Quercetin

Quercetin is a plant-derived polyphenolic flavonoid with potential chemopreventive activity. It is abundant in various plant food sources and is a significant bioflavonoid in the human diet. Quercetin exerts various biological effects, including antiproliferative, anti-inflammatory, and anti-allergy actions.

Mechanism of Action

While the precise mechanism of action is not fully understood, quercetin has been observed to exert several effects in vitro:

• Antiproliferative effects: These may result from the modulation of EGFR or estrogen-receptor mediated signal transduction pathways. Quercetin has been observed to decrease the expression of mutant p53 protein and the p21-ras oncogene, which are implicated in cell cycle regulation and tumor progression, respectively.
• Cell cycle arrest: Quercetin may induce cell cycle arrest at the G1 phase, impeding the progression of the cell cycle and potentially inhibiting the growth of cancer cells.
• Inhibition of heat shock protein synthesis: Heat shock proteins play a role in protecting cells from stress. Their inhibition by quercetin may make cells more susceptible to the effects of chemotherapeutic drugs.
• Synergy with chemotherapeutic drugs: Quercetin may enhance the effectiveness of chemotherapeutic drugs and reverse the multidrug resistance phenotype in vitro.

Anti-inflammatory and Anti-allergy Effects

Quercetin's anti-inflammatory and anti-allergy effects are thought to be mediated through the inhibition of the lipoxygenase and cyclooxygenase pathways. These enzymes play key roles in the production of pro-inflammatory mediators. By inhibiting these pathways, quercetin can potentially reduce inflammation and allergic reactions.

Food Sources

Quercetin is found in various plant-based foods, including apples, onions, berries, red wine, and green tea. Dietary supplements of quercetin are also available.

Further Research

While quercetin's potential health benefits are promising, more research is needed to establish its effectiveness and safety in humans, particularly in relation to its potential chemopreventive properties.

See Also

• Flavonoid
• Chemoprevention
• Bioflavonoid

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