Antifungal and antiaflatoxigenic assessment of new Cu(II)-pq complexes against Aspergillus parasiticus, in dark conditions and under visible irradiation.

The issue of food contamination by fungi and aflatoxins; constitutes a serious concern not only for human/animal health but also for agriculture and the economy. Aflatoxins are secondary metabolites produced by certain filamentous fungi and contaminate a variety of foodstuffs. In this context, control of fungal growth and aflatoxin contamination appears to be important. The present study aimed to investigate new Cu(I) and Cu(II)-quinoxaline complexes, namely [Cu(2,2´-pq)(NO3)](NO3) (1), [Cu(2,2´-pq)2(NO3)](NO3)·6H2O (2) and [Cu(2,2΄-pq)2](BF4) (3), where 2,2´-pq is 2-(2'-pyridyl quinoxaline), as antifungal agents against Aspergillus parasiticus. All complexes, the ligand and the starting material Cu(NO3)2-3H2O, regardless of the concentration used, caused inhibition of A. parasiticus growth ranged from 8.52 to 33.33%. The fungal growth inhibition was triggered when irradiation in visible (λ > 400 nm) was continuously applied (range 18.36-57.20%). The highest inhibitory activity was exhibited by the complex [Cu(2,2´-pq)2(NO3)](NO3)·6H2O and for this reason, it was selected to be studied for its ability to suppress aflatoxin B1 produced by A. parasiticus. AFB1 production after the irradiation process was found to be suppressed by 25% compared to AFB1 produced in dark conditions.

Synthesis, characterization, DNA binding and cytotoxicity studies of two novel Cu(II)-2-(2'-pyridyl) quinoxaline complexes.

Two novel copper (II) complexes, namely [Cu(2,2'-pq)(NO3)](NO3) (1) and [Cu(2,2'-pq)2(NO3)](NO3)·6H2O(2) where 2,2'-pq is 2-(2'-pyridyl quinoxaline) were synthesized and characterized by various spectral methods. Complex 2 characterized by single crystal X-ray diffraction showed a distorted trigonal bipyramidal geometry and crystallized together with an hexamer, (H2O)6 cluster, with R66(12) topology and chair conformation. The interaction of Calf Thymus DNA (CT-DNA) with 1 and 2 was investigated by UV-Visible absorption spectra, Viscosity, Cyclic Voltammetry, Fluorescence and Circular Dichroism (CD), indicating that both complexes can bind to DNA both by means of intercalation and groove binding. Their DNA interaction mode depends on their concentrations and the differences between their structures. Cleavage experiments were performed by agarose gel electrophoresis using pBR322 DNA both in dark and after illumination. Furthermore, the cytotoxicity of both complexes was evaluated against MCF-7 and healthy cells (HEK-293) by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays; moreover their cell uptake against MCF-7 tumor cells and HEK-293 normal cells was revealed by using confocal laser scanning. Both complexes have the potential to act as effective anticancer drugs with 2 to present an IC50 smaller than that of cis-platin and also to be useful for optically probing tumor cells since it fluoresces at blue and green when is treated with MCF-7 cells.