Search for new biologically active compounds: in vitro studies of antitumor and antimicrobial activity of dirhodium(II,II) paddlewheel complexes.

Four neutral Rh1-Rh4 complexes of the general formula [Rh2(CH3COO)4L2], where L is an N-alkylimidazole ligand, were synthesized and characterized using various spectroscopic techniques, and in the case of Rh4 the crystal structure was confirmed. Investigation of the interactions of these complexes with HSA by fluorescence spectroscopy revealed that the binding constants Kb are moderately strong (∼104 M-1), and site-marker competition experiments showed that the complexes bind to Heme site III (subdomain IB). Competitive binding studies for CT DNA using EB and HOE showed that the complexes bind to the minor groove, which was also confirmed by viscosity experiments. Molecular docking confirmed the experimental data for HSA and CT DNA. Antimicrobial tests showed that the Rh2-Rh4 complexes exerted a strong inhibitory effect on G+ bacteria B. cereus and G- bacteria V. parahaemolyticus as well as on the yeast C. tropicalis, which showed a higher sensitivity compared to fluconazole. The cytotoxic activity of Rh1-Rh4 complexes tested on three cancer cell lines (HeLa, HCT116 and MDA-MB-231) and on healthy MRC-5 cells showed that all investigated complexes elicited more efficient cytotoxicity on all tested tumor cells than on control cells. Investigation of the mechanism of action revealed that the Rh1-Rh4 complexes inhibit cell proliferation via different mechanisms of action, namely apoptosis (increase in expression of the pro-apoptotic Bax protein and caspase-3 protein in HeLa and HCT116 cells; changes in mitochondrial potential and mitochondrial damage; release of cytochrome c from the mitochondria; cell cycle arrest in G2/M phase in both HeLa and HCT116 cells together with a decrease in the expression of cyclin A and cyclin B) and autophagy (reduction in the expression of the protein p62 in HeLa and HCT116 cells).

Synthesis, characterization, and biological activity of some 2,4-diketo esters containing dehydrozingerone fragment: DNA and protein binding study.

Due to the increased resistance to antibiotics, in recent years there has been a growing interest in the discovery of new antimicrobial agents from different sources. Bacteria that are resistant to most antibiotics are a global public health concern. In order to find a new antimicrobial drug, we synthesized a small series of 2,4-diketo esters and tested them on some gram-positive and gram-negative bacterial strains. Two compounds showed very good antibacterial activity against Staphylococcus aureus and Bacillus subtilis, respectively. Trichophyton mentagrophytes proved to be the most sensitive of the tested species regarding antifungal activity. Also, research was conducted on the biomolecule of bovine serum albumin. Examining these interactions, we concluded that all compounds have the appropriate binding affinity for bovine serum albumin, which is vital. Furthermore, to investigate the potential antitumor activity, interactions with DNA were carried out. Examining the interactions between our compounds and DNA using fluorescence, we concluded that all but one of the compounds interacts with the DNA molecule by intercalation. In addition, a molecular docking study was performed to investigate the binding mode of the tested compounds to DNA and bovine serum albumin. In conclusion, all the results indicate a great potential for the future application of these compounds in clinical practice in the future.

Synthesis, Characterization, and Biological Evaluation of Meldrum's Acid Derivatives: Dual Activity and Molecular Docking Study.

In the presented study, eight novel Meldrum's acid derivatives containing various vanillic groups were synthesized. Vanillidene Meldrum's acid compounds were tested against different cancer cell lines and microbes. Out of nine, three showed very good biological activity against E. coli, and HeLa and A549 cell lines. It is shown that the O-alkyl substituted derivatives possessed better antimicrobial and anticancer activities in comparison with the O-acyl ones. The decyl substituted molecule (3i) has the highest activity against E. coli (MIC = 12.4 µM) and cancer cell lines (HeLa, A549, and LS174 = 15.7, 21.8, and 30.5 µM, respectively). The selectivity index of 3i is 4.8 (HeLa). The molecular docking study indicates that compound 3i showed good binding affinity to DNA, E. coli Gyrase B, and topoisomerase II beta. The covalent docking showed that 3i was a Michael acceptor for the nucleophiles Lys and Ser. The best Eb was noted for the topoisomerase II beta-LYS482-3i cluster.

Anticancer potential of some ß-diketonates: DNA interactions, protein binding properties, and molecular docking study.

With the goal to discover a new antitumor drug with the better or similar effects to existing, a small series of ß-diketonate was tested on a cisplatin-resistant MDA-MB-231 and HeLa tumor cell lines, and nontumor MRC-5 cell line. All compounds showed notable cytotoxicity against both tumor cell lines and good selectivity. Importantly, ß-diketonates displayed greater selectivity than cisplatin, which is the crucial factor for a new antitumor drug candidate. Further, investigations with biomacromolecules such as DNA and serum albumin were performed. Investigations showed that tested compounds bind to DNA through intercalation and have appropriate affinity for binding to bovine serum albumin. In addition, the molecular docking study was performed to investigate more specifically the sites and binding mode of tested ß-diketonate to DNA or bovine serum albumin. In conclusion, all results indicated the big potential of these compounds for application in clinical practice in future.

Synthesis, characterization, HSA/DNA interactions and antitumor activity of new [Ru(η6-p-cymene)Cl2(L)] complexes.

Three new ruthenium(II) complexes were synthesized from different substituted isothiazole ligands 5-(methylamino)-3-pyrrolidine-1-ylisothiazole-4-carbonitrile (1), 5-(methylamino)-3-(4-methylpiperazine-1-yl)isothiazole-4-carbonitrile (2) and 5-(methylamino)-3-morpholine-4-ylisothiazole-4-carbonitrile (3): [Ru(η6-p-cymene)Cl2(L1)]·H2O (4), [Ru(η6-p-cymene)Cl2(L2)] (5) and [Ru(η6-p-cymene)Cl2(L3)] (6). All complexes were characterized by IR, UV-Vis, NMR spectroscopy, and elemental analysis. The molecular structures of all ligands and complexes 4 and 6 were determined by an X-ray. The results of the interactions of CT-DNA (calf thymus deoxyribonucleic acid) and HSA (human serum albumin) with ruthenium (II) complexes reveal that complex 4 binds well to CT-DNA and HSA. Kinetic and thermodynamic parameters for the reaction between complex and HSA confirmed the associative mode of interaction. The results of Quantum mechanics (QM) modelling and docking experiments toward DNA dodecamer and HSA support the strongest binding of the complex 4 to DNA major groove, as well as its binding to IIa domain of HSA with the lowest ΔG energy, which agrees with the solution studies. The modified GOLD docking results are indicative for Ru(p-cymene)LCl··(HSA··GLU292) binding and GOLD/MOPAC(QM) docking/modelling of DNA/Ligand (Ru(II)-N(7)dG7) covalent binding. The cytotoxic activity of compounds was evaluated by MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) assay. Neither of the tested compounds shows activity against a healthy MRC-5 cell line while the MCF-7 cell line is the most sensitive to all. Compounds 3, 4 and 5 were about two times more active than cisplatin, while the antiproliferative activity of 6 was almost the same as with cisplatin. Flow cytometry analysis showed the apoptotic death of the cells with a cell cycle arrest in the subG1 phase.