This Phase 2 clinical trial investigates the neuroprotective potential of tocotrienols, a potent isoform of vitamin E, in patients with Parkinson's disease. The study is conducted by the National Neuroscience Institute in Singapore and represents a promising approach to disease modification through a well-tolerated nutritional intervention.
Tocotrienols have garnered significant attention in neurodegenerative disease research due to their superior neuroprotective properties compared to the more commonly used tocopherols. The trial addresses a critical unmet need in Parkinson's disease care: disease-modifying therapies that can slow or halt disease progression rather than merely managing symptoms.
| Field |
Value |
| NCT ID |
NCT04491383 |
| Status |
Recruiting |
| Phase |
Phase 2 |
| Study Type |
Interventional |
| Allocation |
Randomized |
| Intervention Model |
Parallel Assignment |
| Masking |
Double-Blind |
| Sponsor |
National Neuroscience Institute, Singapore |
| Intervention |
Tocotrienols (vitamin E isoform) |
| Enrollment |
60 participants |
| Start Date |
June 2020 |
| Expected Completion |
December 2025 |
| Location |
Singapore |
Oxidative stress is a central mechanism in Parkinson's disease pathogenesis. The substantia nigra pars compacta (SNc) of PD patients shows evidence of:
- Elevated ROS: Increased production of reactive oxygen species
- Lipid peroxidation: Enhanced membrane damage from oxidized lipids
- DNA oxidation: Oxidative DNA damage (8-OHdG accumulation)
- Protein oxidation: Carbonyl group formation on proteins
- Mitochondrial dysfunction: Complex I deficiency increases ROS
The dopaminergic neurons in the SNc are particularly vulnerable due to:
- High metabolic demand and oxygen consumption
- Dopamine metabolism generating ROS
- Neuromelanin accumulation
- Limited antioxidant capacity
Vitamin E exists in eight isoforms divided into two classes:
| Property |
Tocopherols |
Tocotrienols |
| Saturated side chain |
Yes |
Unsaturated (3 double bonds) |
| Tissue distribution |
Limited |
Broad, including CNS |
| Antioxidant potency |
Moderate |
10-50× more potent |
| Cholesterol-lowering |
No |
Yes |
| Neuroprotection |
Limited |
Enhanced |
The unsaturated side chain of tocotrienols provides several advantages:
- Enhanced membrane incorporation: Better integration into neuronal membranes
- Superior antioxidant recycling: More efficient regeneration after oxidation
- Broader tissue distribution: Crosses blood-brain barrier more effectively
- Anti-inflammatory effects: Potent inhibition of NF-κB signaling
Tocotrienols exert neuroprotective effects through multiple pathways:
- ROS scavenging: Direct neutralization of free radicals
- Lipid peroxidation inhibition: Prevents membrane damage
- Endogenous antioxidant enhancement: Upregulates SOD, catalase, glutathione peroxidase
- Metal chelation: Reduces iron-catalyzed oxidative damage
- NF-κB inhibition: Blocks pro-inflammatory transcription factor
- COX-2 downregulation: Reduces prostaglandin synthesis
- TNF-α modulation: Decreases pro-inflammatory cytokine production
- Microglial activation: Inhibits microglial-mediated neuroinflammation
- Complex I preservation: Protects mitochondrial electron transport
- ATP maintenance: Preserves cellular energy production
- Apoptosis inhibition: Prevents mitochondrial pathway of cell death
- Mitophagy enhancement: Promotes clearance of damaged mitochondria
- AMPK activation: Enhances cellular stress resilience
- mTOR modulation: Promotes autophagy
- SIRT1 activation: Supports cellular longevity pathways
- FOXO3a deacetylation: Enhances antioxidant gene expression
- NMDA receptor modulation: Reduces excitotoxicity
