Description
MK-571 is a selective, orally active CysLT1 receptor (Cysteinyl leukotriene receptor) antagonist. MK571 is a multidrug resistance protein-2 (ABCC2, Mrp2) inhibitor and has been widely used to demonstrate the role of Mrp2 in the cellular efflux of drugs, xenobiotics and their conjugates. The estimated Ki for inhibition of the synthesis of K-4?-O-GlcA by MK571 is 19.7 muM. MK571 dose-dependently inhibits the intracellular biosynthesis of all flavonol glucuronides and sulphates by Caco-2 cells. MK571 significantly inhibits phase-2 conjugation of kaempferol by cell-free extracts of Caco-2, and production of kaempferol-4-O-glucuronide was competitively inhibited. These data show that MK571, in addition to inhibiting MRP2, is a potential inhibitor of enterocyte phase-2 conjugation