Background and ObjectivesThe importance of quercetin and flavonoids in the diet and as food supplements is well known, and literature studies support their potential use to treat several human diseases. Many beneficial properties have been described for quercetin, so much effort has been directed into overcoming the major drawbacks of this natural compound—its poor solubility and low oral absorption. The aims of this study were to compare a new food-grade lecithin-based formulation of quercetin, Quercetin Phytosome®, to unformulated quercetin in terms of solubility in simulated gastrointestinal fluids and oral absorption in a randomized crossover pharmacokinetic study of healthy volunteers.MethodsThe solubility of the new formulation was determined by in vitro incubation in simulated gastrointestinal fluids, and quercetin was detected by ultra performance liquid chromatography. A single-dose, randomized, six-sequence/three-period crossover clinical trial (3 × 3 × 3 crossover design) with a balanced carryover effect was conducted in healthy volunteers under fasting conditions. Twelve healthy volunteers of both sexes with an age range of 18–50 years were recruited; one dose of quercetin and two different doses of Quercetin Phytosome were administered orally as film-coated tablets. Pharmacokinetic samples were collected at twelve time points (from 0 h to 24 h) after administration, and quercetin levels were measured by HPLC/MS/MS. Data were analyzed using the Phoenix WinNonlin (v.6.4) software package, and the most significant pharmacokinetic parameters were calculated. Statistical analysis involved performing a two-way ANOVA with repeated measures followed by post hoc analysis (Tukey’s test).ResultsSignificant improvements in both in vitro solubility and oral absorption (in terms of both exposure and maximum concentration achieved) by healthy volunteers in a human clinical study were obtained with the Quercetin Phytosome formulation as compared to unformulated quercetin.ConclusionsA more soluble formulation of quercetin based on lecithin, Quercetin Phytosome, has recently been developed, and was found to facilitate the attainment of very high plasma levels of quercetin—up to 20 times more than usually obtained following a dose of quercetin—when the novel formulation was administered orally in human volunteers, and it did not have any notable side effects. These results suggest that Quercetin Phytosome allows the oral administration of quercetin in a safe and bioavailable manner, thus facilitating the effective utilization of this natural compound to treat various human diseases.

Objective: Hyperlipemia represents an independent risk factor in the development of atherosclerosis in patients undergoing type 2 diabetes mellitus (DM). Moreover, the pharmacological treatment of dyslipemia in patients undergoing type 2 DM (e.g. by means of statins), is accompanied by relevant side effects and oral supplementation with natural antioxidants, such as Citrus polyphenols, has recently been suggested to improve cardioprotection in such patients. However, due to the poor gastrointestinal absorption of polyphenols, novel formulations have recently been developed for getting a better bioavailability of polyphenolic rich fractions of citrus species extract rich in polyphenols. Methods: Here, we investigated the effect of standard bergamot polyphenolic fraction (BPF®) as well as of its phytosomal formulation (BPF Phyto), in patients with type 2 DM and hyperlipemia. A randomized, double blind, placebo-controlled study was carried out in 60 patients suffering from type 2 DM and mixed hyperlipemia. </P><P> Patients were divided into three groups: one receiving placebo, the second receiving standard BPF and the third BPF Phyto. Results: In the groups receiving BPF and BPF Phyto, a significant reduction of fasting plasma glucose, serum LDL cholesterol and triglycerides accompanied by increased HDL cholesterol was observed. This effect was associated with significant reduction of small dense atherogenic LDL particles, as detected by means of proton NMR Spectroscopy, thus confirming the hypolipemic and hypoglycemic effect of bergamot extract both when using standard formulation as well as BPF Phyto. No differences were seen in the therapeutic response among groups receiving BPF and BPF Phyto, thus suggesting a substantial bioequivalence in their hypoglycemic and hypolipemic profile. However, when comparing the pharmacokinetic profile of naringin (the major component of BPF) and its metabolites, in patients treated with BPF Phyto, an at least 2,5 fold increase in its absorption was found, confirming in human studies the better profile of BPF Phyto compared to standard BPF. Conclusion: These data suggest that better absorption and tissue distribution of BPF Phyto formulation represents an innovative approach in supplementation treatments of cardiometabolic disorders.

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Zinc deficiency is common in cirrhosis, and was proved to affect nitrogen metabolism. In experimental animals, zinc status may also affect glucose disposal, and acute zinc supplementation improves glucose tolerance in healthy subjects. This study was aimed at measuring the effects of long-term oral zinc supplements on glucose tolerance in cirrhosis. The time courses of glucose, insulin, and C-peptide in response to an intravenous (i.v.) glucose load were analyzed by the minimal-model technique before and after long-term oral zinc supplements (200 mg three times per day for 60 days) in 10 subjects with advanced cirrhosis and impaired glucose tolerance or diabetes. The test was performed using a simplified procedure, based on 20 blood samples collected within 4 hours from the glucose load. Normal values were obtained in 25 age-matched healthy subjects. Zinc levels were low to normal or reduced before treatment, and were normalized by oral zinc. Glucose disappearance improved by greater than 30% in response to treatment. There were no changes in pancreatic insulin secretion and systemic delivery, or in the hepatic extraction of insulin. Insulin sensitivity (SI), which was reduced by 80% before treatment, did not change. Glucose effectiveness (SG) was nearly halved in cirrhosis before treatment (0.013 [SD 0.007] min(-1) v. 0.028 [SD 0.009] in controls; P < .001), and increased to 0.017 (SD 0.009) after zinc (P < .05 v. baseline). The return to normal of plasma zinc levels after long-term zinc treatment in advanced cirrhosis improves glucose tolerance via an increase of the effects of glucose per se on glucose metabolism. Poor zinc status may contribute to the impaired glucose tolerance and diabetes of cirrhosis.

A cytoplasmic antigen associated to inosine-5'-monophosphatedehydrogenase 2 eliciting specific antibodies (antirods and rings, RR) has been identified in patients with chronic hepatitis C who were exposed to pegylated interferon (PI) and ribavirin (RBV). The significance of anti-RR in these patients merits to be investigated. Sera from 88 chronic hepatitis C virus (HCV)-infected patients undergoing PI-RBV therapy were analysed for the presence of RR pattern by indirect immunofluorescence on HEp-2 substrate (Inova Diagnostics, San Diego, CA, USA). Anti-RR antibodies developed de novo in 32 patients independently of any demographic and virological feature, but with a significant association with cumulative exposure to PI-RBV (P = 0.0089; chi-square test). RR pattern was significantly more frequent in relapsers than in patients achieving sustained virological response (56% vs 30%; P = 0.0282, chi-square test). Anti-RR titre ranged from 1:80 to 1:1280, but significantly declined following treatment cessation. Anti-RR develop de novo in a substantial proportion of patients exposed to PI-RBV in relation to the duration of treatment exposure. Further investigations are necessary to unravel the mechanisms leading to the formation of these autoantibodies.

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