Quercetin

Quercetin is a plant flavonol from the flavonoid group of polyphenols. It is widely distributed among different fruits and vegetables.[1]

Dietary Sources

  • Pomegranate
  • Green tea
  • Red onion
  • Mango
  • Moringa oleifera
  • Blueberries
  • Chicory
  • Tomato
  • Apple
  • Passion Flower
  • White mulberry

Safety[2]

Healing Properties

Anti-Carcinogenic (anticancer)

Antiproliferative

Quercetin has demonstrated antiproliferative activity against colon and breast cancer cells.[3]

  • Treatment of quercetin had reduced the proliferation rates of colon HCT116 and breat MDA-MB-231 cancer cells.[3:1]

Cancer chemopreventive agent

Treatment with quercetin dihydrate has been shown to promote the killing activity of T cells on cancer cells.[4]

The growth rate of tumor volumes and masses treated with quercetin dihydrate were decreased.[4:1]

Anti-Inflammatory

Strong antiinflammatory activity.[1:1]

Anti-Infective

Antioxidant

Quercetin is one of the most potent antioxidants of plant origin.[1:2]

Quercetin has direct radical scavenging action.[1:3]

Brain Health

Neuroprotective

Several in-vitro studies have reported that quercetin demonstrates neuroprotection.[1:4]

Quercetin’s metabolites after absorption have all been shown to afford neuroprotection as well.[1:5]

Quercetin protects against progressive dopaminergic neurodegeneration.[1:6]

Neuroregeneration

Quesrcetin stimulates neuronal regeneration.[1:7]

Antioxidant

It has been shown to protect neurons from oxidative damage while reducing lipid peroxidation.[1:8]

Anti-Inflammatory / Anti-Amyloid Fibrils

In addition to its antioxidant properties, it inhibits the fibril formation of amyloid-β proteins, counteracting cell lyses and inflammatory cascade pathways.[1:9]

  • Suppresses neuroinflammatory processes by downregulating pro-inflammatory cytokines.[1:10]
  • Prevents the degradation of acetylcholine, and decreases Aβ production.[1:11]

Cognitive performance

Quercetin restores acetylcholine levels through the inhibition of hydrolysis of acetylcholine by AChE enzyme.[1:12]

Memory Enhancer

Quercetin and rutin have been reported to function as memory enhancers in scopolamine-induced memory impairment tests, thus possibly enhancing cholinergic neurotransmission.[1:13]

Psychostimulant

Heart Health / Cardiovascular Health

Antiinflammatory

Quercetin Attenuates Atherosclerotic Inflammation[5]

Anti-Atherogenic

Quercetin inhibits atherogenesis (hardening/narrowing of the arteries).[5:1]

Blood Health

Inhibits platelet aggregation.[1:14]

Metabolism

Energy Production / Mitochondrial Health

Quercetin protects against mitochondrial dysfunction.[1:15]

Quercetin stimulates mitochondrial biogenesis.[1:16]

  • Quercetin ameliorates mitochondrial dysfunction by restoring mitochondrial membrane potential, decreases ROS production, and restores ATP synthesis.[1:17]
  • It also increases the expression of AMP-activated protein kinase (AMPK), which is a key cell regulator of energy metabolism.[1:18]

Disease / Symptom Treatment

Cancer

Quercetin dihydrate has the exciting potential to be used as a cancer chemopreventive agent. Treatment with quercetin dihydrate has been shown to promote the killing activity of T cells on cancer cells.[4:2]

The growth rate of tumor volumes and masses treated with quercetin dihydrate were decreased.[4:3]

Neurodegenerative Diseases

Quercetin Disaggregates Prion Fibrils and Decreases Fibril-Induced Cytotoxicity and Oxidative Stress.[6]

Neuroinflammation

Reducing the neuroinflammatory events in microglia might afford a beneficial strategy for the prevention of the progression of inflammatory-mediated neurodegenerative disorders.[1:19]

