Synthesis, characterization, DNA interactions and biological activity of new palladium(II) complexes with some derivatives of 2-aminothiazoles.

Newly palladium(II) complexes (C1, C2) with derivatives of 2-aminothiazoles (L1 = 2-amino-6-methylbenzothiazole, L2 = 2-amino-6-chlorobenzothiazole), general formula [PdL2Cl2] were synthesized and characterized by elemental microanalyses, IR, NMR spectroscopy and X-ray spectroscopy in case of [Pd(L2)2Cl2]. The kinetic of the substitution reactions of complexes and the nucleophiles, such as guanosine-5'-monophosphate (5'-GMP), tripeptide glutathione (GSH) and amino acid L-methionine (L-Met), were studied by stopped-flow technique. The complex C2 was always more reactive, while the order of the reactivity of the nucleophiles, due to the associative mode of the reaction, was L-Met > GSH > 5'-GMP. In order to determine the type of interactions between palladium(II) complexes and calf thymus DNA (CT-DNA), we used electronic absorption spectroscopy, viscosity measurements, and fluorescence spectroscopic studies, while interactions with bovine serum albumin (BSA) were determined only with fluorescence spectroscopic studies. The observed results confirmed that both complexes bound to DNA by groove binding. The significantly strong interaction with BSA, especially for complex C2, was also observed. In vitro cytotoxic activity was evaluated against four tumor cell lines, 4 T1, CT26, MDA-MB-468, HCT116 and mesenchymal stem cells (mMSC). C1 complex showed higher cytotoxic activity against CT26 cell line. Flow cytometry analysis showed that C1 stimulated apoptosis of tumor cells via inhibition of expression of antiapoptotic Bcl-2 molecule and decelerated proliferation by decreasing Cyclin-D and increasing expression of P21. In vitro antimicrobial activity for ligands and corresponding palladium(II) complexes was investigated by microdilution method and minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) were determined. Tested compounds exhibited selective and moderate activity.

Influence of a Static Magnetic Field on the ⟨100⟩ Growth Rates of Sodium Chlorate Crystals from Aqueous Solution.

The results of the study of the influence of a static magnetic field of 55 ± 3 mT on the growth rates of diamagnetic sodium chlorate crystals in the direction ⟨100⟩ will be presented. Two groups of experiments were performed in the same solution supersaturation range of 0.89-1.78%, the first in zero field conditions, and the second in an applied magnetic field. The results show that crystals nucleated and grown in a static magnetic field have higher mean growth rates in the ⟨100⟩ direction than crystals in a zero field. Also, X-ray analyses suggest that crystals nucleated and grown in a magnetic field may have a higher lattice constant. Possible mechanisms and possible reasons for these phenomena are discussed.

Synthesis of new bile acid-fused tetrazoles using the Schmidt reaction.

A practical and high-yielding Schmidt reaction for the synthesis of fused tetrazoles from bile acid precursors was developed. Mild reaction conditions using TMSN3 instead of hydrazoic acid as an azide source produced good yields of the desired tetrazoles. These conditions could be applied to other steroidal precursors. Additionally, an improved methodology for the synthesis of different ketone and enone precursors from cholic acid, deoxycholic acid, and chenodeoxycholic acid was established. Newly obtained tetrazole derivatives were characterized by NMR and X-ray diffraction spectroscopy. In a number of cases, preliminary antiproliferative tests of new compounds showed strong and selective activity towards certain tumor cell lines.

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.

Synthesis of Camphor-Derived Bis(pyrazolylpyridine) Rhodium(III) Complexes: Structure-Reactivity Relationships and Biological Activity.

