ABSTRACT
Chronic ingestion of apple pectin has been shown to increase the absorption of quercetin in rats. The present study was designed to elucidate whether the simultaneous ingestion of quercetin with apple pectin could enhance the absorption of quercetin in humans, and the effects of dose dependency and degree of pectin methylation on quercetin absorption were also investigated. Healthy volunteers (n 19) received 200 ml of 0.5 mg/ml of quercetin drinks with or without 10 mg/ml of pectin each in a randomised cross-over design study with over 1-week intervals; urine samples from all the subjects were collected within 24 h after ingestion of the test drinks, and urinary deconjugated quercetin and its metabolites were determined using HPLC. The sum of urinary quercetin and its metabolites excreted was increased by 2.5-fold by the simultaneous ingestion of pectin. The metabolism of methylated quercetin (isorhamnetin and tamarixetin) was not affected by pectin ingestion. In six volunteers, who received quercetin drinks containing 0, 3 and 10 mg/ml of pectin, the sum of urinary quercetin and its metabolites excreted also increased in a pectin dose-dependent manner. Furthermore, the simultaneous ingestion of quercetin with low-methoxy and high-methoxy pectin, respectively, increased the sum of urinary excretion of quercetin and its metabolites by 1.69-fold and significantly by 2.13-fold compared with the ingestion of quercetin without pectin. These results elucidated that apple pectin immediately enhanced quercetin absorption in human subjects, and that its enhancing effect was dependent on the dose and degree of pectin methylation. The results also suggested that the viscosity of pectin may play a role in the enhancement of quercetin absorption.
Subject(s)
Antioxidants/metabolism , Dietary Supplements , Gastrointestinal Agents/administration & dosage , Intestinal Absorption , Pectins/administration & dosage , Quercetin/metabolism , Up-Regulation , Adult , Antioxidants/analysis , Beverages , Cross-Over Studies , Disaccharides/metabolism , Disaccharides/urine , Fruit/chemistry , Gastrointestinal Agents/chemistry , Gastrointestinal Agents/metabolism , Humans , Hydrolysis , Male , Malus/chemistry , Methylation , Pectins/chemistry , Pectins/metabolism , Quercetin/analogs & derivatives , Quercetin/urine , Renal Elimination , ViscosityABSTRACT
This present work describes an effective new method for study traditional Chinese medicine (TCM) on meridian tropism (MT) theory, which plays an essential role in clinical selection of TCM according to syndromes and strengthens the therapeutic effects. The new thread included material basis foundation and its tissue distribution study. Xiheliu, the most popular TCM on heart tropism, was investigated by simple and accurate high performance liquid chromatography (HPLC) method. The analysis of plasma after oral administration the total flavonoid of Xiheliu (TFX) exhibited that tamarixetin and kaempferide had the highest concentration and approximately the highest level within 25 min. The mixture of them could last accelerating the urine excretion more than 7 h after a single dose and could not cause the disorder of ion in rats, which was observed in diuretic activity experiment. In view of the reported biological activities was consistent with the effects of Xiheliu, tamarixetin and kaempferide were likely to be the material basis of it. Tissue distribution study showed that the highest level of analytes was in heart, lung, kidney and liver, and most tissues reached maximum level at 30 min post-dose. Since liver was the most important blood-supply tissue, the result of this experiment was in accordance with the MT record of Xiheliu and confirmed that tamarixetin and kaempferide was the material bases of it on MT. This is the first report for the illumination of material basis and the mechanism of Xiheliu on MT by analysis the record of Xiheliu in Compendium of Materia Medica and experimental study.