismutase activity.
- SOD2 (Mn-SOD): Mitochondrial matrix. Homozygous knockout is embryonic lethal. Heterozygous SOD2+/- mice show accelerated age-related neurodegeneration.
- SOD3 (EC-SOD): Extracellular. Protects the extracellular matrix and cell surfaces.
- Catalase: Converts H₂O₂ to water and O₂. Expressed at relatively low levels in the brain compared to liver and kidney, making the brain disproportionately reliant on glutathione peroxidase for H₂O₂ detoxification.
- Glutathione peroxidase (GPx): A family of selenoproteins that reduces H₂O₂ and lipid hydroperoxides using reduced glutathione (GSH) as an electron donor. GPx1 (cytoplasmic) and GPx4 (phospholipid hydroperoxide GPx, critical for preventing [ferroptosis) are the most important CNS isoforms.
- Thioredoxin (Trx)/peroxiredoxin (Prx) system: Reduces H₂O₂, peroxynitrite, and organic hydroperoxides. Prx3 is mitochondrial and particularly important for neuronal survival. Prx5 scavenges peroxynitrite.
- Glutathione reductase (GR): Regenerates reduced GSH from oxidized glutathione (GSSG) using NADPH, maintaining the GSH/GSSG ratio essential for redox homeostasis.
- Heme oxygenase-1 (HO-1): Nrf2-regulated enzyme that degrades heme to biliverdin (antioxidant), CO (signaling), and free iron. Upregulated in AD and PD brains as a stress response.
- Glutathione (GSH): The most abundant intracellular antioxidant (1–10 mM concentration), maintained in reduced form by glutathione reductase. GSH depletion is an early event in neurodegeneration — decreased GSH is one of the earliest detectable changes in the PD substantia nigra, preceding dopaminergic neuron loss. [neurons[/entities/[neurons[/entities/[neurons[/entities/[neurons[/entities/[neurons--TEMP--/entities)--FIX-- depend heavily on [astrocytes[/cell-types/[astrocytes[/cell-types/[astrocytes[/cell-types/[astrocytes[/cell-types/[astrocytes--TEMP--/cell-types)--FIX-- for GSH precursor supply (cysteine, via the glutamate-cystine antiporter system xc⁻).
- Vitamin E (α-tocopherol): Lipid-soluble chain-breaking antioxidant that terminates lipid peroxidation by donating a hydrogen atom to lipid peroxyl radicals. The most important antioxidant in neuronal membranes.
- Vitamin C (ascorbate): Water-soluble antioxidant concentrated in the brain (10× higher than plasma levels). Regenerates vitamin E from its radical form. Serves as an electron donor for multiple enzymatic reactions.
- Coenzyme Q10 (ubiquinone/ubiquinol): Mitochondrial electron carrier that also functions as a lipid-soluble antioxidant within the inner mitochondrial membrane. Reduced form (ubiquinol) scavenges superoxide and prevents lipid peroxidation.
- Uric acid: Peroxynitrite scavenger and transition metal chelator. Lower serum uric acid levels are associated with increased PD risk, and uric acid elevation (inosine supplementation) has been explored therapeutically.
- Melatonin: Potent antioxidant that accumulates in mitochondria, scavenging hydroxyl radicals and stimulating antioxidant enzyme expression. Melatonin levels decline with aging and in neurodegenerative diseases.
The Nrf2 (Nuclear factor erythroid 2-related factor 2) pathway is the master transcriptional regulator of the endogenous antioxidant
defense system250 cytoprotective [genes[/[genes[/[genes[/[genes[/[genes[/[genes[/[genes[/[genes[/genes.
