Quercetin-3-sulfate

The main kaempferol metabolite in human plasma is the 3-glucuronide. The three major metabolites of quercetin are quercetin-3-glucuronide, quercetin-3 -sulfate, and iso-rhamnetin-3-glucuronide (found at 0.1 to 1 iuM). These are accompanied by lesser amounts of the 4 -glucuronides of quercetin and isorhamnetin, and several uncharacterized metabol-... 

Flavonoids (quercetin 3-sulfate, quercetin Dye from Flaveria Pre-Columbian Andean APCI operating in positive- and negative-ion... 

Acetyltrisulfate quercetin] (sulfated flavone) Acteoside (= Verbascoside Kusaginin)... 

Quaternary ammonium compounds biocidal activity mechanism, 1, 401 toxicity, 1, 124 Quaternization heterocyclic compounds reviews, 1, 73 ( )-Quebrach amine synthesis, 1, 490 Queen substance synthesis, 1, 439 4, 777 Quercetin occurrence, 3, 878 pentamethyl ether photolysis, 3, 696 photooxidation, 3, 695 Quercetrin hydrolysis, 3, 878 Quinacetol sulfate as fungicide, 2, 514 Quinacridone, 2,9-dimethyl-, 1, 336 Quinacridone pigments, 1, 335-336 Quinacrine... 

Mild extraction was also found to be effective in the analysis of extracts of Flaveria haumanii, l in which quercetin, kaempferol, isorhamnetin as well as their glycosides and sulfate esters were identified. The obtained results were useful in the identification of the colourants from fibres from pre-Columbian Andean textiles extracted with the use of water-methanol solution with formic or hydrochloric acid. The components of each extract were separated on a reversed phase HPLC column and the eluates were monitored at... 

Flaveria haumanii, Cotinus coggygria, Coreopsis spp. and pre Columbian Andean textiles Okanine, luteolin, butein (as aglycones, glycosides or as methyl ethers), quercetin, isorhamnetin (as sulfate esters), sulfuretin, fisetin, hydroxybenzoic acids HCI/Me0H/H20, HCOOH/MeOH A H20 B ACN C H20 with HCOOH 254, 350 nm/ESI (+) Column C4 7... 

The interaction of flavonoids with MDR proteins is of interest not only in the field of cancer prevention and therapy but also in the field of flavonoid bioavailability. Indeed, using specific inhibitors of MDR proteins, it was shown that multiresistant protein 2 (MRP2), but not Pgp, is involved in the efflux of quercetin conjugates from human hepatic cells. Similar observations were made with the cell line Caco-2 (a popular model for human intestinal absorption) where MRP2 was found responsible for the efficient efflux of chrysin after its conjugation into a mixture of glucuronide and sulfate. ... 

Glucoside-3 -sulfate Quercetin 7-methyl ether (rhamnetin) Calorphus elongatus cuhns Restionaceae 367... 

Quercetin 3,7,4 -trrmethyl ether 3-Sulfate and flowers Ipomoea regnelli Convolvulaceae 373... 

Quercetin has been found to inhibit P-gp-mediated efflux of ritonavir in Caco-2 cells (47), to reduce the oxidation of acetaminophen in rat liver microsomes and HepG2 cells (48), and to inhibit the metabolism of midazolam and quinidine in human liver microsomes (49). It did not have an effect on CYP3A4-mediated metabolism and P-gp-mediated transport of saquinavir (41). Rutin was demonstrated to moderately increase the uptake of idar-ubicin in an isolated perfused rat lung model, and also the outflow recovery of the major metabolite idarubicinol, possibly by affecting P-gp (45). Nobe-litin and tangeretin were shown to inhibit OATP-B-mediated uptake of estrone-3-sulfate into human embryonic kidney cells (23). 

Although quercetin may stimulate UGT, it inhibits human hepatic sulfation of resveratrol, acetaminophen, dopamine, (-)-salbutamol, minoxidil, and paracetamol in vitro.69,98-101 This inhibition may be chemopreventive, as activation of some promutagens occurs via SULT reactions.68 However, SULT inhibition may also lead to the accumulation of some xenobiotics and possible toxicity. The magnitude of inhibition by quercetin of SULT appears dependent on the isoform because SULT1A3 is less affected than other isoforms, suggesting a tissue-dependent effect of quercetin.69... 

However, the effect of piperine on SULT and flavonoid status across the life cycle remains to be investigated. Induction of phase II metabolism appears to decrease the bioavailability and accelerate the excretion of flavonoids. For example, Siess et al.115 and Walle et al.116 reported flavones induced rat hepatic UGT activity in HepG2 and Caco-2 cells. This induction of UGT enhanced quercetin glucuronidation in Caco-2 cells. In addition to inducing UGT activity, the flavone chrysin inhibits hepatic SULT-mediated sulfation of acetaminophen and minoxidol." The impact of chrysin on the capacity of COMT action toward flavonoids has not been examined. Further, the effect of age on phase II modulation by piperine and chrysin has not been reported. Thus, information on the relationship between age and intake of flavonoids and other phytochemicals that also affect phase II metabolism is required. 

Vietri M, Vaglini F, Pietrabissa A, et al. Sulfation of R(—)-apomorphine in the human liver and duodenum, and its inhibition by mefenamic acid, salicylic acid and quercetin. Xenobiotica 2002 32(7) 587-594. 

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