Bioavailability of dietary isoquercitrin-γ-cyclodextrin molecular inclusion complex in Sprague–Dawley rats and healthy humans

Abstract

Isoquercitrin has been drawing increasing commercial concern since it has better bioavailability than quercetin and displays a wide range of in-vivo and in-vitro pharmacological effects. The main objective of the present study was to evaluate the pharmacokinetics of the IQC-γCD inclusion complex in Sprague-Dawley (SD) rats and in a controlled non-randomized, double-blind, and crossover study among the healthy volunteers. For instance, in SD rats administrated with IQC-γCD formulation by oral gavage feeding (0.05 mM/Kg body weight) showed significantly higher bioavailability (P < 0.001) of the quercetin and its metabolites compared to quercetin (control) intake. Whereas, in healthy humans (n = 8) an acute administration of IQC-γCD molecular inclusion complex (0.47 mM; the doses corresponds to 2.34 mg quercetin equivalence/Kg body weight) significantly enhanced the plasma conjugated quercetin and its metabolites concentration (P < 0.0001), and exhibited a greater pharmacokinetic profile compared to quercetin embedded in dextrin (control) supplementation. The results indicate an improved bioavailability of quercetin and its metabolites of IQC-γCD inclusion complex compared to respective controls in both animals and humans, wherein intestinal epithelial enzyme lactase-phlorizin hydrolase preferably hydrolyze the isoquercitrin of IQC-γCD inclusion complex to conjugated quercetin and its glucuronides and/or sulfates metabolites. The results also support the useful future applications of IQC-γCD inclusion complex in food additives, health supplements, and functional beverages for health benefits.