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Quercetin Articles

Aging Gracefully With Antioxidants
Nutrition Science News

For thousands of years, the Chinese have known the virtues of ginkgo. Modern research focuses on using ginkgo tree leaf extracts to improve brain function. Ginkgo contains quercetin and ginkgolides, two flavonoids that prevent oxidative damage to LDL cholesterol and blood vessels.

Quercetin Is Promising for Chronic Prostatitis
Nutrition Science News ~ April 2001

Quercetin, a naturally occurring bioflavonoid found in apples, black tea, and onions, was tested as a treatment for chronic prostatitis in a nonblinded study by researchers at the Institute for Male Urology in Encino, Calif. In the trial, an encouraging 59 percent of the subjects improved.1 In light of these results, Daniel Shoskes, M.D., and Jacob Rajfer, M.D., from the Division of Urology, Harbor UCLA Medical Center in Los Angeles, decided to do a proper double-blind test of quercetin vs. placebo.

Quercetin: A Natural Reverse Transcriptase Inhibitor
Nutrition Science News ~ March 1997

Along with synthetic protease inhibitors, drug companies are using synthetic reverse transcriptase inhibitor drugs to combat AIDS. On one hand, the possibility exists that natural protease inhibitors could help combat HIV the same way they help to prevent cancer; by the same token, it is possible that natural reverse transcriptase inhibitors could do the same.\


Quercetin Research

Vitamins and Nutrients as Primary Treatments in Experimental Brain Injury:
Clinical Implications for Nutraceutical Therapies

Brain Research 2016 (Jun 1);   1640 (Pt A):   114–129 ~ FULL TEXT

With the numerous failures of pharmaceuticals to treat traumatic brain injury in humans, more researchers have become interested in combination therapies. This is largely due to the multimodal nature of damage from injury, which causes excitotoxicity, oxidative stress, edema, neuroinflammation and cell death. Polydrug treatments have the potential to target multiple aspects of the secondary injury cascade, while many previous therapies focused on one particular aspect. Of specific note are vitamins, minerals and nutrients that can be utilized to supplement other therapies. Many of these have low toxicity, are already FDA approved and have minimal interactions with other drugs, making them attractive targets for therapeutics. Over the past 20 years, interest in supplementation and supraphysiologic dosing of nutrients for brain injury has increased and indeed many vitamins and nutrients now have a considerable body of literature backing their use. Here, we review several of the prominent therapies in the category of nutraceutical treatment for brain injury in experimental models, including vitamins (B2, B3, B6, B9, C, D, E), herbs and traditional medicines (ginseng, gingko biloba), flavonoids, and other nutrients (magnesium, zinc, carnitine, omega-3 fatty acids). While there is still much work to be done, several of these have strong potential for clinical therapies, particularly with regard to polydrug regimens.

Impact of a Complex Nutraceutical Supplement on Primary Tumour Formation
and Metastasis in Trp53+/- Cancer-prone Mice

Mutagenesis. 2014 (May);   29 (3):   177–187 ~ FULL TEXT

Quercetin has antioxidant properties and inhibits the cell cycle and metalloproteinases. It inhibits growth factors including epidermal growth factor crucial to many cancers and promotes apoptosis via activation of FOXO1. [34–37] Pomegranate can induce apoptosis in cancer cells via inhibition of insulin-like growth factor-1 (IGF-1) signalling (and other growth factors) highlighted in cancers. It also has antioxidant and anti-inflammatory properties and inhibits NF-κB. [38–40]

Quercetin Monograph
Alternative Medicine Review 2011 (Jun);   16 (2):   172–194   ~ FULL TEXT

Quercetin is categorized as a flavonol, one of the six subclasses of flavonoid compounds (Table 1). Flavonoids are a family of plant compounds that share a similar flavone backbone (a three-ringed molecule with hydroxyl [OH] groups attached). A multitude of other substitutions can occur, giving rise to the subclasses of flavonoids and the different compounds found within these subclasses. Flavonoids also occur as either glycosides (with attached sugars [glycosyl groups]) or as aglycones (without attached sugars)

Cyclopamine and Quercetin Suppress the Growth of Leukemia and Lymphoma Cells
Anticancer Research 2009 (Nov);   29 (11):   4629–4632   ~ FULL TEXT

Cyclopamine and quercetin suppressed cell growth and induced apoptosis in seven and eight cell lines respectively. Cyclopamine decreased the level of Gli1 protein, a target gene product of Hh signaling. Quercetin decreased the level of Notch1 protein and its active fragment in the DND-41 T-lymphoblastic leukemia cell line with constitutive Notch activation.

