Tissue Distribution of Quercetin in Pigs after Long-Term Dietary Supplementation

Abstract

Although the flavonol quercetin is intensively investigated, our knowledge about its bioavailability and possible target organs is far from being complete. The aim of this study was to check the potential of quercetin to accumulate in various tissues after long-term dietary treatment compared with a single treatment with flavonol. Pigs ingested either a single dose of quercetin aglycone (25 mg/kg body weight; Expt. 1) or received the flavonol twice a day at the same dose mixed into their regular meals (i.e 50 mg.kg(-1).d(-1)) for 4 wk (Expt. 2). In both experiments, we took plasma and tissue samples 90 min after the final meal and analyzed them using HPLC. Additionally, the specific activity of the enzyme beta-glucuronidase was measured in selected tissues. Higher flavonol concentrations than in plasma were found in only the liver (Expt. 1) or the intestinal wall and kidneys (Expt. 2). All tissues except blood plasma contained a variable amount of deconjugated quercetin in the range of 30-100% of total flavonols. However, the specific beta-glucuronidase activity was not correlated with the proportions of deconjugated flavonols in the various tissues. Long-term dietary intake of the flavonol did not lead to a greater accumulation in any tissue compared with the single treatment. Flavonol concentrations only exceeded the plasma concentration within organs involved in its metabolism and excretion, including liver, small intestine, and kidneys.

The effect of grain polyphenols and the addition of vitamin E to diets enriched with α-linolenic acid on the antioxidant status of pigs

“…None of the investigated extracts increased the concentrations of total phenols in the muscle, and therefore meat from pigs fed flavonoids and phenolic-enriched diets had similar TBARS values as meat from pigs fed a control diet, but significantly higher than meat from pigs fed α-tocopherol-enriched diets. Very low concentration of quercetin in the LD muscle of pigs was also reported by Bieger et al (2008) who did not observe any direct antioxidant effect of flavonols in meat, relevant for post-mortem storage and stability. The largest amounts of quercetin were noted in the organs involved in metabolism, and quercetin concentration was higher in the blood plasma than in the LD muscle.…”

Effects of Opuntia humifusa Supplementation on Lipid Peroxidation and SOD Protein Expression in the Liver, Kidney, and Skeletal Muscle of Rats Fed a High-fat Diet

“…In fact, quercetin has a powerful antioxidative capacity. tissues even though oral supplemented in rats or pigs [3,7].…”

Polyphenols as Adaptogens – The Real Mechanism of the Antioxidant Effect?

“…Polyphenol feeding studies on pigs have found polyphenols at micromolar concentrations in a variety of tissues and organs (Bieger et al, 2008;Kalt et al, 2008;Kalt et al, 2007), but one concern with these studies is that entrained blood may not have been completely removed, thus casting doubt on the actual concentrations in the tissues. On balance, it seems probable that polyphenols can access tissues and therefore cells in vivo, but probably in the form of conjugated metabolites or breakdown products, rather than the unconjugated forms tested in vitro.…”