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We report the synthesis and characterization of three new complexes of the natural flavonoid 5-hydroxyflavone (primuletin) and Al (III), Ga (III), In (III), respectively. The physico-chemical properties and structural features of these three novel compounds have been investigated by elemental and thermogravimetric analysis, molar conductance and several spectroscopic techniques, including FT-IR, UV-Vis and mass spectra. Based on the experimental data, the general chemical formula of the complexes iswhere M is the cation and n = 2 for Al (III), n = 0 for Ga (III), n = 1, for In (III); each one of the three 5-hydoxyflavone molecules acts as a monoanionic bidentate chelate ligand in the complexes. DFT calculations further sustain the proposed structures of the complexes. Cytotoxicity was studied using MTS assay on cervical, breast, colon and ovary adenocarcinoma cell lines.The central metal ions exert cytotoxic effects in a disparate manner: Al (III) enhances, while Ga (III) and In (III) decrease the cytotoxicity of the ligand.As a means to investigate the mechanism underlying the cytotoxic effects of the complexes, interactions with calf thymus DNA, human serum albumin and transferrin were also carried out.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Protectin (CD59), a glycosylphosphatidylinositol-anchored cell membrane glycoprotein, is differentially expressed on melanocytic cells and represents the main restriction factor of C-mediated lysis of melanoma cells. In this study, we report that CD59-positive melanoma cells constitutively release a soluble form of CD59 (

Immunohistochemical and/or indirect immunofluorescence analysis with monoclonal antibody (MAb) H19 demonstrated the expression of protectin (CD59) in 54 surgically removed metastatic melanoma lesions and on 8 out of 12 melanoma cell lines. CD59 expression had a low degree of intra- and intertumor heterogeneity. SDS-PAGE analysis showed that the molecular weight of CD59 expressed on melanoma cells is about 20 kDa. Treatment of melanoma cells with 5U/ml of phosphatidylinositol-specific phospholipase C completely abolished cell-surface expression of CD59. Interferon-gamma and/or tumor necrosis factor-alpha or phorbol 12-myristate 13-acetate neither modulated the expression of CD59 by melanoma cells nor influenced the amounts of CD59-specific mRNA. F(ab')2 fragments of anti-CD59 MAb YTH53. I did not inhibit the lysis of melanoma cells by allogeneic natural killer (NK) cells or lymphokine-activated killer (LAK) cells. In contrast, the whole Ig molecule of MAb HI9 or YTH53.I significantly (p < 0.05) enhanced NK-cell-mediated lysis of melanoma cells, suggesting the induction of antibody-dependent cell-mediated cytotoxicity. Lastly, masking of CD59 by MAb YTH53.I or its F(ab')2 fragments significantly (p < 0.05) enhanced, in a dose-dependent fashion, the lysis of anti-GD3-sensitized melanoma cells by homologous complement. These data demonstrate that CD59 expressed by human melanoma cells might regulate host-tumor interaction by protecting neoplastic cells from complement-mediated lysis.