Search

A novel binuclear Cd complex (1) with hydrazone-based ligand was prepared and characterized by spectroscopy and single crystal X-ray diffraction techniques. Complex 1 reveals a strong pro-apoptotic activity in both human, mammary adenocarcinoma cells (MCF-7) and pancreatic AsPC-1 cancer stem cells (CSCs). While apoptosis undergoes mostly caspase-independent, 1 stimulates the activation of intrinsic pathway with noteworthy down regulation of caspase-8 activity in respect to non-treated controls. Distribution of cells over mitotic division indicates that 1 caused DNA damage in both cell lines, which is confirmed in DNA interaction studies. Compared to 1, cisplatin (CDDP) does not achieve cell death in 2D cultured AsPC-1 cells, while induces different pattern of cell cycle changes and caspase activation in 2D cultured MCF-7 cells, implying that these two compounds do not share similar mechanism of action. Additionally, 1 acts as a powerful inducer of mitochondrial superoxide production with dissipated trans-membrane potential in the majority of the treated cells already after 6 h of incubation. On 3D tumors, 1 displays a superior activity against CSC model, and at 100 μM induces disintegration of spheroids within 2 days of incubation. Fluorescence spectroscopy, along with molecular docking show that compound 1 binds to the minor groove of DNA. Compound 1 binds to the human serum albumin (HSA) showing that the HSA can effectively transport and store 1 in the human body. Thus, our current study strongly supports further investigations on antitumor activity of 1 as a drug candidate for the treatment of highly resistant pancreatic cancer. © 2018 Elsevier Inc.

Thiocarbohydrazones (TCHs) and structurally related molecules are versatile organic compounds which exert antioxidant, anticancer, and other beneficial health effects. The combination of UV/Vis, NMR spectroscopy, and quantum chemical calculations was used to rationalize the experimentally observed increase in the radical scavenging activity upon the addition of water in DMSO solution of TCHs. Mono- and bis(salicylaldehyde) TCHs (compounds 1 and 2) undergo water-induced E-to-Z isomerization which is followed by disruption of intramolecular hydrogen bond, ground state destabilization, and 11 kcal/mol decrease in the bond dissociation enthalpy (BDE). Electron spin delocalization is more pronounced in Z-isomers of 1 and 2. On the other hand, 2-acetylpyridine TCHs (compounds 3 and 4) undergo thione-to-thiol tautomerism which also decreases the BDE and facilitates the hydrogen atom transfer to 2,2-diphenyl-1-picrylhydrazyl radical (DPPH.). The appearance of thiolic -SH group as another reactive site toward free radicals improves the antioxidant activity of 3 and 4. The spin density of 3- and 4-thiol radicals is delocalized over the entire thiocarbohydrazide moiety compared to more localized spin of thione radicals. Additional stabilization of thiol radicals corroborates with the increased antioxidant activity. This study provides the new insights on the solution structure of TCHs, and also highlights the importance of solution structure determination when studying the structure-antioxidant relationships of isomerizable compounds.

Table S1. Statistics of the PCA model generated after 2 FFD cycle. Table S2. Statistics of 3LV PLS model applying different CV procedures. Table S3. Statistics of the PCA model generated after 2 FFD cycle. Table S4. Statistics of 2LV PLS model applying different CV procedures. Experimental Section: materials, methods, general procedure for synthesis of m-TCHs 1-11, general procedure for synthesis of b-TCHs 12-22,. Antimicrobial activity: agar diffusion method, Broth microdilution antimicrobial assay. Alignment-independent 3D QSAR models. Figure S1. 1H NMR spectrum of 3 in DMSO-d6. Figure S2.13C NMR spectrum of 3 in DMSO-d6. Figure S3. 1H NMR spectrum of 4 in DMSO-d6. Figure S4.13C NMR spectrum of 4 in DMSO-d6. Figure S5. 1H NMR spectrum of 6 in DMSO-d6. Figure S6.13C NMR spectrum of 6 in DMSO-d6. Additional references.

Due to the rise of microbial strains resistant to conventional therapies, there is an urgent need for finding the new antimicrobial chemotypes. Heterocyclic compounds such as thiocarbohydrazones (TCHs) are able to interact with many metalloenzymes essential for microbes, while sulfur atom increases lipophilicity which is generally positively correlated with potency. In this paper, we report antibacterial and antifungal activity of twenty-two TCHs toward eight bacterial and three fungal strains. Furthermore, three alignment independent 3D QSAR models based on descriptors derived from molecular interaction fields (MIFs) are developed in order to rationalize structure-activity relationships for activities of TCHs toward S. aureus, P. aeruginosa and C. albicans. Several structural fragments important for biological activity are recognized in each model, and structural modifications which could lead to increased potency are suggested. Designed structures will be synthesized accordingly and tested toward the same microbial strains in order to obtain more potent derivatives.

