Synthesis and In Vitro Evaluation of 8‐Hydroxyquinolines as Dental Plaque Inhibitors

Some 4‐ and 5‐substituted 8‐hydroxyquinolines, with predicted log P values in the range of 1.48–2.90, were synthesized by modified Skraup reactions or thermal cyclization. These hydroxyquinolines include the 5‐methyl, 4, 5‐dimethyl, 4‐methyl, 5‐hydroxy‐4‐methyl, 5‐methoxy, 5‐methoxy‐4‐methyl, 4‐hydroxy, 4‐chloro, 4‐amino, and 5‐amino analogs. Partition coefficients, antibacterial activity, and antiplaque activity were determined. Four analogs showed in vitro antiplaque activity. None of the derivatives with ionizable functions was active.