| Category |
Key Targets |
Function |
| Antioxidant enzymes |
SOD1/2, catalase, GPx1/4, Prx1/5, Trx1 |
Direct ROS detoxification |
| Glutathione metabolism |
GCLC, GCLM, GSR, GSTs |
GSH synthesis and conjugation |
| NADPH generation |
G6PD, ME1, IDH1 |
Provides reducing equivalents for antioxidant enzymes |
| Iron metabolism |
Ferritin H/L, ferroportin, HO-1 |
Iron sequestration and export |
| Xenobiotic detoxification |
NQO1, AKR family, UGTs |
Phase II detoxification |
| Proteasomal subunits |
PSMB5, PSMA1, PSMC3 |
Enhanced proteasome capacity |
| Mitochondrial function |
NRF1, TFAM, PGC-1α co-activation |
Mitochondrial biogenesis and quality control |
Nrf2 activity declines with aging and is further impaired in neurodegenerative diseases:
- Nrf2 protein and target gene expression are reduced in AD [hippocampus[/brain-regions/[hippocampus[/brain-regions/[hippocampus[/brain-regions/[hippocampus[/brain-regions/[hippocampus--TEMP--/brain-regions)--FIX-- despite increased oxidative stress, suggesting a failure of the adaptive antioxidant response.
- In PD, nuclear Nrf2 levels are decreased in [substantia nigra[/brain-regions/[substantia-nigra[/brain-regions/[substantia-nigra[/brain-regions/[substantia-nigra[/brain-regions/[substantia-nigra--TEMP--/brain-regions)--FIX-- dopaminergic [neurons[/entities/[neurons[/entities/[neurons[/entities/[neurons[/entities/[neurons--TEMP--/entities)--FIX--.
- [astrocytes[/cell-types/[astrocytes[/cell-types/[astrocytes[/cell-types/[astrocytes[/cell-types/[astrocytes--TEMP--/cell-types)--FIX-- are the primary Nrf2-responsive cell type in the brain, providing antioxidant support to neighboring [neurons[/entities/[neurons[/entities/[neurons[/entities/[neurons[/entities/[neurons--TEMP--/entities)--FIX-- through GSH export, thioredoxin secretion, and HO-1-derived bilirubin. Astrocytic Nrf2 activation is neuroprotective in multiple disease models[7].
Polyunsaturated fatty acids (PUFAs) in neuronal membranes — particularly arachidonic acid (AA, 20:4) and docosahexaenoic acid (DHA, 22:6) — are highly susceptible to ROS attack due to their bis-allylic hydrogen atoms:
- Chain reaction: Initiation (•OH abstracts a bis-allylic H from a PUFA) → propagation (lipid radical + O₂ → peroxyl radical → abstracts H from adjacent PUFA) → termination (radical-radical recombination or chain-breaking antioxidant). A single initiation event can oxidize hundreds of lipid molecules.
- Toxic aldehydes: Lipid peroxidation generates reactive aldehydes including malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), and acrolein. 4-HNE forms covalent adducts with cysteine, histidine, and lysine residues on proteins, modifying enzyme activity and promoting [protein aggregation[/mechanisms/[protein-aggregation[/mechanisms/[protein-aggregation[/mechanisms/[protein-aggregation[/mechanisms/[protein-aggregation--TEMP--/mechanisms)--FIX--. 4-HNE and MDA are elevated 2–4 fold in AD and PD brain tissue.
- [ferroptosis[/mechanisms/[ferroptosis[/mechanisms/[ferroptosis[/mechanisms/[ferroptosis[/mechanisms/[ferroptosis--TEMP--/mechanisms)--FIX--: Iron-dependent lipid peroxidation drives [ferroptosis[/mechanisms/[ferroptosis[/mechanisms/[ferroptosis[/mechanisms/[ferroptosis[/mechanisms/[ferroptosis--TEMP--/mechanisms)--FIX--, a regulated form of cell death characterized by GPx4 inactivation and catastrophic accumulation of phospholipid hydroperoxides. [ferroptosis[/mechanisms/[ferroptosis[/mechanisms/[ferroptosis[/mechanisms/[ferroptosis[/mechanisms/[ferroptosis--TEMP--/mechanisms)--FIX-- is increasingly recognized as a major cell death pathway in neurodegeneration, distinct from [apoptosis[/entities/[apoptosis[/entities/[apoptosis[/entities/[apoptosis[/entities/[apoptosis--TEMP--/entities)--FIX-- and [necroptosis[/entities/[necroptosis[/entities/[necroptosis[/entities/[necroptosis[/entities/[necroptosis--TEMP--/entities)--FIX--[8].
