Halogenated chalcones with high-affinity binding to P-glycoprotein: potential modulators of multidrug resistance.

Previous studies have shown that flavonoids are modulators of the transmembrane P-glycoprotein (P-gp) which mediates cell multidrug resistance. Some structural elements have been identified which seem to contribute to these compounds' activity. In the present study, a series of halogenated chalcones was prepared to further explore the structural requirements for the P-gp modulation. Four halogenated chalcones have been synthesized and evaluated as potential modulators of P-gp-mediated multidrug resistance of cancer cells by in vitro assays using a purified recombinant domain of the transporter containing the modulator binding site. Halogenated chalcones exhibited high-affinity binding, the 2',4', 6'-trihydroxy-4-iodochalcone behaving as the most potent compound with a KD value in the nanomolar range.