OBJECTIVES Quercetin is a flavonoid and an important dietary constituent of fruits and vegetables. In recent years, several pharmacological activities of quercetin, such as its neuroprotective activity and, more specifically, its anti-convulsant effects in animal models of epilepsy, have been reported. This study evaluated the role of quercetin pretreatment on gene expression of γ-amino butyric...

We investigated a molecular mechanism underlying quercetin-mediated amelioration of colonic mucosal injury and analyzed chemical structure contributing to the quercetin's effect. Quercetin up-regulated vascular endothelial growth factor (VEGF), an ulcer healing factor, not only in colon epithelial cell lines but also in the inflamed colonic tissue. VEGF derived from quercetin-treated colon epit...

Miconia langsdorffii Cogn. (Melastomataceae), Roupala montana Aubl. (Proteaceae), Struthanthus syringifolius (Mart.) (Loranthaceae), and Schefflera vinosa (Cham. & Schltdl.) Frodin (Araliaceae) are plant species from the Brazilian Cerrado whose schistosomicidal potential has not yet been described. The crude extracts, fractions, the triterpenes betulin, oleanolic acid, ursolic acid and the flav...

Hydroxycinnamic acids and flavonoids are dietary phenolic antioxidants that are abundant in our diet. Hydroxycinnamic acids are highly sulfated in vivo, and sulfotransferases (SULTs), in particular SULT1A1, play a major role in their metabolism. Flavonoids are potent inhibitors of human SULTs. In this study, the potential metabolic interaction between dietary hydroxycinnamic acids and flavonoid...

It has recently been shown by Hollman et al. (Am. J. Clin. Nutr., 62, 1276-1282) that flavonoid glycosides are preferentially absorbed from dietary onions compared to the flavonoid aglycone. In the light of this, we have compared the bioactivities of the two most abundant flavonoid glycosides that we have purified from onions (quercetin-3,4'-diglucoside and quercetin-4'-glucoside) to the querce...

Quercetin is one of the naturally occurring dietary flavonol compounds. It is present abundantly in plants and has chemopreventive and anticancer effects. To investigate its anticancer mechanism, we examined the activity of quercetin against acute leukemia cell line, HL-60. Our results showed that quercetin inhibited cell proliferation and induced apoptosis in a time- and dose-dependent manner....

Quercetin is a dietary polyphenolic compound with potentially beneficial effects on health. Claims that quercetin has biological effects are based mainly on in vitro studies with quercetin aglycone. However, quercetin is rapidly metabolized, and we have little knowledge of its availability to tissues. To assess the long-term tissue distribution of quercetin, 2 groups of rats were given a 0.1 or...

A high-throughput method for the extraction and analysis of quercetin in human plasma using 96-well SPE and LC-(ESI)MS/MS (7 min/run) is described. Quercetin exists as a range of glycosides in foods. The dominant types of quercetin glycosides vary depending on genetics (i.e., species and cultivar). Dietary sources include onions and apples (i.e., the peel). Herein the quercetin glycoside compos...

Some intervention studies have shown that quercetin supplementation can regulate certain biomarkers, but it is not clear how the doses given relate to dietary quercetin (e.g. from onion). We conducted a two-period, two-sequence crossover study to compare the bioavailability of quercetin when administered in the form of a fresh red onion meal (naturally glycosylated quercetin) or dietary supplem...

12 Some intervention studies have shown that quercetin supplementation can regulate certain biomarkers, 13 but it is not clear how the doses given relate to dietary quercetin (e.g. from onion). We conducted a 14 two-period, two-sequence crossover study to compare the bioavailability of quercetin when 15 administered in the form of fresh red onion meal (naturally glycosylated quercetin) or dieta...