Flavonol quercetin

The chemical formulae for a variety of plant phenols are given in Fig. 16.2, including examples of simpler phenols, such as cinnamic acid derivative, and of tocopherols, flavonoids, flavonoid glycosides and anthocyanidins. The flavonoids include the following subclasses flavanones (taxifolin), flavones (luteolin), flavonols (quercetin) and flavanols (catechin/epicatechin). The... 

Flavonols Quercetin Onions 21.4 US Department of Agriculture 2007a... 

Hollman PC, van Trijp JM, Mengelers MJ, de Vries JH and Katan M B. 1997. Bioavailability of the dietary antioxidant flavonol quercetin in man. Cancer Lett 114(1—2) 139—140. 

Jimenez M and Garcia-Carmona F. 1999. Oxidation of the flavonol quercetin by polyphenol oxidase. J Agric Food Chem 47(l) 56-60. 

Flavonols Quercetin, kaempferol, myricetin, isorhamnetin, Apples, berries, broccoli, cabbages, chives, cranberries, grapes, kale, onions, peppers, spinach, Swiss chard, tomatoes, watercress... 

Balasubramanian S, Govindasamy S. 1996. Inhibitory effect of dietary flavonol quercetin on 7,12-dimethylbenz[a]anthracene-induced hamster buccal pouch carcinogenesis. Carcinogenesis 17(4) 877-879. 

UV-Vis linear dichroism and (mid-)IR ATR IR analysis have been used to explain the possible association between DNA and the flavonols quercetin, rutin (quercetin-3-rutino-side), and morin (3,5,7,2, 4 -pentahydroxyflavone) in solution.These nucleophilic flavonoids were shown to bind DNA by intercalation with an interaction having similar nature and geometry however, under comparable conditions, quercetin exhibited a greater number... 

Solimani, R., The flavonols quercetin, rutin and morin in DNA solution UV-vis dichroic (and mid-infrared) analysis explain the possible association between the biopolymer and a nucleophilic vegetable-dye, Biochim. Biophys. Acta, 1336, 281, 1997. 

Green chilli pepper is one of the few vegetables to contain both flavonols (quercetin, 11.39 mg/100 g) and flavones (luteolin, 2.7 mg/100 g) at detectable levels. Celery and sweet ball peppers are the main food sources of flavones independent of flavonols. 

Tea is the only analyzed beverage to contain (-)-epigallocatechingallate (EGCG) in quantifiable amounts. EGCG and (—)-epicatechingallate (ECG) are the most abundant forms, each contributing 27% to the total catechin content (22.2 mg/100 ml) of black tea. Three flavonols (quercetin, kaempferol, and myricetin) are also found in tea. For example, 100 g of decaffeinated tea contains 5.2 mg quercetin, 2.4 mg kaempferol, and 0.1 mg myricetin. 

Flavonols (quercetin + kaempferol + myricetin) Flavones (apigenin + luteolin)... 

Hakkinen, S.H. et al., Content of the flavonols quercetin, myricetin, and kaempferol in 25 edible berries, J. Agric. Food Chem., 47, 2274, 1999. 

Recently, Limtrakul et al. [214] have shown that flavonols quercetin (29) and kaempferol (28), and isoflavones genistein (42) and daidzein (40), markedly increase the sensitivity of the multidrug-resistant human cervical carcinoma KB-VI cells to vinblastine and paclitaxel. The flavonols inhibited P-gp activity in MDR KB-V1 cells more efficiently than isoflavones. 

Hertog MGL and Hollman PCH, Potential health effects of the dietary flavonols quercetin. EurJ Clin Nutr 50 63-71 (1996). 

Flavonols Quercetin Yellow onions, curly kale, broccoli, blueberry,... 

Stilbene (resveratrol) Flavonol (quercetin) Isoflavone (genistein)... 

Verma, A.K. et al., Inhibition of 7,12-dimethylbenz(a)-anthracene- and N-nitrosom-ethylurea-induced rat mammary cancer by dietary flavonol quercetin. Cancer Res., 48, 5754, 1988. 

The first chemical constituent was isolated from podophyllin in 1880 and named podophyllotoxin (97). A structure was proposed in 1932 and after some fine-tuning (98) was shown to be the lignan (60). As might be expected, the crude resin contains a variety of chemical types, including the flavonols quercetin and kaempferol (99). Although these other constituents undoubtedly have biological activity, it is the lignans that have received most attention and to which we shall devote the remainder of this section. 

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