Thieno[2,3-b]pyridines-A new class of multidrug resistance (MDR) modulators

To identify new potent multidrug resistance modulators, we have synthesized a series of novel thieno[ 2,3-b]pyridines and furo[2,3-b] pyridines, and examined their stucture-activity relationships. All synthesized compounds were tested to determine BCRP1, P-gp, and MRP1 inhibitor activity, and most potent MDR modulators were also screened for their toxicity, cytotoxicity and Ca2+ channel antagonist activity. Among these compounds, thieno[2,3-b] pyridine (6r) was found to exhibit a potent P-gp inhibitory action with EC50 = 0.3 +/- 0.2 mu M, MRP1 inhibitory action with EC50 = 1.1 +/- 0.1 mu M and BCRP1 inhibitory action with EC50 = 0.2 +/- 0.05 mu M and may represent suitable candidate for further pharmacological studies. (C) 2014 Elsevier Ltd. All rights reserved.