3-methylquercetin and Cardiovascular-Diseases

Epidemiological studies indicate beneficial effects of flavonoids on cardiovascular disease (CVD) risk.. To study the effect of flavonoid-rich sea buckthorn berry (SBB) on circulating lipid markers associated with CVD risk and plasma flavonol concentration. Also investigated was whether changes in the circulating flavonol concentrations correlate with the SBB induced changes in C-reactive protein (CRP) concentration observed previously.. In all 229 healthy participants completed the randomized double-blind study and consumed daily 28 g of SBB or placebo for 3 months. Fasting blood samples for the analysis of lipid markers and flavonols were obtained at the beginning and end of the study.. Compared to the placebo, the consumption of SBB increased the plasma concentration of the flavonols quercetin and isorhamnetin significantly [treatment differences 3.0 ng/ml (P = 0.03) and 3.9 ng/ml (P < 0.01), respectively]. The increase of kaempferol concentration was not significant [treatment difference 0.7 ng/ml (P = 0.08)]. SBB did not affect the serum total, HDL, LDL cholesterol, or the serum triacylglycerol concentrations. There was no correlation between the changes in flavonol and CRP concentrations of participants.. The consumption of SBB significantly increased the fasting plasma concentration of quercetin and isorhamnetin indicating that it is a good dietary source of flavonols. However, this did not convert to affecting the circulating concentrations of lipid markers in healthy, normolipidemic adults having healthy diets.

Topics: Adult; C-Reactive Protein; Cardiovascular Diseases; Cholesterol; Dose-Response Relationship, Drug; Double-Blind Method; Female; Flavonols; Fruit; Hippophae; Humans; Male; Middle Aged; Quercetin; Triglycerides; Young Adult

Sea buckthorn (Hippophaë rhamnoides L.) is a rich source of flavonols, especially isorhamnetin. Most prospective cohort studies have indicated some degree of inverse association between flavonoid intake and coronary heart disease. Animal and human studies suggest that sea buckthorn flavonoids may scavenge free radicals, lower blood viscosity, and enhance cardiac function. The effects of flavonol aglycones derived from sea buckthorn on the risk factors of cardiovascular disease as well as their absorption were studied in humans. The flavonols, ingested with oatmeal porridge, did not have a significant effect on the levels of oxidized low-density lipoprotein, C-reactive protein, and homocysteine, on the plasma antioxidant potential, or on the paraoxonase activity. Flavonols at two dosages in oatmeal porridge were rapidly absorbed, and a relatively small amount of sea buckthorn oil added to the porridge seemed to have increased the bioavailability of sea buckthorn flavonols consumed at the higher dose.

Topics: Adult; Antioxidants; Aryldialkylphosphatase; Avena; C-Reactive Protein; Cardiovascular Diseases; Chromatography, High Pressure Liquid; Diet; Double-Blind Method; Flavonols; Hippophae; Homocysteine; Humans; Intestinal Absorption; Lipoproteins, LDL; Male; Middle Aged; Placebos; Plant Oils; Quercetin

Quercetin, a flavonoid present in the human diet, which is found in high levels in onions, apples, tea and wine, has been shown previously to inhibit platelet aggregation and signaling in vitro. Consequently, it has been proposed that quercetin may contribute to the protective effects against cardiovascular disease of a diet rich in fruit and vegetables.. A pilot human dietary intervention study was designed to investigate the relationship between the ingestion of dietary quercetin and platelet function.. Human subjects ingested either 150 mg or 300 mg quercetin-4'-O-beta-D-glucoside supplement to determine the systemic availability of quercetin. Platelets were isolated from subjects to analyse collagen-stimulated cell signaling and aggregation.. Plasma quercetin concentrations peaked at 4.66 microm (+/- 0.77) and 9.72 microm (+/- 1.38) 30 min after ingestion of 150-mg and 300-mg doses of quercetin-4'-O-beta-D-glucoside, respectively, demonstrating that quercetin was bioavailable, with plasma concentrations attained in the range known to affect platelet function in vitro. Platelet aggregation was inhibited 30 and 120 min after ingestion of both doses of quercetin-4'-O-beta-D-glucoside. Correspondingly, collagen-stimulated tyrosine phosphorylation of total platelet proteins was inhibited. This was accompanied by reduced tyrosine phosphorylation of the tyrosine kinase Syk and phospholipase Cgamma2, components of the platelet glycoprotein VI collagen receptor signaling pathway.. This study provides new evidence of the relatively high systemic availability of quercetin in the form of quercetin-4'-O-beta-D-glucoside by supplementation, and implicates quercetin as a dietary inhibitor of platelet cell signaling and thrombus formation.

Topics: Blood Platelets; Cardiovascular Diseases; Chromatography, High Pressure Liquid; Collagen; Cross-Over Studies; Dietary Supplements; Dose-Response Relationship, Drug; Female; Flavonols; Glucosides; Humans; Immunoblotting; Male; Phosphorylation; Platelet Activation; Platelet Aggregation; Quercetin; Signal Transduction; Thrombosis; Time Factors; Tyrosine