Zinc(II) Complexes of Acylpyrazolones Decorated with a Cyclohexyl Group Display Antiproliferative Activity Against Human Breast Cancer Cells

Five- and six-coordinated zinc(II) complexes, [Zn(Q (R))(2)(H2O)] (1-2) and [Zn(Q (R))(2)(L)] (3-8) {HQ (R) = 4-R(C=O)-5-pyrazolones in general, in detail HQ(C17), R = -(CH2)(16)CH3, HQ(Cy), R = -C6H11; L = bipy, tmeda or en} have been synthesized and characterized by IR, H-1 and C-13 NMR, UV/Visible spectroscopy, elemental analysis, TGA and ESI mass spectrometry. The square pyramidal complex [Zn(Q(C17))(2)(H2O)] (1) has been structurally characterized, together with a trans octahedral [Zn(Q(Cy))(2)(EtOH)(2)] (2b) species obtained by recrystallization of [Zn(Q(Cy))(2)(H2O)] (2) from ethanol. Additionally, in both complexes [Zn(Q(Cy))(2)(bipy)] (4) and [Zn(Q(C17))(2)(tmeda)] (5) structurally characterized by single crystal X ray diffraction, the same amount of Delta and ? enantiomers are present, with the only difference related to the mutual disposition of the different type of the Q (R) coordinated oxygen atoms. The cytotoxicity of the complexes [Zn(Q(Cy))(2)(H2O)] (2), [Zn(Q(Cy))(2)(bipy)] (4) and [Zn(Q(Cy))(2)(en)] (8) has been evaluated in vitro against MCF-7 human breast cancer cell line in a biohybrid membrane system. Results revealed that zinc complexes possess antiproliferative activity inducing apoptosis by activation of caspase-3 and p-JNK.