Quercetin

Quercetin is a plant-derived flavonol found in many fruits and vegetables. Its chemical structure gives it pigment properties and the ability to act as an antioxidant.

Flavonol: A class of flavonoids with a 3-hydroxyflavone backbone, commonly found in plants. Quercetin is one member of this structurally defined class.
Antioxidant: A substance that slows oxidation by reacting with oxidants or interrupting oxidation chains. Quercetin can donate electrons or hydrogen atoms to reactive species.
Dietary supplement: A product intended to add nutrients or other substances to the diet. Quercetin is sold in supplements at doses that can exceed ordinary food intake.
Phenylpropanoid pathway: A plant metabolic pathway that produces phenolic compounds from phenylalanine-derived precursors. This pathway supplies the precursors used to build quercetin.
Flavonoid: A large class of plant polyphenols with a shared carbon-based skeleton and diverse biological roles. Flavonols such as quercetin belong to this broader family.
Oxidative stress: A state in which oxidant production exceeds the capacity of biological systems to control it. Quercetin's antioxidant activity is often studied in relation to this imbalance.
Bioavailability: The fraction of an administered substance that reaches systemic circulation in an active form. Absorption and metabolism determine how much ingested quercetin reaches the body.
Chalcone: An open-chain flavonoid intermediate with two aromatic rings joined by a three-carbon bridge. Plant enzymes convert chalcone intermediates into the flavonoid framework of quercetin.
Polyphenol: A broad group of compounds containing multiple phenol-like structural units, common in plants. Quercetin's multiple hydroxylated rings make it a plant polyphenol.
Chelation: The binding of a metal ion by a molecule through multiple coordination sites. Quercetin can bind certain metal ions, affecting reactions that generate oxidants.

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