New copper(II) complexes including pyridine-2,5-dicarboxylic acid: synthesis, spectroscopic, thermal properties, crystal structure and how these complexes interact with purified PON 1 enzyme

Abstract

<p>We report the synthesis of two square-pyramidal copper(II) complexes, [Cu(2,5-pydc)(2-aepy)(H₂O)]·H₂O, <b>1</b>, and [Cu(2,5-pydc)(2-ampy)(H₂O)]·H₂O, <b>2</b> (2-aepy = 2-(aminoethyl)pyridine, 2-ampy = 2-(aminomethyl)pyridine, 2,5-pydc = pyridine-2,5-dicarboxylic acid or isocinchomeronic acid). The synthesized complexes have been characterized by X-ray diffraction, FT-IR, elemental, and thermal analysis techniques. The crystal structure of <b>1</b> was established by X-ray analysis. Powder X-ray diffraction analysis showed that the complexes are pure. The inhibition of human serum paraoxonase 1 (PON 1, EC 3.1.8.1) enzyme with these complexes were investigated. We used diethyl 4-nitrophenyl phosphate as a substrate to measure the paraoxonase activity of PON 1 enzyme spectrophotometrically. Complexes <b>1</b> and <b>2</b> decreased the <i>in vitro</i> PON 1 activity with different inhibition mechanisms. Complexes <b>1</b> and <b>2</b> inhibited paraoxonase activity of this enzyme as competitively and noncompetitively, respectively.</p