Structure-activity studies of substituted quinoxalinones as multiple-drug-resistance antagonists

D. S. Lawrence, J. E. Copper, C. D. Smith

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158 Scopus citations


A significant problem in the clinical treatment of cancer relates to the development of tumor resistance to many chemotherapeutic agents. Acquired drug resistance is often mediated through overexpression of membrane transport proteins that effectively efflux anticancer agents. Two of the best-studied transporters, P-glycoprotein (Pgp) and MRP1, have pharmacological properties that only partially overlap. In our search for improved drug-resistance antagonists, we have identified a family of substituted quinoxalines that selectively antagonizes Pgp over MRP1. Consequently, a focused library of congeners was designed and synthesized starting with a parent bromomethylquinoxalinone. This parent quinoxalinone was then condensed with a series of phenols to yield a family of substituted phenoxymethylquinoxalinones. These compounds were evaluated for their toxicity toward drug-sensitive MCF-7 breast carcinoma cells and for their abilities to antagonize Pgp and MRP1 in drug-resistant cell lines (NCI/ADR and MCF-7/VP, respectively). The results of this structure-activity study indicate that compounds with carbonyl substitutions of the phenoxy group (ester, amide, or ketone moieties) demonstrate excellent antagonism of Pgp while having relatively low toxicity toward drug-sensitive cells. Importantly, none of these compounds antagonized MRP1. Because of their transporter selectivity, we predict that substituted quinoxalinones may be more effective MDR modulators in vivo than are nonselective transporter antagonists.

Original languageEnglish (US)
Pages (from-to)594-601
Number of pages8
JournalJournal of Medicinal Chemistry
Issue number4
StatePublished - Feb 15 2001

All Science Journal Classification (ASJC) codes

  • Molecular Medicine
  • Drug Discovery


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