摘要：The role of glucose transporters in the transport of flavonoids remains ambiguous. In this study, we examined whether quercetrin would be uptaken and transported intactly in modeled Caco-2 cells, as well as to determine the involvements of sodium-dependent glucose transporter 1 (SGLT1) and glucose transporter 2 (GLUT2) in its transmembrane transport. The uptake experiment was conducted in Caco-2 cells 24 hours after seeded and the transport experiment was conducted in Caco-2 cells after 21 days of culturing in a Millicell system. Quercetrin was administered at 3, 9 or 18 µg/mL; and the timepoints of sampling were 30, 60, 90, 120, and 150 min. In the uptake experiment, the highest intracellular quercetrin concentration was observed in the cells treated with 18 µg/mL quercetrin at 60 min, with a bell-shaped kinetic curve. Quercetin, isorhamnetin, and tamarixetin were detected inside the cells, particularly when treated with the high dose. In the transport experiment, quercetrin was transported from the apical to basolateral side and vice versa; its concentrations depended on dose, time, and transport direction. Only trace amounts of isorhamnetin and tamarixetin were detected in the apical chamber when quercetrin was added to the basolateral chamber. Phloridzin and phloretin, a potent inhibitor of SGLT1 and GLUT2, respectively, significantly diminished quercetrin transport from the apical to basolateral side; and phloretin had a larger inhibitory effect than phloridzin. In conclusion, our results demonstrate that quercetrin is absorbed intactly and then effluxed out of Caco-2 cells through both apical and basolateral membranes probably via SGLT1 and GLUT2.
关键词：absorption; Caco-2 cell monolayer; flavonoid; phloridzin; phloretin; transmembrane transport
