PAPER

Continuing our studies on the mechanisms underlying the cytotoxicity of potential drugs, we have described several aspects of the in vitro anticancer activity of ruthenium(II) and platinum(II) complexes with bioactive, synthetic aminoflavone ligands. We examined the mechanism of proapoptotic activity of cis-dichlorobis(3-imino-2-methoxyflavanone)ruthenium(II), cis-dichlorobis(3-imino-2-ethoxyflavanone)ruthenium(II), and trans-dichlorobis(3-aminoflavone)platinum(II). Cisplatin was used as a reference compound. The cytotoxicity was investigated by MTT assay. The mechanism of proapoptotic activity of the tested compounds was investigated by evaluation of caspase-8 activity, cytometric analysis of annexin-V positive cells, and mitochondrial potential loss measurement. The results showed that ruthenium compounds break partially or completely the cisplatin resistance by activating the caspase 8-dependent apoptosis pathway and loss of mitochondrial membrane potential. Platinum compounds also have a cytostatic effect, but their action requires more exposure time. Potential mechanisms underlying drug resistance in the two pairs of cancer cell lines were investigated: total glutathione content, P-glycoprotein activity, and differences in the activity of DNA repair induced by nucleotide excision. Results showed that cisplatin-resistant cells have elevated glutathione levels relative to sensitive cells. Moreover, they indicated the mechanisms enabling cells to avoid apoptosis caused by DNA damage. Pg-P activity has no effect on the development of cisplatin resistance in the cell lines described.

Objectives: Cisplatin is a classical anticancer drug used in the treatment of ovarian cancer. Unfortunately, the treatment is associated with numerous adverse effects. Studies concerning new platinum derivatives with less organ toxicity are conducted. The aim of this study was to analyse the effect of a new trans-platinum(II) complex of 3-aminoflavone on the viability and mortality of the cells from OVCAR 3 and CAOV 3 ovarian cancer cell lines and on the expression of the selected genes involved in the process of apoptosis. Material and methods:The viability of ovarian cancer cells and the cytotoxicity of a trans-platinum(II) complex of 3-aminoflavone: [trans-Pt(3-af ) 2 Cl 2 ), trans-bis-(3-aminoflavone) dichloridoplatinum(II)] and cisplatin were analysed using a spectrophotometric method with the use of MTT assay and LDH assay. BAX, BCL2, BIRC5 gene expression analysis on mRNA level was conducted with the use of Real-Time PCR method.Results: It was observed that parallel to an increase in the concentration of the new complex compound and cisplatin there is a decrease in viability and an increase in mortality of ovarian cancer cells. As a result of exposure to the studied compound and cisplatin, an increased BAX gene expression and decreased BCL2 and BIRC5 gene expression were observed in the studied ovarian cancer cell lines. Conclusion:Trans-Pt(3-af ) 2 Cl 2 exhibits anticancer activity towards OVCAR 3 and CAOV 3 ovarian cancer cell lines. The studied complex compound can be considered as a potential anticancer drug.

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Following previous studies devoted to trans-Pt(3-af) 2 Cl 2 , in this paper, the molecular structure and intermolecular interactions of the title complex are compared with other cisplatin analogues of which the crystal structures are presented in the Cambridge Structural Database (CSD). Molecular Hirshfeld surface analysis and computational methods were used to examine a possible relationship between the structure and anticancer activity of trans-Pt(3-af) 2 Cl 2 . The purpose of the article was also to investigate the effect of hyperthermia on the anticancer activity of cisplatin, cytostatics used in the treatment of patients with ovarian cancer and a new analogue of cisplatin-trans-Pt(3-af) 2 Cl 2 . The study was conducted on two cell lines of ovarian cancer sensitive to Caov-3 cytostatics and the OVCAR-3 resistant cisplatin line. The study used the MTT (3-(4,5-dimethylthiazol-2,5-diphenyltetrazolium bromide) cell viability assay, LDH (lactate dehydrogenase), and the quantitative evaluation method for measuring gene expression, i.e., qPCR with TagMan probes. Reduced survivability of OVCAR-3 and Caov-3 cells exposed to cytostatics at elevated temperatures (37 • C, 40 • C, 43 • C) was observed. Hyperthermia may increase the sensitivity of cells to platinum-based antineoplastic drugs and paclitaxel, which may be associated with the reduction of gene expression related to apoptotic processes.

This work presents the synthesis, spectroscopic properties and single-crystal X-ray examination of the structure of 3-hydroxyiminoflavanone and its palladium complex. It presents the results of NMR (Nuclear Magnetic Resonance) spectroscopy, electron-density studies based on X-ray wavefunction refinement and theoretical calculations combined with QTAIM (Quantum Theory of Atoms in Molecules) and ELI-D (Electron Localizability Indicator) analyses. These offer an interesting new insight into the structures and behavior of flavanone and its complex, in solid state and in solution. The study also examines the cytotoxicity of the ligand and its complex against three human ovarian and lung cancer cell lines.

The crystal structure of the new polymorphic form of 3-aminoflavone (3-AF) has been determined by single crystal X-ray diffraction. This report presents results of fluorimetric studies on 3-AF in methanol and aquatic solvents. Based on 3D fluorescence emission spectra, optimal values for excitation (λex) and emission/analytical (λem) wavelength, the analytical concentration range as well as the range of concentration quenching for the studied compound were established. Moreover, the limit of detection (LOD) and the limit of quantification (LOQ) were determined. The results were compared with those obtained using the standard UV-Vis absorption spectrophotometric method. The effect of acidity (pH) and the concentration of halide anions (chlorides, bromides, iodides and fluorides) on fluorescence quenching were analysed.

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