Flavonoids are found in most plant material. The most important dietary sources are fruits, tea and soybean. Green and black tea contains about 25% percent flavonoids. Flavonoids have powerful antioxidant properties, and are becoming very popular because they have many health promoting effects. Some of the activities attributed to flavonoids include: anti-allergic, anti-cancer, antioxidant, anti-inflammatory and anti-viral. The flavonoids quercetin is known for its ability to relieve hay fever, eszema, sinusitis and asthma, and for reducing the risk for cancer, and protection against osteoporosis. Consumption of red wine, red grape juice, grape skin and grape seeds has been linked to many health benefits. There are mainly two grape phytochemicals responsible for these benefits: proanthocyanidins and resveratrol. Proanthocyanidins are in the first place very strong antioxidants. Studies have shown that proanthocyanidins act as anti-cancer and anti-allergic agents, and that they improve heart health.
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Table 1. Flavonoid Subclasses and Examples
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Subclass
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Selected Examples
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Flavones
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Apigenin, Chrysin, Luteolin
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Flavonols
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Kaempferol, Myricetin, Quercetin
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Flavanones
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Hesperidin, Naringenin
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Flavanols (also called catechins)
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Epicatechin, Gallocatechin
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Anthocyanidins
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Cyanidin, Malvidin, Pelargonidin
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Anthocyanidins
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Cyanidin, Malvidin, Pelargonidin
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Isoflanones
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Genistein, Daidzein
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FROM: Quercetin Monograph
Alternative Medicine Review 2011 (Jun); 16 (2): 172194
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Dietary Flavanols Restore Hippocampal-dependent Memory
in Older Adults with Lower Diet Quality and
Lower Habitual Flavanol Consumption
Proc Natl Acad Sci 2023 (Jun 6); 120 (23): e2216932120 Dietary flavanols are food constituents found in certain fruits and vegetables that have been linked to cognitive aging. Previous studies suggested that consumption of dietary flavanols might specifically be associated with the hippocampal-dependent memory component of cognitive aging and that memory benefits of a flavanol intervention might depend on habitual diet quality. Here, we tested these hypotheses in the context of a large-scale study of 3,562 older adults, who were randomly assigned to a 3-y intervention of cocoa extract (500 mg of cocoa flavanols per day) or a placebo [(COcoa Supplement and Multivitamin Outcomes Study) COSMOS-Web, NCT04582617]. Using the alternative Healthy Eating Index in all participants and a urine-based biomarker of flavanol intake in a subset of participants [n = 1,361], we show that habitual flavanol consumption and diet quality at baseline are positively and selectively correlated with hippocampal-dependent memory. While the prespecified primary end point testing for an intervention-related improvement in memory in all participants after 1 y was not statistically significant, the flavanol intervention restored memory among participants in lower tertiles of habitual diet quality or habitual flavanol consumption. Increases in the flavanol biomarker over the course of the trial were associated with improving memory. Collectively, our results allow dietary flavanols to be considered in the context of a depletion-repletion paradigm and suggest that low flavanol consumption can act as a driver of the hippocampal-dependent component of cognitive aging.
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Medicarpin and Millepurpan, Two Flavonoids Isolated from
Medicago sativa, Induce Apoptosis and Overcome
Multidrug Resistance in Leukemia P388 Cells
Phytomedicine. 2015 (Dec 1); 22 (13): 11861194
These data indicate that medicarpin and millepurpan possess pro-apoptotic properties and potentiate the cytotoxicity of chemotherapy drugs in multidrug resistant P388 leukemia cells by modulating P-gp-mediated efflux of drugs. These flavonoids may be used as chemopreventive agents or as sensitizer to enhance cytotoxicity of chemotherapy drugs in multidrug resistant cancer cells.
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Neuroinflammatory Processes in Cognitive Disorders: Is There
a Role for Flavonoids and N-3 Polyunsaturated Fatty Acids
in Counteracting Their Detrimental Effects?
Neurochem Int. 2015 (Oct); 89: 6374
We will also detail the current evidence indicating that flavonoids and n-3 polyunsaturated fatty acids are strong candidates in preventing neuroinflammation and modulating age-related memory decline, and we will describe the potential mechanisms of action underlying their neuroprotective effects. As such, these dietary bioactives represent important precursor molecules in the quest to develop a new generation of drugs capable of counteracting neuroinflammation and neurodegenerative diseases.