Two novel rhodium(III) complexes, namely, [RhIII(X)Cl3] (X = 2 2,6-bis((4 S,7 R)-7,8,8-trimethyl-4,5,6,7-tetrahydro-1 H-4,7-methanoindazol-3-yl)pyridine or 2,6-bis((4 S,7 R)-1,7,8,8-tetramethyl-4,5,6,7-tetrahydro-1 H-4,7-methanoindazol-3-yl)pyridine), were synthesized from camphor derivatives of a bis(pyrazolylpyridine), tridentate nitrogen-donor chelate system, giving [RhIII(H2L*)Cl3] (1a) and [RhIII(Me2L*)Cl3] (1b). A rhodium(III) terpyridine (terpy) ligand complex, [RhIII(terpy)Cl3] (1c), was also synthesized. By single-crystal X-ray analysis, 1b crystallizes in an orthorhombic P212121 system, with two molecules in the asymmetric unit. Tridentate coordination by the N,N,N-donor localizes the central nitrogen atom close to the rhodium(III) center. Compounds 1a and 1b were reactive toward l-methionine (l-Met), guanosine-5'-monophosphate (5'-GMP), and glutathione (GSH), with an order of reactivity of 5'-GMP > GSH > l-Met. The order of reactivity of the RhIII complexes was: 1b> 1a > 1c. The RhIII complexes showed affinity for calf thymus DNA and bovine serum albumin by UV-vis and emission spectral studies. Furthermore, 1b showed significant in vitro cytotoxicity against human epithelial colorectal carcinoma cells. Since the RhIII complexes have similar coordination modes, stability differences were evaluated by density functional theory (DFT) calculations (B3LYP(CPCM)/LANL2DZp). With (H2L*) and (terpy) as model ligands, DFT calculations suggest that both tridentate ligand systems have similar stability. In addition, molecular docking suggests that all test compounds have affinity for the minor groove of DNA, while 1b and 1c have potential for DNA intercalation.

Evaluation of A-ring fused pyridine d-modified androstane derivatives for antiproliferative and aldo-keto reductase 1C3 inhibitory activity.

New A-ring pyridine fused androstanes in 17a-homo-17-oxa (d-homo lactone), 17α-picolyl or 17(E)-picolinylidene series were synthesized and validated by X-ray crystallography, HRMS, IR and NMR spectroscopy. Novel compounds 3, 5, 8 and 12 were prepared by treatment of 4-en-3-one or 4-ene-3,6-dione d-modified androstane derivatives with propargylamine catalyzed by Cu(ii), and evaluated for potential anticancer activity in vitro using human cancer cell lines and recombinant targets of steroidal anti-cancer drugs. Pyridine fusion to position 3,4 of the A-ring may dramatically enhance affinity of 17α-picolyl compounds for CYP17 while conferring selective antiproliferative activity against PC-3 cells. Similarly, pyridine fusion to the A-ring of steroidal d-homo lactones led to identification of new inhibitors of aldo-keto reductase 1C3, an enzyme targeted in acute myeloid leukemia, breast and prostate cancers. One A-pyridine d-lactone steroid 5 also has selective submicromolar antiproliferative activity against HT-29 colon cancer cells. None of the new derivatives have affinity for estrogen or androgen receptors in a yeast screen, suggesting negligible estrogenicity and androgenicity. Combined, our results suggest that A-ring pyridine fusions have potential in modulating the anticancer activity of steroidal compounds.

Dynamic simulation and Doppler Ultrasonography validation of blood flow behavior in Abdominal Aortic Aneurysm.

Criteria for rupture prediction of Abdominal Aortic Aneurysm (AAA) are based only on the diameter of AAA. This method does not consider complex hemodynamic forces exerted on AAA wall. The methodology used in our study combines Computer-Aided Design (CAD) with Computational Fluid Dynamics (CFD). Three-dimensional vascular structures reconstructions were based on Computed Tomography (CT) images and CAD. CFD theory was used for mathematical modeling and simulations. In this way, dynamic behavior of blood flow in bounded three-dimensional space was described. Doppler Ultrasonography (US) was used for model results validation. All simulations were based on medical investigation of 4 patients (male older than 65years) with diagnosed AAA. Good correspondence between computed velocities in AAA and measured values with Doppler US (Patient 1 0.60m·s-1 versus 0.61m·s-1, Patient 2 0.80m·s-1 versus 0.80m·s-1, Patient 3 0.75m·s-1 versus 0.78m·s-1, Patient 4 0.50m·s-1 versus 0.49m·s-1) was noticed. The good agreement between measured and simulated velocities validates our methodology and the other data available from simulations (eg. von Misses stress) could be used to provide useful information about the possibility of AAA rupture.

Kinetic and mechanistic study on the reactions of ruthenium(ii) chlorophenyl terpyridine complexes with nucleobases, oligonucleotides and DNA.