Cobalt complexes with semi-and thiosemicarbazones of 8-quinolinecarboxaldehyde have been synthesized and characterized by X-ray diffraction analysis. These novel complexes and a previously synthesized cobalt complex with a selenium-based selenosemicarbazone ligand showed myeloid differentiation activity on all trans retinoic acid resistant HL-60 acute myeloid leukaemia cells. They also showed varying levels of cytotoxicity on five human tumor cell lines: cervix carcinoma cells (HeLa), lung adenocarcinoma cells (A549), colorectal adenocarcinoma cells (LS-174), breast carcinoma cells (MDA-MB-361), and chronic myeloid leukaemia (K562) as well as one normal human cell line: fetal lung fibroblast cells (MRC-5). Leukaemia differentiation was most strongly induced by a metal-free oxygen ligand and the selenium ligand, whilst the latter and the cobalt(II) complex with an oxygen ligand showed the strongest dose-dependent cytotoxic activity. In four out of five investigated tumor cell lines, it was of the same order of magnitude as cisplatin. These best compounds, however, had lower toxicity on non-transformed MRC-5 cells than cisplatin.

Fourteen mono- and bis-carbohydrazone ligands have been synthesized and characterized. Antioxidant activity of the substances was investigated together with possible (E)/(Z) isomerization, and explained on the most active antioxidant compound 4 in various dimethyl sulphoxide-water mixtures. The addition of water to the system was involved in the formation of hydrated molecules which was confirmed in NMR after the addition of D2O. The ligands were tested in vitro against Gram-positive and Gram-negative bacteria and fungi, and their activity was discussed in relation to the structure of investigated carbohydrazone.

A new Ni(II) complex, [Ni(L)(H2O)] (1), with diethyl 3,3'-(2,2'-(1,1'-(pyridine-2,6-diyl) bis(ethan-1-yl-1-ylidene)) bis(hydrazin-1-yl-2-ylidene)) bis(3-oxopropanoate) ligand (H2L) was synthesized as a potential chemotherapeutic agent. Polidentate ligand was coordinated to Ni(II) NNN-tridentately, in dianionic form, while monodentate water coordination completed square-planar geometry around metal. Structure in the solution was determined by NMR spectroscopy and the same coordination mode was observed in the solid state using IR spectroscopy and further verified by DFT calculations and electrochemical studies. Thermal stability of 1 was determined in both air and nitrogen atmosphere. Anticancer activity of 1 was investigated on acute monocytic leukemia (THP-1) and pancreatic adenocarcinoma (AsPC-1) cell lines. On THP-1 cells 1 induced powerful apoptotic response (ED50 = 10 +/- 3 mu M), which was revealed to be only partially caspase-dependent, with activation of caspase-8 as the dominant course. This suggested that experimentally validated covalent binding of 1 to DNA is not the only mechanism responsible for programmed cell death. This was supported with experiments on AsPC-1 cells. Although treatment of those cells with 1 resulted in poor apoptotic response, cell cycle changes showed concentration-dependent shifts indicating a dual mechanism of activity. This study also reviews the results of preliminary biological screening, which demonstrates that 1 displays a unique pattern of anticancer activity with at least two mechanisms involved.

Co(III) complex with a 2-hydrazonylthiazole ligand was synthesized and characterized by single-crystal X-ray diffraction. In the inner sphere of the complex, two monoionic ligands are coordinated tridentately forming octahedral geometry around Co(III). Activity of the complex was investigated on MCF-7 breast cancer cell line, with cisplatin (CDDP) as a reference compound. Results showed that after 24-h incubation, Co(III) complex revealed stronger cytotoxic activity compared to CDDP. Treatment of MCF-7 3-D cell model with the complex at 10M concentration achieved complete suppression of spheroid growth in almost the same extent as at 100M. In combination treatments on MCF-7 spheroids, the complex acted synergistically with CDDP, while additive interaction type was achieved when the complex was applied together with paclitaxel.

A comparative study of antitumor activity of mono- and bis-quinoline based (thio) carbohydrazones was investigated by a series of tests on two human malignant cell lines: acute monocytic leukemia (THP-1) and pancreatic adenocarcinoma cancer stem cells (AsPC-1). Thiocarbohydrazones (TCHs) revealed superior pro-apoptotic activity over carbohydrazones (CHs) on both tested cell phenotypes, also displaying multi-target profile activities. Programmed cell death triggered by TCHs was partially caspase-dependent, mainly caspase-8 related. Activity against cancer stem cells (CSCs) was evaluated on 2D monolayers and 3D spheroidal models, where two out of three tested bis-TCHs successfully stimulated apoptosis accompanied by a reduction in size of treated spheres. Additionally, all bis-TCHs induced significant decrease in percentage of CD44-expressing AsPC-1 cells that indicate on their ability to induce reprogramming of CSC phenotype. Current results highly support further assessment of bis-TCHs in order to specify their specific targets in cancer cells and particularly in the CSCs subpopulation.

