Naphthalenyl derivatives for hitting P-gp/MRP1/BCRP transporters

Substituted naphthalenyl derivatives bearing oxazole, or thiazole or furyl heteronuclei have been carried out as bioisosters of aryl-oxazoles and -thiazoles derivatives previously reported in order to investigate the role of the hindrance on the activity towards P-gp/BCRP/and MRP1 transporters. In addition, the role of naphthalenyl group to modulate P-gp intrinsic activity of these compounds was ascertained.The results demonstrated that all naphthalenyl derivatives displayed comparable P-gp activity with respect to lead compounds previously characterized in our SAR studies but were less active towards BCRP and MRP1 pumps. In terms of intrinsic activity, the replacement of aryl with naphthalenyl moiety led to P-gp inhibitors, unambiguous or ambiguous substrates on the base of the heteronucleus and the substituent on the naphthalenyl fragment. Indeed, oxazole derivatives were: inhibitors (R = H, F, OH), unambiguous substrates (R = OCH₃), or ambiguous substrate (R = Br); thiazole derivatives were: unambiguous substrates (R = OCH₃, Br), or ambiguous substrates (R = H, F). Finally furyl derivatives were ambiguous substrates.