- F₂-isoprostanes: Stable lipid peroxidation products formed by non-enzymatic oxidation of arachidonic acid. F₂-isoprostanes are elevated in AD CSF and serve as reliable oxidative stress biomarkers.
- Protein carbonylation: Irreversible oxidative modification (by direct metal-catalyzed oxidation of lysine, arginine, proline, threonine) that marks proteins for proteasomal degradation. Protein carbonyls are increased 2–3 fold in AD [hippocampus[/brain-regions/[hippocampus[/brain-regions/[hippocampus[/brain-regions/[hippocampus[/brain-regions/[hippocampus--TEMP--/brain-regions)--FIX-- and [cortex[/brain-regions/[cortex[/brain-regions/[cortex[/brain-regions/[cortex[/brain-regions/[cortex--TEMP--/brain-regions)--FIX--, and in PD substantia nigra[10].
Oxidative stress is one of the earliest detectable pathological changes in [Alzheimer's disease[/diseases/[alzheimers[/diseases/[alzheimers[/diseases/[alzheimers[/diseases/[alzheimers--TEMP--/diseases)--FIX--, often preceding amyloid plaque deposition by years:
- [amyloid-beta[/entities/[amyloid-beta[/entities/[amyloid-beta[/entities/[amyloid-beta[/entities/[amyloid-beta--TEMP--/entities)--FIX-- and ROS — a bidirectional relationship: [Aβ[/entities/[amyloid-beta[/entities/[amyloid-beta[/entities/[amyloid-beta[/entities/[amyloid-beta--TEMP--/entities)--FIX-- generates ROS through metal-catalyzed reactions ([Aβ[/entities/[amyloid-beta[/entities/[amyloid-beta[/entities/[amyloid-beta[/entities/[amyloid-beta--TEMP--/entities)--FIX-- binds Cu[2]
⁺ and Fe[3]
⁺ with high affinity, reducing them to Cu⁺ and Fe[2]
⁺ which undergo Fenton chemistry). Aβ42 inserts into mitochondrial membranes, disrupting electron transport chain complexes and increasing superoxide production. Conversely, ROS promote [Aβ[/entities/[amyloid-beta[/entities/[amyloid-beta[/entities/[amyloid-beta[/entities/[amyloid-beta--TEMP--/entities)--FIX-- production by upregulating [BACE1[/[CDK5[/[CDK5[/[CDK5[/[CDK5[/[CDK5[/[CDK5[/[CDK5[/CDK5 and inhibiting phosphatases ([PP2A). Oxidized tau (nitrated at Tyr29, Tyr197, Tyr394) forms more stable, protease-resistant aggregates. [Tau[/entities/[tau-protein[/entities/[tau-protein[/entities/[tau-protein[/entities/[tau-protein--TEMP--/entities)--FIX--(/proteins/tau pathology in turn impairs mitochondrial transport and function, further increasing ROS production.
- Mitochondrial dysfunction: Decreased Complex IV (cytochrome c oxidase) activity is consistently found in AD brains, platelets, and fibroblasts, increasing electron leakage. [Aβ[/entities/[amyloid-beta[/entities/[amyloid-beta[/entities/[amyloid-beta[/entities/[amyloid-beta--TEMP--/entities)--FIX-- accumulates in mitochondria and interacts with [Aβ[/entities/[amyloid-beta[/entities/[amyloid-beta[/entities/[amyloid-beta[/entities/[amyloid-beta--TEMP--/entities)--FIX---binding alcohol dehydrogenase (ABAD/HSD17B10), generating ROS. Mitochondrial dynamics (fission/fusion balance) are disrupted, with excessive fission and impaired mitophagy.
