Quercetin, derive

Because of the advantageous dietary effects of flavonoids they have been vigorously investigated in food and food products. The objectives of these measurements were the separation and quantitation of well-known flavonoids in foods and the identification of new flavonoids. An HPLC-ESI MS method has been developed for the isolation and identification of new quercetin derivatives in the leaves of Eruca sativa (Mill). Fresh leaves (500g) were homogenized with 1 200 ml of methanol-water (7 3, v/v), the suspension was macerated for 24h at ambient temperature, then it was filtered, concentrated to 50 ml and diluted with water to 500 ml. The extract was applied to an Amberlite XAD-2 column (75 X 8cm i.d.) and was washed subsequently with 11 of water and 11 of diethyl ether. The glucoside fraction was eluted with 1.51 of methanol and the eluate was concentrated in vacuum and liophilized. 

A one-electron oxidation study of quercetin (see structure below) and quercetin derivatives (rutin) by DPBH, CAN, or dioxygen in protic and aprotic solvents has shown that quercetin radicals quickly disproportionate to generate quercetin and produce a quinone. This quinone adds water molecules and is then degraded. Oligomerization might be a minor route in media of low water content. Oxidation of quercetin-serum albumin complex retarded water to the quercetin quinone. The role of the quercetin 3-OH was established as follows (1) allows the formation of jo-quinonoid compounds, quickly converted into solvent adducts which still react with one-electron oxidants, and (2) in its deprotonated form stabilizes radicals, allowing autoxidation to proceed under mild conditions. 

Aura, A.M., O Leary, K.A., Williamson, G., Ojala, M., Bailey, M., Puupponen-Pimia, R., Nuutila, A.M., Oksman-Caldentey, K.M., and Poutanen, K., Quercetin derivatives are deconju-gated and converted to hydroxyphenylacetic acids but not methylated by human fecal flora in vitro, J. Agric. Food Chem., 50, 1725, 2002. 

Aura, A.M. et al.. Quercetin derivatives are deconjugated and converted to hydroxyphenylacetic acids but not methylated by human fecal floral in vitro, J. Agric. Food Chem., 50, 1725, 2002. 

As with the corresponding flavones, aerial parts of Thymus hirtus (Lamiaceae) afforded p-OH-benzyl derivatives of kaempferol and quercetin, respectively. Earlier, Haplopappm foUosus (Asteraceae) was reported to accumulate haplopappin, a phenylethyl substituted quercetin derivative. Similar substituted flavones have also been found mainly to occur in members of Lamiaceae and Asteraceae (see Table 12.3), thus being probably chemosyste-matically significant accumulation trends. 

The physiological effects of the kaempferol and quercetin derivatives are uncertain they inhibited indole-3-acetic acid oxidase in vitro they may induce dormancy, uncouple oxidative phosphorylation, stimulate plant... 

The drug contains peculiar chemical constituents such as naphtodianthrones (hypericins), acylphloroglucinols (hyperforins), flavonol glycosides (quercetin derivatives) and biflavones [9] and all the metabolites as a whole seem to contribute to its pharmacological activity. Current use of St. John s Wort is mainly for the treatment of mild to moderate depression [10,3] and drug extracts for antidepressant applications have become increasingly popular. 

The absorption of flavonoids from food was recently studied by Hollman et al [146], who studied the absorption of onion quercetin derivatives after the administration of onion. To circumvent the problem... 

White wines contain cinnamic acids, / -conmaric acid and caffeic acid, with traces of fernlic acid. These are present in free form and in combination with tartaric acid (coutaric and caftaric acids) (Riberean-Gayon, 1965). They are involved in the browning of white grape must (Cheynier et al., 1995). White wines also contain quercetin derivatives, catechins and procyanidins. 

N. Sassi, L. Biasutto, A. Mattarei, M. Carraro, V. Giorgio, A. Citta, P. Bemardi, S. Garbisa, I. Szabo, C. Paradisi, and M. Zoratti, Cytotoxicity of a mitochondriotropic quercetin derivative mechanisms. Biochim. Biophys. Acta., 1817 (2012) 1095-106. 

Phytochemistry The herb contains glycosides, which are produced after the enzymic hydrolysis of mustard essential oil. Seeds contain 12-19 % drying oil. There is a possibility for the presence of prussic acid in young plants in the spring (Khalmatov 1964). The plant contains the flavonoid lepidoside (Fursa and Litvinenko 1970). The seeds were found to contain quercetin derivatives, as well as 18.71 % oil, in which alpha-linolenic, oleic, erucic and eicosenoic add were the most abundant (Dolya et al. 1973a, b). 

Brazil is home to exotic fruits with imique chemical and sensory attributes. A great number of them are underexploited native fruits, with great potential for international markets. Another particularity of Brazilian native fruits is their riehness in flavonol, mainly quercetin derivatives, when compared to well-known fruit sources such as apples (Genovese et al. 2008 Aheme and O Brien 2002). Despite their vast potential, little is known about their functionality and bioactive ingredients. Some of these fruits are listed in Table 21.2 and will be presented below. 

Coquinho Butia capitata Becc.) or coquinho-azedo comes from the south of Brazil and is normally consumed fresh or as a liqueur. The pulp contains high levels of oil (2.5%), dietetic fiber (7.0%), pro-vitamin A (146.2 RAE/100 g), vitamin C (approximately 50 mg/100 g), potassium (516 mg/100 g), and phenolic compounds (210-260 mg/100 g, with approximately 3 mg/100 g FW of quercetin derivatives) (Faria eta/. 2008 Genovese et al. 2008). 

Ozga J.A., Saeed A., Wismer W., Reinecke D.M. Characterization of cyanidin- and quercetin-derived flavonoids and other phenolics in mature Saskatoon fruits (Amelanchier alnifolia Nutt.). Journal of Agricultural and Food Chemistry, 55 10414-10424 (2007). 

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