Crystal structures and biological evaluation of Cu(II) complexes with 3-ethyl-2-acetylpyrazine N(4)-isopropylthiosemicarbazone

Abstract

Five Cu(II) complexes, [Cu(L)₂]&middot;CH₃OH (<strong>1</strong>), [CuLCl] (<strong>2</strong>), [CuLBr] (<strong>3</strong>), [CuL(NO₃)] (<strong>4</strong>) and [Cu₂(L)₂(SO₄)]&middot;3H₂O&middot;CH₃OH (<strong>5</strong>), based on HL (where HL = 3-ethyl-2-acetylpyrazine N(4)-isopropylthiosemicarbazone) have been synthesized and characterized by X-ray diffraction analyses. The complexes (<strong>1</strong>) and (<strong>2</strong>) are mononuclear, while the other three are binuclear. <em>In vitro </em>experiments carried out to investigate the effect of complexes (<strong>1</strong>-<strong>5</strong>) on human hepatoma cells SMMC-7721, human gastric cancer SGC-7901 and human pancreatic cancer Patu-8988 show that complexes (<strong>1</strong>-<strong>5</strong>) can inhibit the proliferation of all the three cancer cell lines. The inhibition of cell growth is related to increase of tumor cell apoptosis, which is further confirmed by results of western blotting wherein the expression of p53 and Bax increased, and expression of Bcl-2 decreased in complex (<strong>3</strong>) treated SMMC-7721 cells.