- Metal dysregulation: Altered [metal homeostasis] with accumulation of redox-active iron (up to 2-fold increase) and copper in amyloid plaques amplifies Fenton chemistry. Zinc, while not directly redox-active, accelerates [Aβ[/entities/[amyloid-beta[/entities/[amyloid-beta[/entities/[amyloid-beta[/entities/[amyloid-beta--TEMP--/entities)--FIX-- aggregation. Metal chelation has been explored therapeutically[10].
The [substantia nigra[/brain-regions/[substantia-nigra[/brain-regions/[substantia-nigra[/brain-regions/[substantia-nigra[/brain-regions/[substantia-nigra--TEMP--/brain-regions)--FIX-- pars compacta is uniquely vulnerable to oxidative stress in [Parkinson's disease[/diseases/[parkinsons[/diseases/[parkinsons[/diseases/[parkinsons[/diseases/[parkinsons--TEMP--/diseases)--FIX-- due to a convergence of risk factors:
- [dopamine[/entities/[dopamine[/entities/[dopamine[/entities/[dopamine[/entities/[dopamine--TEMP--/entities)--FIX-- metabolism: Dopamine auto-oxidation generates H₂O₂, superoxide, and highly reactive dopamine quinones that covalently modify proteins (including α-synuclein, [parkin[/proteins/[parkin[/proteins/[parkin[/proteins/[parkin[/proteins/[parkin--TEMP--/proteins)--FIX--, and DJ-1). Enzymatic dopamine catabolism by MAO-B generates H₂O₂ stoichiometrically. The substantia nigra processes more dopamine per neuron than any other brain region.
- Iron accumulation: The substantia nigra has the highest iron concentration of any brain region (~200 μg/g), and iron levels are further elevated (up to 255 μg/g) in PD substantia nigra, promoting Fenton chemistry. [Neuromelanin], the pigment that gives the SN its dark color, chelates iron — but when [dopaminergic neurons[/cell-types/[dopaminergic-neurons-snpc[/cell-types/[dopaminergic-neurons-snpc[/cell-types/[dopaminergic-neurons-snpc[/cell-types/[dopaminergic-neurons-snpc--TEMP--/cell-types)--FIX-- die, released neuromelanin-iron complexes activate [microglia, creating a feed-forward inflammatory loop[14]
[15]
.
- SkQ1 (visomitin): Plastoquinone-based mitochondria-targeted antioxidant with demonstrated efficacy in animal models of neurodegeneration and aging. Approved as eye drops (Visomitin) for dry eye in Russia.
Targeting NOX-derived ROS in neuroinflammation, without disrupting mitochondrial function:
- NOX2 inhibitors: Reduce microglial oxidative burst without affecting mitochondrial ROS. Genetic NOX2 deletion is neuroprotective in multiple disease models (MPTP parkinsonism, EAE, stroke).
- GKT137831 (setanaxib): A dual NOX1/4 inhibitor in clinical development for fibrotic diseases (IPF, primary biliary cholangitis). NOX4 is expressed in [neurons[/entities/[neurons[/entities/[neurons[/entities/[neurons[/entities/[neurons--TEMP--/entities)--FIX--, and its inhibition shows neuroprotective effects in preclinical models.
- Apocynin: A natural product NOX inhibitor that requires myeloperoxidase-mediated activation. Shows neuroprotection in MPTP and rotenone models of PD.
Reducing iron-catalyzed Fenton chemistry:
- Deferiprone: An oral, brain-penetrant iron chelator. The FAIR-PARK-II trial showed that deferiprone (30 mg/kg/day for 36 weeks) reduced substantia nigra iron content (measured by R2* MRI) in early PD but, unexpectedly, was associated with faster motor decline than placebo, possibly because chelation removed physiologically necessary iron before the neurodegenerative process was adequately controlled. This trial highlighted the complexity of iron chelation in neurodegeneration[16]
[18]
.
