Quercetin

• Xanthaurin
• Cyanidanol
• Cyanidenolon 1522
• 3,3 ', 4' ,5,7- pentahydroxyflavone
• 2 - ( 3,4- dihydroxyphenyl) -3,5,7 - trihydroxy -4H- 1-benzopyran -4-one

Yellow, odorless solid

Fixed

316-317 ° C

• Insoluble in water
• Soluble in boiling ethanol, acetic acid and dilute sodium hydroxide solution.

Risk

Template: Infobox chemical / molecular formula search available

Quercetin (from the Latin quercus, oak), a yellow natural dye from the group of polyphenols and flavonoids. As pentahydroxyflavone it belongs to the subgroup of flavonols. Quercetin is an oxidation product of the dye anthocyanin cyanidin.

Occurrence

How cyanidin comes quercetin in nature as glycosides or methyl. 179 different glycosides are known for quercetin. (eg rutin or isorhamnetin ).

It is widespread in the plant kingdom and thus also in the food. Large amounts of quercetin can be found in onions, apples, broccoli or green beans that are partially destroyed, depending on the type of preparation. Also by the peeling of fruits and vegetables of the flavonoid fraction decreases drastically, because especially in the colored shells ( Flavonoids are plant pigments ) is the flavonoid high. It is also present in wine. Since quercetin is mainly found in the grape skins, the contents in red wines are higher than in white wine. In addition, also contributes a wooden barrel aging to quercetin content, because the substance is slowly passes from the wood into the wine during storage.

A high content of quercetin is found in

• Capers (1800 mg · kg -1)
• Lovage (1700 mg · kg -1)
• Tea ( Camellia sinensis)
• Onions - especially in the outermost rings ( 284-486 mg · kg -1)
• Blueberries ( cultivated 74 mg · kg -1, wild 146-158 mg · kg -1)
• Kale ( 60-110 mg · kg -1)
• Red grapes
• Apples ( 21-440 mg · kg -1)
• Chives ( 245 mg · kg -1)
• Citrus fruits
• Broccoli (30 mg · kg -1) and other green leafy vegetables
• Green beans (39 mg · kg -1)
• Cherries (32 mg · kg -1)
• Raspberries
• Black currant (69 mg · kg -1)
• Blackberries (45 mg · kg -1)
• Lingonberry ( cultivated 83-156 mg · kg -1, 121 mg · kg wild -1)
• The sweet rowan (85 mg · kg -1)
• Sea Buckthorn (62 mg / kg) and crowberry ( cultivated 53 mg / kg, wild 56 mg · kg -1).

A 2007 study found that tomatoes from organic farming 79 % more quercetin contained than in conventional farming.

Physiological significance

Quercetin are awarded far-reaching, positive physiological effects. Attention is drawn to the anti-cancer effect, which is mainly due to the antioxidant potential. Quercetin has a similar effect such as vitamins A, C and E as a radical scavenger. The exact sequence of oxidation inhibition in vivo is, however, still under discussion.

The effect of quercetin on mammals is relatively well studied. Quercetin also belongs to the group of flavonoids, however, with significantly mutagenic properties. Compared to Taxifolin Quercetin exerts a significant mutagenicity.

A toxicity in vitro model has shown that the increased or long- term administration of quercetin may be toxic.

Quercetin inhibits in vitro the effect of the drug bortezomib by direct chemical reaction between quercetin and the boronic group.