- Calcium homeostasis: Stabilizes intracellular calcium
- Autophagy induction: Enhances protein aggregate clearance
- Synaptic protection: Preserves synaptic function
| Arm |
Intervention |
Dose |
Duration |
| Active |
Tocotrienols (mixed isoforms) |
TBD |
12 months |
| Placebo |
Matching placebo |
N/A |
12 months |
- Diagnosis: Idiopathic Parkinson's disease (UK Brain Bank criteria)
- Disease stage: Hoehn & Yahr stage 1-3
- Age: 40-80 years
- Medication: Stable PD medication for ≥4 weeks
- Cognitive status: MMSE ≥24
- Allergy: Known vitamin E allergy
- Bleeding disorders: History of bleeding diathesis
- Anticoagulation: Current anticoagulant therapy
- Supplements: Concurrent antioxidant supplements
- Neurological: Severe cognitive impairment (MMSE <24)
- Medical: Significant hepatic or renal disease
- Unified Parkinson's Disease Rating Scale (UPDRS) Part III
- Change from baseline to 12 months
- Assessed in OFF and ON medication states
- Administered by certified raters
- Adverse event monitoring
- Vital signs
- Laboratory values (lipid panel, liver function)
- Bleeding risk assessment
- PDQ-39: Parkinson's Disease Questionnaire-39
- MDS-UPDRS Parts I, II, IV: Non-motor experiences, daily activities, motor complications
- MoCA: Montreal Cognitive Assessment
- Trail Making Test: Executive function assessment
- Oxidative stress markers:
- 8-OHdG (DNA oxidation)
- Malondialdehyde (lipid peroxidation)
- Total antioxidant capacity
- Inflammatory markers:
- Neurodegeneration markers:
- DaT SPECT imaging
- MRI volumetric analysis
Tocotrienols have demonstrated neuroprotection in multiple PD models:
| Model |
Findings |
| MPTP model |
Preserved TH+ neurons, improved behavior |
| 6-OHDA model |
Reduced lesion volume, enhanced DA release |
| Alpha-synuclein transgenic |
Reduced aggregation, improved survival |
| Rotenone model |
Restored mitochondrial function |
- Reduced lipid peroxidation in substantia nigra
- Preserved complex I activity
- Decreased microglial activation
- Enhanced autophagy flux
- Reduced alpha-synuclein aggregation
¶ Vitamin E and PD Risk
Epidemiological studies have examined vitamin E and Parkinson's disease risk:
| Study |
Finding |
| Health Professionals Follow-up |
High vitamin E intake associated with reduced PD risk |
| Nurses' Health Study |
Moderate association |
| Finnish Mobile Clinic |
No significant association |
| Meta-analysis |
Possible protective effect for dietary vitamin E |
Note: These studies largely examined tocopherols; tocotrienols have not been studied as extensively in humans.
Tocotrienols have a favorable safety profile at typical doses:
| Adverse Event |
Frequency |
Notes |
| Gastrointestinal upset |
Rare |
Usually mild |
| Bleeding risk |
Theoretical |
Monitor in anticoagulated patients |
| Headache |
Rare |
Usually transient |
Maximum tolerated dose in humans: ~1000mg/day
¶ Expected Outcomes and Clinical Significance
- Motor function preservation: Slower UPDRS progression vs. placebo
- Safety confirmation: Favorable safety profile in PD population
- Biomarker response: Reduction in oxidative stress markers
If successful, this trial would establish:
- Disease-modifying option: First disease-modifying nutritional intervention
- Accessible therapy: Low-cost, widely available treatment
- Combination potential: Synergy with dopaminergic medications
- Prevention approach: Potential for use in prodromal PD
| Trial |
Intervention |
Target |
Status |
| NCT04491383 |
Tocotrienols |
Antioxidant |
Recruiting |
| NCT06162013 |
NAD+ precursors |
Metabolic |
Recruiting |
| INMOND |
Inosine |
Urate |
Completed |
| TIRAMISU |
Talidomide analogs |
Neuroinflammation |
Terminated |