Inhibition of Protein Glycation by Skins and Seeds of the Muscadine Grape
Biofactors 2007;   30 (3):   193–200 ~ FULL TEXT

The phenolics present in seeds, catechin, epicatechin and gallic acid, all inhibited fructose mediated albumin glycation (Figure 2). The results agree with those reported by Wu and Yen [32] on the effects of catechin and epicatechin on glucose mediated protein glycation. However, the phenolics present in the skin are different than those in the seed. The skins have high levels of ellagic acid, myricetin, quercetin, and kaempferol. [24] Although not performed in this study, the previous report of Wu and Yen showed that quercetin and kaempferol decreased glucose mediated albumin glycation. Individual phenolics have distinct inhibitory properties on protein glycation, a result that has been correlated with antioxidant properties. [16] It is interesting to note that the lowest concentration for both muscadine skin and seed inhibition of albumin glycation was approximately 3 µg phenolics/ml; this demonstrates the importance of the total phenolic content, rather than individual, specific phenolics in inhibiting this non-enzymatic process.

Effect of Wine Phenolics on Cytokine-induced C-reactive Protein Expression
J Thrombosis and Hemostasis 2007 (Jun);   5 (6):   1309–1317   ~ FULL TEXT

Among the wine phenolics tested, quercetin and resveratrol, in a dose-dependent manner, suppressed cytokine-induced CRP expression. Two of the synthetic derivatives of resveratrol, R3 and 7b, elicited a fiftyfold higher suppressive effect compared with resveratrol. The inhibitory effects of resveratrol and its derivatives on CRP expression were at the level of mRNA production. Investigation of signaling pathways showed that the cytokines induced the phosphorylation of p38 and p44/42 MAP kinases. Inhibitors of p38 and p44/42 mitogen-activated protein kinase (MAPK) activation inhibited CRP expression, implicating the involvement of both pathways in cytokine-induced CRP expression. These data revealed a previously unrecognized role of the p44/42 MAPK signaling pathway in CRP expression. Wine polyphenolics or the synthetic compounds of resveratrol did not affect cytokine-activated phosphorylation of these MAPKs

The Role of Chronic Inflammation in Cardiovascular Disease and its Regulation by Nutrients
Alternative Medicine Review 2004 (Mar);   9 (1):   32–53 ~ FULL TEXT

Multiple risk markers for atherosclerosis and cardiovascular disease act in a synergistic way through inflammatory pathways. This article discusses some of the key inflammatory biochemical risk markers for cardiovascular disease; in particular, the role of three basic cell types affected by these risk markers (endothelial cells, smooth muscle cells, and immune cells), the crucial role of inflammatory mediators, nitric oxide balance in cardiovascular pathology, and the use of nutrients to circumvent several of these inflammatory pathways. Most risk markers for cardiovascular disease have a pro-inflammatory component, which stimulates the release of a number of active molecules such as inflammatory mediators, reactive oxygen species, nitric oxide, and peroxynitrite from endothelial, vascular smooth muscle, and immune cells in response to injury. Nitric oxide plays a pivotal role in preventing the progression of atherosclerosis through its ability to induce vasodilation, suppress vascular smooth muscle proliferation, and reduce vascular lesion formation. Nutrients such as arginine, antioxidants (vitamins C and E, lipoic acid, glutathione), and enzyme cofactors (vitamins B2 and B3, folate, and tetrahydrobiopterin) help to elevate nitric oxide levels and may play an important role in the management of cardiovascular disease. Other dietary components such as DHA/EPA from fish oil, tocotrienols, vitamins B6 and B12, and quercetin contribute further to mitigating the inflammatory process.

The Etiologies, Pathophysiology, and Alternative/Complementary Treatment of Asthma
Alternative Medicine Review 2001 (Feb);   6 (1):   20–47   ~ FULL TEXT