- RNA- and gene-based approaches: AAV-mediated delivery of Nrf2 or SOD2 to the CNS. Astrocyte-targeted Nrf2 [gene therapy[/treatments/[gene-therapy[/treatments/[gene-therapy[/treatments/[gene-therapy[/treatments/[gene-therapy--TEMP--/treatments)--FIX-- is neuroprotective in preclinical ALS and PD models, leveraging [astrocytes[/cell-types/[astrocytes[/cell-types/[astrocytes[/cell-types/[astrocytes[/cell-types/[astrocytes--TEMP--/cell-types)--FIX--' natural role as the brain's primary antioxidant-producing cells.
- [ferroptosis[/mechanisms/[ferroptosis[/mechanisms/[ferroptosis[/mechanisms/[ferroptosis[/mechanisms/[ferroptosis--TEMP--/mechanisms)--FIX-- inhibitors: Liproxstatin-1, ferrostatin-1, and their drug-like derivatives specifically inhibit ferroptotic cell death by preventing phospholipid peroxidation. These represent a targeted approach to the most damaging consequence of ROS in neurodegeneration.
- [Senolytics[/treatments/[senolytics[/treatments/[senolytics[/treatments/[senolytics[/treatments/[senolytics--TEMP--/treatments)--FIX--: Senescent cells are a major source of ROS and inflammatory cytokines in the aging brain. Senolytic drugs (dasatinib + quercetin, fisetin) that selectively eliminate senescent cells may reduce the oxidative burden in neurodegeneration.
| Biomarker |
Specimen |
Target |
Disease Associations |
| F₂-isoprostanes |
CSF, urine, plasma |
Lipid peroxidation |
Elevated in AD, PD, ALS; CSF F₂-isoprostanes correlate with AD severity |
| 8-OHdG |
CSF, urine, tissue |
DNA oxidation |
Elevated in AD, PD, HD brain and CSF |
| 8-OHG |
Tissue, CSF |
RNA oxidation |
Elevated early in AD [neurons[/entities/[neurons[/entities/[neurons[/entities/[neurons[/entities/[neurons--TEMP--/entities)--FIX--, before plaque/tangle formation |
| 4-HNE adducts |
Tissue, plasma |
Lipid peroxidation |
Elevated in AD [hippocampus[/brain-regions/[hippocampus[/brain-regions/[hippocampus[/brain-regions/[hippocampus[/brain-regions/[hippocampus--TEMP--/brain-regions)--FIX--, PD substantia nigra |
| Protein carbonyls |
Tissue, plasma |
Protein oxidation |
Elevated in AD, PD, ALS affected [brain regions[/[brain-regions[/[brain-regions[/[brain-regions[/[brain-regions[/[brain-regions[/[brain-regions[/[brain-regions[/brain-regions |
| 3-Nitrotyrosine |
Tissue, CSF |
Nitrosative stress |
Found in NFTs (AD), Lewy bodies (PD), motor neuron inclusions (ALS) |
| GSH/GSSG ratio |
Tissue, blood |
Redox status |
Decreased in PD substantia nigra, AD brain |
| MRS glutathione |
Brain (in vivo) |
Brain redox status |
Detectable by 7T MRS; decreased in AD and PD brain regions |
The study of Reactive Oxygen Species (Ros) has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying [mechanisms of neurodegeneration[/[mechanisms[/[mechanisms[/[mechanisms[/[mechanisms[/[mechanisms[/[mechanisms[/[mechanisms[/mechanisms and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
- [Treatments Index[/[treatments[/[treatments[/[treatments[/[treatments[/[treatments[/[treatments[/[treatments[/treatments
- [Abramov AY, Potapova EV, Dreher V, Bhatt DK. Role of oxidative stress in neurodegenerative disorders: a review of reactive oxygen species and prevention by antioxidants. Brain Commun. 2024;6(1)fcad356.
