Effect of quercetin on the transport of N-acetyl 5-aminosalicylic acid

Objectives The aim of this study was to investigate the transporter‐mediated transport of N‐acetyl 5‐aminosalicylic acid (Ac‐5‐ASA) and the effect of quercetin on Ac‐5‐ASA transport. Methods Caco‐2 cell monolayers grown in Transwells were used to study the transport of Ac‐5‐ASA in the absence or presence of quercetin, and apical‐to‐basolateral and basolateral‐to‐apical apparent permeability (PappAB and PappBA values, respectively) was determined. The effect of transporter inhibitors, such as MK571, quinidine and mitoxantrone, on the transport of Ac‐5‐ASA was investigated. Key findings In the absence of transporter mediators, the transport of Ac‐5‐ASA was much higher in the basolateral‐to‐apical direction than in the opposite direction. The PappBA/PappAB ratio of Ac‐5‐ASA was 4.89. Quercetin inhibited the apical efflux of Ac‐5‐ASA and decreased the PappBA/PappAB ratio to 1.05. Of the transporter inhibitors, MK571 decreased the PappBA/PappAB ratio to 1.07; however, neither quinidine nor mitoxantrone had an effect on Ac‐5‐ASA transport. Conclusions Ac‐5‐ASA was excreted by multidrug resistance‐associated protein 2 from Caco‐2 cells, and its transport was inhibited by quercetin. Our findings suggest that dose levels of sulfasalazine or 5‐aminosalicylic acid can be decreased by coadministration of quercetin, leading to improved pharmaceutical care for inflammatory bowel diseases.