A chronic inflammatory disorder of the respiratory airways, asthma is characterized by bronchial airway inflammation resulting in increased mucus production and airway hyper-responsiveness. The resultant symptomatology includes episodes of wheezing, coughing, and shortness of breath. Asthma is a multifactorial disease process with genetic, allergic, environmental, infectious, emotional, and nutritional components. The underlying pathophysiology of asthma is airway inflammation. The underlying process driving and maintaining the asthmatic inflammatory process appears to be an abnormal or inadequately regulated CD4+ T-cell immune response. The T-helper 2 (Th2) subset produces cytokines including interleukin-4 (IL-4), IL-5, IL-6, IL-9, IL-10, and IL-13, which stimulate the growth, differentiation, and recruitment of mast cells, basophils, eosinophils, and B-cells, all of which are involved in humoral immunity, inflammation, and the allergic response. In asthma, this arm of the immune response is overactive, while Th1 activity, generally corresponding more to cell-mediated immunity, is dampened. It is not yet known why asthmatics have this out-of-balance immune activity, but genetics, viruses, fungi, heavy metals, nutrition, and pollution all can be contributors. A plant lipid preparation containing sterols and sterolins has been shown to dampen Th2 activity. Antioxidant nutrients, especially vitamins C and E, selenium, and zinc appear to be necessary in asthma treatment. Vitamins B6 and B12 also may be helpful. Omega-3 fatty acids from fish, the flavonoid quercetin, and botanicals Tylophora asthmatica, Boswellia serrata and Petasites hybridus address the inflammatory component. Physical modalities, including yoga, massage, biofeedback, acupuncture, and chiropractic can also be of help.

Effects of Daily Oral Administration of Quercetin Chalcone and Modified Citrus Pectin
on Implanted Colon-25 Tumor Growth in Balb-c Mice

Alternative Medicine Review 2000 (Dec);   5 (6):   546–552 ~ FULL TEXT

Previous research has confirmed that quercetin exhibits antitumor properties, likely due to immune stimulation, free radical scavenging, alteration of the mitotic cycle in tumor cells, gene expression modification, anti-angiogenesis activity, or apoptosis induction, or a combination of these effects. MCP has inhibited metastases in animal studies of prostate cancer and melanoma. To date, no study has demonstrated a reduction in solid tumor growth with MCP, and there is no research into the antitumor effect of QC. This study examines the effects of MCP and QC on the size and weight of colon-25 tumors implanted in balb-c mice.

Flavonoids Apigenin and Quercetin Inhibit Melanoma Growth and Metastatic Potential
International Journal of Ccancer 2000 (Aug);   87 (4):   595–600

In conclusion, quercetin and apigenin inhibit melanoma growth and invasive and metastatic potential; therefore, they may constitute a valuable tool in the combination therapy of metastatic melanoma.

Quercetin: A Review of Clinical Applications
Natural Medicine Online July 2000

Quercetin is frequently used therapeutically in allergic conditions, including asthma and hayfever, eczema, and hives. Additional clinical uses include treatment of gout, pancreatitis and prostatitis, which are also, in part, inflammatory conditions. The common link is its ability to mediate production and manufacture of pro-inflammatory compounds.

Antioxidants and Cancer III: Quercetin
Alternative Medicine Review 2000 (Jun);   5 (3):   196–208 ~ FULL TEXT

Quercetin is a flavonoid molecule ubiquitous in nature. A number of its actions make it a potential anti-cancer agent, including cell cycle regulation, interaction with type II estrogen binding sites, and tyrosine kinase inhibition. Quercetin appears to be associated with little toxicity when administered orally or intravenously. Much in vitro and some preliminary animal and human data indicate quercetin inhibits tumor growth. More research is needed to elucidate the absorption of oral doses and the magnitude of the anti-cancer effect.

Monograph:   Quercetin
Alternative Medicine Review 1998 (Apr);   3 (2):   140–143   ~ FULL TEXT

Quercetin appears to have many beneficial effects on human health, including cardiovascular protection, anti-cancer activity, anti-ulcer effects, anti-allergy activity, cataract prevention, antiviral activity, and anti-inflammatory effects.

Antioxidant Flavonoids: Structure, Function and Clinical Usage
Alternative Medicine Review 1996 (Apr);   1 (2):   103–111   ~ FULL TEXT

Flavonoids occur in most plant species, and account for a significant percentage of the chemical constituents of some; e.g. dried green tea leaves contain approximately 30% flavonoids by weight. Flavonoids have been shown to have antibacterial, anti-inflammatory, antiallergic, antimutagenic, antiviral, antineoplastic, anti-thrombotic, and vasodilatory activity. The potent antioxidant activity of flavonoids—their ability to scavenge hydroxyl radicals, superoxide anions, and lipid peroxy radicals—may be the most important function of flavonoids, and underlies many of the above actions in the body. Oxidative damage is implicated in most disease processes, and epidemiological, clinical, and laboratory research on flavonoids and other antioxidants suggest their use in the prevention and treatment of a number of these. Catechin and its derivatives, oligomeric proanthocyanidins, quercetin and quercetin chalcone, Ginkgo flavone glycosides, silymarin, and others can be utilized in preventative and treatment protocols for cardiovascular disease, cancer, inflammatory conditions, asthma, periodontal disease, liver disease, cataracts and macular degeneration.


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