In this study, we investigated the ability of Ru(ii) polypyridyl complexes to act as DNA binders. The substitution reactions of three Ru(ii) chlorophenyl terpyridine complexes, i.e. [Ru(Cl-Ph-tpy)(en)Cl]Cl (1), [Ru(Cl-Ph-tpy)(dach)Cl]Cl (2) and [Ru(Cl-Ph-tpy)(bpy)Cl]Cl (3) (Cl-Ph-tpy = 4'-(4-chlorophenyl)-2,2':6',2''-terpyridine, en = 1,2-diaminoethane, dach = 1,2-diaminocyclohexane, bpy = 2,2'-bipyridine), with a mononucleotide guanosine-5'-monophosphate (5'-GMP) and oligonucleotides such as fully complementary 15-mer and 22-mer duplexes with a centrally located GG-binding site for DNA, and fully complementary 13-mer duplexes with a centrally located GG-binding site for RNA were studied quantitatively by UV-Vis spectroscopy. Duplex RNA reacts faster with complexes 1-3 than duplex DNA, while shorter duplex DNA (15mer GG) reacts faster compared with 22mer GG duplex DNA. The measured enthalpies and entropies of activation (ΔH≠ > 0, ΔS≠ < 0) support an associative mechanism for the substitution process. 1H NMR spectroscopy studies performed on complex 3 demonstrated that after the hydrolysis of the Cl ligand, it is capable to interact with guanine derivatives (i.e., 9-methylguanine (9MeG) and 5'-GMP) through N7, forming monofunctional adducts. The molecular structure of the cationic compound [Ru(Cl-Ph-tpy)(bpy)Cl]Cl (3) was determined in the solid state by X-ray crystallography. The interactions of 1-3 with calf thymus (CT) and herring testes (HT) DNA were examined by stopped-flow spectroscopy, in which HT DNA was sensibly more reactive than CT DNA. The reactivity towards the formation of Ru-DNA adducts was also revealed by a gel mobility shift assay, showing that complexes 1 and 2 have a stronger DNA unwinding ability compared to complex 3. Overall, the complexes with bidentate aliphatic diamines proved to be superior to those with bpy in terms of capability to bind to the here studied biomolecules.

Synthesis, structural analysis and antitumor activity of novel 17α-picolyl and 17(E)-picolinylidene A-modified androstane derivatives.

The heterocyclic ring at C-17 position of the androstane compounds plays an important role in biological activity. The aim of the present study was to synthesize and evaluate potential antitumor activity of different A-modified 17α-picolyl and 17(E)-picolinylidene androstane derivatives. In several synthetic steps, novel derivatives bearing the hydroximino, nitrile or lactame functions in A-ring were synthesized and characterized according to the spectral data, by mass analysis as well as XRD analysis (compounds 6, 13 and 15). The structurally most promising compounds 6, 11-17 were investigated as antitumor agents. The in vitro antiproliferative activity was evaluated against six human cancer cell lines: estrogen receptor negative (ER-) breast adenocarcinoma (MDA-MB-231); estrogen receptor positive (ER+) breast adenocarcinoma (MCF-7); prostate cancer (PC-3); human cervical carcinoma (HeLa); lung adenocarcinoma (A549) and colon adenocarcinoma (HT-29) using MTT assay. The results of the 48h incubation time in vitro tests showed that compound 15 was the most effective against PC-3 (IC50 6.6µM), compound 17 against MCF-7 (IC50 7.9µM) cells, while compound 16 exhibited strong antiproliferative effect against both, MCF-7 (IC50 1.7µM) and PC-3 (IC50 8.7µM) cancer cells. It was also found that compounds 16 and 17 induced apoptosis in MCF-7 cells (dicyano derivative 17 stronger then dioxime 16 and reference formestane), with no distinct changes in the cell cycle of MCF-7 cells.

Determination of 17α-hydroxylase-C17,20-lyase (P45017α) enzyme activities and their inhibition by selected steroidal picolyl and picolinylidene compounds.

17α-hydroxylase-C17,20-lyase (P45017α) is a key regulator enzyme of the steroid hormone biosynthesis in both the adrenals and the testes. Inhibition of this enzyme can block androgen synthesis in an early step, and may thereby be useful in the treatment of several androgen-dependent diseases. We developed radio-substrate in vitro incubation methods for the determination of the distinct 17α-hydroxylase and C17,20-lyase activities of the enzyme using rat testicular homogenate as enzyme source. With this method we have studied the inhibiting activity of selected steroidal picolyl and picolinylidene compounds. Tests revealed a substantial inhibitory action of the 17-picolinyliden-androst-4-en-3-one compound.