Quercetin has been reported to have anti-inflammatory actions, and is a suitable candidate among phytochemicals for future studies on its efficacy to reverse neuroinflammation.[1:20]

Quercetin has been shown to inhibit neuroinflammation by reducing nitric oxide production, iNOS gene expression in microglia, the production of inflammatory cytokines, as well as a reduction in cytokine expression as reported from in vivo studies.[1:21]

Alzheimer’s Disease (AD)

  • Reverses histopathological hallmarks of AD[1:22]
  • Improves motor function[1:23]
  • Reduces α-synuclein fibrillization[1:24]
  • Reduces hippocampal neuronal cell death[1:25]
  • Improves synaptic plasticity[1:26]
  • Quercetin has shown therapeutic efficacy, improving learning, memory, and cognitive functions in AD.[1:27]
  • Quercetin administration reverses extracellular β-amyloidosis and decreases tauopathies, astrogliosis, and microgliosis in the hippocampus and amygdale, thus protecting cognitive and emotional function in age triple transgenic Alzheimer’s disease model.[1:28]

Quercetin interferes with the formation of neurotoxic oligomeric Aβ species and displays fibril destabilizing effects on preformed fibrillar Aβ, reversing Aβ-induced neurotoxicity.[1:29]

Parkinson’s Disease

Dopaminergic Neurodegeneration

Quercetin protects against progressive dopaminergic neurodegeneration.[1:30]

Cognitive Impairment

Ischemia

Traumatic injury (brain/spinal)

Isoquercetin improved motor functions in acute spinal cord injury.[1:31]

Huntington’s disease

Synergistic Effects

Nicotinamide adenine dinucleotide (NAD+)

Cell Protection (Helps prevent DNA damage)

Quercetin can significantly potentiate the cell protection and rescue effects of Nicotinamide adenine dinucleotide (NAD+).[7]

Quercetin has been independently shown to significantly protect cells from DNA-damaging agents and induced cell death.[7:1]

The NAD+ precursors Nicotinic acid and Nicotinamide, when administered with Quercetin significantly improved cell protection and rescue effects, plausibly due to increased intracellular NAD+ levels.[7:2]


  1. Title: Neuroprotective Effects of Quercetin in Alzheimer’s Disease
    Publication: MDPI Biomolecules
    Archive: archive, archive-mirror ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎

  2. Title: Safety Aspects of the Use of Quercetin as a Dietary Supplement
    Publication: Wiley Online Library: Molecular Nutrition & Food Research
    Archive ↩︎

  3. Title: Synthesis, Antiproliferative Activity and Radical Scavenging Ability of 5-O-Acyl Derivatives of Quercetin
    Publication: MDPI - Molecules
    Archive: archive, archive-mirror ↩︎ ↩︎

  4. Title: Quercetin inhibiting the PD-1/PD-L1 interaction for immune-enhancing cancer chemopreventive agent
    Publication: Wiley Online Library: Phytotherapy Research
    Archive ↩︎ ↩︎ ↩︎ ↩︎

  5. Title: Quercetin Attenuates Atherosclerotic Inflammation by Inhibiting Gal‐3‐NLRP3 Signaling Pathway
    Publication: Wiley Online Library ↩︎ ↩︎

  6. Title: Quercetin Disaggregates Prion Fibrils and Decreases Fibril-Induced Cytotoxicity and Oxidative Stress
    Publication: MDPI - Pharmaceutics
    Archive: archive, archive-mirror ↩︎

  7. Title: Resveratrol and Quercetin Potentiate the Cell Protection and Rescue Effects of NAD+ Precursors in HEK293 Cells Challenged by DNA Damaging Agent, N-Methyl-N′-nitro-N-nitrosoguanidine
    Publication: Sage Journals: Natural Product Communications
    Date: September 24, 2021
    Archive ↩︎ ↩︎ ↩︎