Bioavailability of rutin and quercetin in rats

Abstract

Quercetin is a powerful antioxidant which is widely distributed in edible plants, mainly as glycosides such as rutin. It has been reported to be absorbed in mammals, but its metabolism needs further investigation to evaluate its possible physiological effects. We compared the evolution of the absorption of quercetin and rutin in rats fed with supplemented diets. Rutin was absorbed more slowly than quercetin because it must be hydrolysed by the cecal microflora, whereas quercetin was absorbed from the small intestine. Conjugated derivatives of quercetin, and its methylated forms isorhamnetin and tamarixetin, were recovered in plasma from rats receiving the two kinds of experimental diets after the first meal, but after 10 days, no traces of tamarixetin were detected anymore. The rate of elimination of quercetin metabolites seems very low, and high plasma concentrations are easily maintained with a regular supply of quercetin or rutin in the diet.

Characterisation of metabolites of the putative cancer chemopreventive agent quercetin and their effect on cyclo-oxygenase activity

“…Only one methylated species, isorhamnetin (3 0 -O-methyl quercetin), was identified here, while its 4 0 -isomer, tamarixetin, was not. Tamarixetin was found previously in the plasma of rats, but only when they had received a flavonol-free diet prior to quercetin (Manach et al, 1997), which is consistent with its absence in the plasma of the rats studied here. Prior to our study, conjugates of quercetin had not been described in humans following the i.v.…”

“…The pattern of conjugates generated in the rat as established here via scrupulous metabolite characterisation by MS is in broad agreement with previous reports in the literature on the biotransformation of quercetin after oral administration either as dietary glycoside or genuine aglycone (Ueno et al, 1983;Manach et al, 1997;Piskula and Terao, 1998). Only one methylated species, isorhamnetin (3 0 -O-methyl quercetin), was identified here, while its 4 0 -isomer, tamarixetin, was not.…”

“…Most importantly, quercetin has been shown to undergo conjugation with glucuronide and sulphate at one or more of the five hydroxyl moieties of the flavone molecule and methylation at positions 3 0 or 4 0 , thus generating isorhamnetin (3 0 -O-methylquercetin) and tamarixetin (4 0 -O-methylquercetin). These conjugates have been characterised in rat urine, bile and plasma (Ueno et al, 1983;Manach et al, 1997;Piskula and Terao, 1998). A quercetin sulphate and two quercetin sulphate-glucuronides were also found in the perfused rat liver (Shali et al, 1991).…”

Bioavailability in humans of the flavanones hesperidin and narirutin after the ingestion of two doses of orange juice

“…Each line corresponds to one subject. Bioavailability of flavanones in humans C Manach et al Manach et al, 1997). In humans, some enzymatic activities or transport systems facilitate the absorption of glucosylated quercetin in the small intestine, but seem ineffective for flavonoids linked to a rutinose (Hollman et al, 1999;Erlund et al, 2000;Graëfe et al, 2001).…”

Comparative inhibitory potential of selected dietary bioactive polyphenols, phytosterols on CYP3A4 and CYP2D6 with fluorometric high-throughput screening

“…Depending on dietary habits or countries, the daily intake has been estimated between 3 and 70 mg, essentially quercetin (Manach et al 1997). QU and RU are also ingredients in large number of multivitamin and herbal remedies because of its medicinal properties (Erlund et al 2000).…”