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Flavonoid-based Therapies in the Early Management
of Neurodegenerative Diseases
Adv Nutr. 2015 (Jan 15); 6 (1): 6472
During the past several years, there has been enormous progress in the understanding of the causative factors that initiate neuronal damage in various neurodegenerative diseases, including Alzheimer disease, Parkinson disease, multiple sclerosis, amyotrophic lateral sclerosis, and Huntington disease. Preventing neuronal damage and neuronal death will have a huge clinical benefit. Regular consumption of flavonoids has been associated with a reduced risk of neurodegenerative diseases. In addition to their antioxidant properties, these polyphenolic compounds exhibit neuroprotective properties by their interaction with cellular signaling pathways followed by transcription and translation that mediate cell function under both normal and pathologic conditions. This review focuses on human intervention studies as well as animal studies on the role of various flavonoids in the prevention of neurodegenerative diseases.
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Quercetin Monograph
Alternative Medicine Review 2011 (Jun); 16 (2): 172194 ~ 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)
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Effect of Cocoa Products on Blood Pressure:
Systematic Review and Meta-analysis
American Journal of Hypertension 2010 (Jan); 23 (1): 97103
The evidence supporting the antihypertensive effects of cocoa has been building over the last few years, and this systematic review and meta-analysis of 10 randomized controlled trials, comprising 297 individuals confirms the BP-lowering capacity of flavanol-rich cocoa products. The high level of flavanols found in the cocoa plant is believed to be responsible for the lowering of blood pressure.
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Flavonoids: Recent Advances as Anticancer Drugs
Recent Pat Anticancer Drug Discov 2010 (Jun); 5 (2): 152164
Flavonoids belong to polyphenolic secondary metabolites with broad-spectrum pharmacological activities and extensive biological effects, and the most prominent activity is their potential role as anticancer agents. In recent years, flavonoids and their synthetic analogues have been intensely investigated in the treatment of ovarian, breast, cervical, pancreatic, and prostate cancer.
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Cyclopamine and Quercetin Suppress the Growth of
Leukemia and Lymphoma Cells
Anticancer Res 2009 (Nov); 29 (11): 46294632
Cyclopamine and quercetin suppress the growth of a number of leukemia and lymphoma cells. This finding suggests the potential use of these compounds in molecularly-targeted therapy for leukemia and lymphoma.
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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): 546552 ~ 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.
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Flavonoids Apigenin and Quercetin Inhibit Melanoma Growth
and Metastatic Potential
Int J Cancer 2000 (Aug); 87 (4): 595600
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.
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Antioxidants and Cancer III: Quercetin
Alternative Medicine Review 2000 (Jun); 5 (3): 196208 ~ 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.
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Oligomeric Proanthocyanidin Complexes: History, Structure,
and Phytopharmaceutical Applications
Alternative Medicine Review 2000 (Apr); 5 (2): 144151 ~ FULL TEXT
Considerable recent research has explored therapeutic applications of oligomeric proanthocyanidin complexes (OPCs), naturally occurring plant metabolites widely available in fruits, vegetables, nuts, seeds, flowers, and bark. OPCs are primarily known for their antioxidant activity. However, these compounds have also been reported to demonstrate antibacterial, antiviral, anticarcinogenic, anti-inflammatory, anti-allergic, and vasodilatory actions. In addition, they have been found to inhibit lipid peroxidation, platelet aggregation, capillary permeability and fragility, and to affect enzyme systems including phospholipase A2, cyclooxygenase, and lipoxygenase.
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Flavonoids Inhibit Cell Growth and Induce Apoptosis
in B16 Melanoma 4A5 Cells
Biosci Biotechnol Biochem 2000 (Sep); 64(9): 181320
We investigated the growth inhibitory activity of several flavonoids, including apigenin, luteolin, kaempherol, quercetin, butein, isoliquiritigenin, naringenin, genistein, and daizein against B16 mouse melanoma 4A5 cells.
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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.
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Monograph: Quercetin
Alternative Medicine Review 1998 (Apr); 3 (2): 140143 ~ 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.
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Antioxidant Flavonoids: Structure, Function and Clinical Usage
Alternative Medicine Review 1996 (Jul); 1 (2): 103111 ~ FULL TEXT
Flavonoids have been shown to have anti-bacterial, anti-inflammatory, antiallergic, antimutagenic, antiviral, antineoplastic, anti-thrombotic, and vasodilatory activity.
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