8-Quinolinecarboxaldehyde selenosemicarbazone (H8qasesc) and its octahedral Co(III) complex were characterized by single crystal X-ray diffraction analysis, spectroscopy methods and cyclic voltammetry. The antineoplastic activity of the ligand and the complex has been assessed on an acute monocytic leukemia cell line (THP-1) and AsPC-1 cancer stem cell (CSC) line derived from a patient suffering from pancreatic adenocarcinoma, with cisplatin (CDDP) as a reference compound. Evaluation involved determination of pro-apoptotic activity, changes in cell cycle distribution, the role of caspase activation in the process of cell death, and the ability of the investigated compounds to challenge reprogramming of the CSC phenotype. Compared to CDDP, treatment with H8qasesc induced a higher apoptotic response in both investigated cell lines. Apoptosis triggered by H8qasesc was highly caspase-dependent but did not include activation of either caspase-8 or -9. According to cell cycle changes H8qasesc delayed the transition of cells during DNA replication but in a manner different from that of CDDP. The ligand did not show nuclease activity on pUC19 plasmid, while docking studies disclosed that it does not have intercalating properties. Treatment of THP-1 cells with the Co(III) complex resulted in a strong toxic response, whereas cell death in the treated AsPC-1 line was not achieved for 24 h. Additionally, the complex concentration-dependently digested plasmid DNA which might be the cause of its cytotoxic activity. Finally, H8qasesc successfully initiated reprogramming of the CSC phenotype in the AsPC-1 cell line.

A new Zn(II)-based potential chemotherapeutic agent was synthesized from the ligand 2-quinolinecarboxaldehyde selenosemicarbazone (Hqasesc). Single crystal X-ray diffraction analysis showed that the Zn(II) complex consists of a cation [Zn(Hqasesc)(2)](2+), two perchlorate anions and one ethanol solvent molecule. The interaction of calf thymus (CT) DNA and human serum albumin (HSA) with the Zn(II) complex was explored using absorption and emission spectral methods, and also has been supported by molecular docking studies. The complex has more affinity to minor DNA groove than major, with no significant intercalation. The HSA interaction studies of the complex revealed the quenching of the intrinsic fluorescence of the HSA through a static quenching mechanism. The antitumor activity of the ligand and the complex against pancreatic adenocarcinoma cell line (AsPC-1) and acute monocytic leukemia (THP-1) cells was evaluated. Both compounds are strong concentration-dependent apoptosis inducers in THP-1 cells. While Hqasesc in AsPC-1 cells induces apoptosis only at the highest concentration, treatment with the Zn complex shows a concentration-dependent apoptotic response, where the treated cells are arrested in the G1-to-S phase accompanied with extensive activation of caspase-8 and -9. These results indicate that the ligand and Zn(II) complex display cell phenotype specific activity.

Two novel Cd(II) and Zn(II) complexes with the condensation product of 2-formylpyridine and selenosemicarbazide were synthesized. The structure of Cd(II) complex was determined by X-ray crystallography. The ligand is coordinated in a neutral form via pyridine and azomethine nitrogen atoms and the selenium donor. The cadmium ion completes its five-coordination by two chloride ligands, forming a square-pyramidal geometry. The structure of Zn(II) complex was established by analysis of spectroscopic data, which indicated coordination of the ligand as a bidentate via the selenium and the azomethine nitrogen atoms. The cytotoxic activity of the newly synthesized complexes, as well as if five structurally related complexes and the ligand evaluated against eight tumor cell lines. The new Cd(II) complex showed the highest activity similar to cisplatin with IC50 less than 10 mu M for all cell lines. Cell cycle distribution and apoptosis study showed that Cd(II) complex and cisplatin might have some similarity in anticancer activity, which was not the case for cisplatin and other studied complexes. Effects of the complexes on matrix metalloproteinases (MMPs) MMP-9 and MMP-2 was also studied. Cd(II) and Zn(II) complexes and cisplatin increased MMP-2 activity in supernatants of tested cells. while Ni(II) complex with the same ligand decreased the activity, implying a possible activity in preventing tumor invasion and metastasis processes. (C) 2010 Elsevier Inc. All rights reserved.