tamarixetin and Inflammation

Epidemiologic evidence supports that dietary quercetin reduces cardiovascular disease (CVD) risk, but its oral bioavailability is paradoxically low. The aim of this study was to determine whether dietary fat would improve quercetin bioavailability in adults at high risk for CVD and to assess lipid-mediated micellarization of quercetin in vitro.. In a randomized, cross-over study, overweight/obese men and postmenopausal women (n = 4 M/5 F; 55.9 ± 2.1 years; 30.8 ± 1.4 kg/m(2) ) ingested 1095 mg of quercetin aglycone with a standardized breakfast that was fat-free (<0.5 g), low-fat (4.0 g), or high-fat (15.4 g). Plasma was obtained at timed intervals for 24 h to measure quercetin and its methylated metabolites isorhamnetin and tamarixetin. Compared to the fat-free trial, plasma quercetin maximum concentration (Cmax ), and area under curve (AUC0-24 h ) increased (p < 0.05) by 45 and 32%, respectively, during the high-fat trial. During the high-fat trial, isorhamnetin Cmax and AUC0-24 h also increased by 40 and 19%, respectively, whereas Cmax and AUC0-24 h of tamarixetin increased by 46 and 43%, respectively. Dietary fat dose-dependently increased micellarization efficiency of quercetin aglycone in vitro.. Dietary fat improves quercetin bioavailability by increasing its absorption, likely by enhancing its micellarization at the small intestine.

Topics: Area Under Curve; Biological Availability; Biomarkers; Body Mass Index; Chromatography, High Pressure Liquid; Cross-Over Studies; Dietary Fats; Disaccharides; Female; Humans; Inflammation; Linear Models; Male; Middle Aged; Overweight; Oxidative Stress; Quercetin

Our aim was to investigate the effects of an oral supplementation of quercetin at 3 different doses on plasma concentrations of quercetin, parameters of oxidant/antioxidant status, inflammation, and metabolism. To this end, 35 healthy volunteers were randomly assigned to take 50, 100, or 150 mg/d (group Q50-Q150) quercetin for 2 wk. Fasting blood samples were collected at the beginning and end of the supplementation period. Compared with baseline, quercetin supplementation significantly increased plasma concentrations of quercetin by 178% (Q50), 359% (Q100), and 570% (Q150; P < 0.01 for all). High interindividual variation was found for plasma quercetin concentrations (36-57%). Quercetin did not affect concentrations of serum uric acid or plasma alpha- and gamma-tocopherols, oxidized LDL, and tumor necrosis factor-alpha, or plasma antioxidative capacity as assessed by the ferric-reducing antioxidant potential and oxygen radical absorbance capacity assays. In addition, serum lipids and lipoproteins, body composition, and resting energy expenditure did not significantly change during quercetin supplementation. Pharmacokinetics of quercetin were investigated in a subgroup of 15 volunteers. The areas under the plasma concentration-time curves ranged from 76.1 mumol.min.L(-1) to 305.8 mumol.min.L(-1) (50- and 150-mg dosages, respectively). Median maximum plasma concentrations of quercetin (431 nmol/L) were observed 360 min after intake of 150 mg quercetin. In conclusion, daily supplementation of healthy humans with graded concentrations of quercetin for 2 wk dose-dependently increased plasma quercetin concentrations but did not affect antioxidant status, oxidized LDL, inflammation, or metabolism.

Topics: Administration, Oral; Adult; Antioxidants; Dietary Supplements; Disaccharides; Dose-Response Relationship, Drug; Double-Blind Method; Energy Metabolism; Female; Flavonols; Humans; Inflammation; Male; Nutritional Physiological Phenomena; Oxidative Stress; Quercetin

Sepsis is a systemic inflammatory response to pathogenic infection that currently has no specific pharmaceutical interventions. Instead, antibiotics administration is considered the best available option, despite increasing drug resistance. Alternative strategies are therefore urgently required to prevent sepsis and strengthen the host immune system. One such option is tamarixetin (4'- O-methylquercetin), a naturally occurring flavonoid derivative of quercetin that protects against inflammation. The purpose of this study was to determine whether the anti-inflammatory effects of tamarixetin protect against the specific inflammatory conditions induced in lipopolysaccharide (LPS) or Escherichia coli K1 models of sepsis. Our study showed that tamarixetin reduced the secretion of various inflammatory cytokines by dendritic cells after activation with LPS. It also promoted the secretion of the anti-inflammatory cytokine interleukin (IL)-10 and specifically increased the population of IL-10-secreting immune cells in LPS-activated splenocytes. Tamarixetin showed general anti-inflammatory effects in mouse models of bacterial sepsis and decreased bacteria abundance and endotoxin levels. We therefore conclude that tamarixetin has superior anti-inflammatory properties than quercetin during bacterial sepsis. This effect is associated with an increased population of IL-10-secreting immune cells and suggests that tamarixetin could serve as a specific pharmaceutical option to prevent bacterial sepsis.

Topics: Animals; Anti-Inflammatory Agents; Cytokines; Dendritic Cells; Disaccharides; Escherichia coli; Female; Inflammation; Interleukin-10; Lipopolysaccharides; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Quercetin; Sepsis