Copper(II) complexes [Cu(H2O)2 (L1)(phen)](ClO4) (1) and [Cu(H2O)(L2)(phen)](ClO4) (2) (HL1 = naringenin; HL2 = hesperetin) were obtained, in which an anionic flavonoid ligand is attached to the metal center along with 1,10-phenanthroline (phen) as co-ligand. Complexes (1) and (2) were assayed for their cytotoxic activity against A549 lung carcinoma and against normal lung fibroblasts (LL-24) and human umbilical vein endothelial cells (HUVEC). We found IC50 = 16.42 µM (1) and IC50 = 5.82 µM (2) against A549 tumor cells. Complexes (1) and (2) exhibited slight specificity, being more cytotoxic against malignant than against non-malignant cells. 1 and 2 induced apoptosis on A549 cells in a mitochondria-independent pathway, and showed antioxidant activity. The antioxidant effect of the complexes could possibly improve their apoptotic action, most likely by a PI3K-independent reduction of autophagy. Complexes (1) and (2) interact in vitro with calf thymus DNA by an intercalative binding mode. EPR data indicated that 1 and 2 interact with human serum albumin (HSA) forming mixed ligand species.
Complexes [Ag(HCrPh)]NO·2HO (1) and [Ag(HCrpClPh)]NO (2) were obtained with 3-formyl-6-methylchromone-phenyl hydrazone (HCrPh, HL1) and 3-formyl-6-methylchromone-para-chloro-phenyl hydrazone (HCrpClPh, HL2). Although the hydrazones were inactive, upon coordination to silver(I) antifungal activity significantly improved against several Candida strains. Complexes (1-2) revealed to be more active than silver nitrate, silver sulfadiazine and the reference drug nystatin against Candida parapsilosis. The cytotoxic activities of the hydrazones and their silver(I) complexes were evaluated in comparison with cisplatin on B16F10 (metastatic melanoma) and Melan-a (non-tumorigenic melanocyte) cells. The hydrazones showed low cytotoxicity against B16F10 cells, reducing only about 20% of cell viability at the concentration of 10 μM. Upon coordination to silver(I) the cytotoxic effect did not appreciably change in complex (1) while complex (2) proved to be as cytotoxic as cisplatin and much more cytotoxic than both the free ligand and silver nitrate at 1 μM. Both complexes (1) and (2) were less active than cisplatin on non-malignant Melan-a cells, indicating that these compounds might promote less damage on normal cells.
This article describes the synthesis and characterization of a new complex, [Pd(Ph2PzTSC)2], formed between palladium(II) and 1,3-diphenylpyrazole-4-carboxaldehyde thiosemicarbazone ligand as a strategy for antimicrobial activity improvement the synthesized complex. The metal coordination leads to an improvement of ligand pharmacological activities and synergistic effects involving both metal ion as the ligand. The bidentate ligand is coordinated to metal ion through the azomethine nitrogen atoms and the sulphur in the form of thiol by deprotonation of the NH-C=S group. The antimicrobial activity of these new compounds was evaluated against gram-negative (Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) and gram-positive (Staphylococcus aureus and Bacillus thuringiensis) bacteria and two yeasts strains (Candida albicans and Saccharomyces cerevisiae). A comparison between the antimicrobial activity of the complex and that of the free ligand revealed that the coordination of Pd(II) improved the activity.
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