- [Singh S, et al. Exploring the role of reactive oxygen species in the pathogenesis and pathophysiology of Alzheimer's and [Parkinson's disease[/diseases/[parkinsons[/diseases/[parkinsons[/diseases/[parkinsons[/diseases/[parkinsons--TEMP--/diseases)--FIX-- and the efficacy of antioxidant treatment. Curr Issues Mol Biol. 2024;46(10)10950-10974. PMID: 39334797
- [Sies H, Jones DP. Reactive oxygen species (ROS as pleiotropic physiological signalling agents. Nat Rev Mol Cell Biol. 2020;21(7)363-383.
- [Lin MT, Beal MF. Mitochondrial dysfunction and oxidative stress in neurodegenerative diseases. Nature. 2006;443(7113:787-795.
- [Zuo L, Zhou T, Pannell BK, et al. Biological and physiological role of reactive oxygen species — the good, the bad and the ugly. Acta Physiol. 2015;214(3)329-348.
- [Brandes MS, Gray NE. NRF2 as a therapeutic target in neurodegenerative diseases. ASN Neuro. 2020;12:1759091419899782.
- [Cores A, et al. NRF2 regulation processes as a source of potential drug targets against neurodegenerative diseases. Biomolecules. 2020;10(6)904.
- [Stockwell BR, et al. [ferroptosis[/mechanisms/[ferroptosis[/mechanisms/[ferroptosis[/mechanisms/[ferroptosis[/mechanisms/[ferroptosis--TEMP--/mechanisms)--FIX--: a regulated cell death nexus linking metabolism, redox biology, and disease. Cell. 2017;171(2)273-285.
- [Beal MF. Oxidatively modified proteins in aging and disease. Free Radic Biol Med. 2002;32(9:797-803.
- [Nunomura A, Perry G, Aliev G, et al. Oxidative damage is the earliest event in Alzheimer's Disease. J Neuropathol Exp Neurol. 2001;60(8)759-767.
- [Bush AI. The metallobiology of [Alzheimer's disease[/diseases/[alzheimers[/diseases/[alzheimers[/diseases/[alzheimers[/diseases/[alzheimers--TEMP--/diseases)--FIX--. Trends Neurosci. 2003;26(4:207-214.
- [Devos D, Labreuche J, Rascol O, et al. Trial of deferiprone in [Parkinson's disease[/diseases/[parkinsons[/diseases/[parkinsons[/diseases/[parkinsons[/diseases/[parkinsons--TEMP--/diseases)--FIX--. N Engl J Med. 2022;387(22:2045-2055.
- [Smith RAJ, Murphy MP. Animal and human studies with the mitochondria-targeted antioxidant MitoQ. Ann N Y Acad Sci. 2010;1201:96-103.
- [Karaa A, et al. Efficacy and safety of elamipretide in individuals with primary mitochondrial myopathy. Neurology. 2023;101(3)e238-e252.
- [Szeto HH, et al. Elamipretide: a review of its structure, mechanism of action, and therapeutic potential. Int J Mol Sci. 2025;26(3)944.
- [Lynch DR, et al. Omaveloxolone for the treatment of Friedreich ataxia: clinical trial results and practical considerations. Expert Rev Neurother. 2024;24(3)251-264.
- [Zesiewicz TA, et al. Safety monitoring of omaveloxolone in Friedreich ataxia: results from one year of clinical treatment. Neurol Ther. 2025;14:749.
- [Darvesh AS, et al. The redox revolution in brain medicine: targeting oxidative stress with AI, multi-omics and mitochondrial therapies for the precision eradication of neurodegeneration. Int J Mol Sci. 2025;26(15)7498.
- [Coluzzi D, et al. Mitochondrial alterations, oxidative stress, and therapeutic implications in [Alzheimer's disease[/diseases/[alzheimers[/diseases/[alzheimers[/diseases/[alzheimers[/diseases/[alzheimers--TEMP--/diseases)--FIX--: a narrative review. Cells. 2025;14(3)229.
- [Liu Z, Zhou T, Ziegler AC, et al. Oxidative stress in neurodegenerative diseases: from molecular mechanisms to clinical applications. Oxid Med Cell Longev. 2017;2017:2525967.