Synthesis and anticancer cell potential of steroidal 16,17-seco-16,17a-dinitriles: identification of a selective inhibitor of hormone-independent breast cancer cells.

We report the synthesis of steroidal 16,17-seco-16,17a-dinitriles and investigate their antitumor cell properties. Compounds were evaluated for anticancer potential by in vitro antiproliferation studies, molecular docking and virtual screening. Several compounds inhibit the growth of breast and prostate cancer cell lines (MCF-7, MDA-MB-231 and PC3), and/or cervical cancer cells (HeLa). Supporting this, molecular docking predicts that steroidal 16,17-seco-16,17a-dinitriles could bind with high affinity to multiple molecular targets of breast and prostate cancer treatment (aromatase, estrogen receptor α, androgen receptor and 17α-hydroxylase) facilitated by D-seco flexibility and nitrile-mediated contacts. Thus, 16,17-seco-16,17a-dinitriles may be useful for the design of inhibitors of multiple steroidogenesis pathways. Strikingly, 10, a 1,4-dien-3-on derivative, displayed selective submicromolar antiproliferative activity against hormone-dependent (MCF-7) and -independent (MDA-MB-231) breast cancer cells (IC50 0.52, 0.11µM, respectively). Ligand-based 3D similarity searches suggest AKR1C, 17ß-HSD and/or 3ß-HSD subfamilies as responsible for this antiproliferative activity, while fast molecular docking identified AKR1C and ERß as potential binders-both targets in the treatment of hormone-independent breast cancers.

Antihormonal potential of selected D-homo and D-seco estratriene derivatives.

Since many estrogen derivatives exhibit anti-hormone or enzyme inhibition potential, a large number of steroidal derivatives have been synthesised from appropriate precursors, in order to obtain potential therapeutics for the treatment of hormone-dependent cancers. In molecular docking studies, based on X-ray crystallographic analysis, selected D-homo and D-seco estratriene derivatives were predicted to bind strongly to estrogen receptor α (ERα), aromatase and 17,20 lyase, suggesting they could be good starting compounds for antihormonal studies. Test results in vivo suggest that these compounds do not possess estrogenic activity, while some of them showed weak anti-estrogenic properties. In vitro anti-aromatase and anti-lyase assays showed partial inhibition of these two enzymes, while some compounds activated aromatase. Aromatase activators are capable of promoting estrogen synthesis for treatment of pathological conditions caused by estrogen depletion, e.g. osteopenia or osteoporosis.

Microwave assisted synthesis and biomedical potency of salicyloyloxy and 2-methoxybenzoyloxy androstane and stigmastane derivatives.

A convenient microwave assisted solvent free synthesis as well as conventional synthesis of salicyloyloxy and 2-methoxybenzoyloxy androstane and stigmastane derivatives 7-19 from appropriate steroidal precursors 1-6 and methyl salicylate is reported. The microwave assisted synthesis in most cases was more successful regarding reaction time and product yields. It was more environmentally friendly too, compared to the conventional method. The antioxidant activity and cytotoxicity of the synthesized derivatives were evaluated in a series of in vitro tests, as well as their inhibition potency exerted on hydroxysteroid dehydrogenase enzymes (Δ(5)-3ßHSD, 17ßHSD2 and 17ßHSD3). All of the tested compounds were effective in OH radical neutralization, particularly compounds 9, 11 and 14, which exhibited about 100-fold stronger activity than commercial antioxidants BHT and BHA. In DPPH radical scavenging new compounds were effective, but less than reference compounds. 2-Methoxybenzoyl ester 10 exhibited strong cytotoxicity against MDA-MB-231 cells. Most compounds inhibited growth of PC-3 cells, where salicyloyloxy stigmastane derivative 15 showed the best inhibition potency. Compounds 9, 10 and 11 were the best inhibitors of 17ßHSD2 enzyme. X-ray structure analysis and molecular mechanics calculations (MMC) were performed for the best cytotoxic agents, compounds 10 and 15. A comparison of crystal and MMC structures of compounds 10 and 15 revealed that their molecules conformations are stable even after releasing of the influence of crystalline field and that the influence of crystal packing on molecular conformation is not predominant.

Synthesis of novel palladium(II) complexes with oxalic acid diamide derivatives and their interaction with nucleosides and proteins. Structural, solution, and computational study.

Novel palladium complexes, KH[Pd(obap)]2·3H2O (3) with oxamido-N-aminopropyl-N'-benzoic acid and [Pd(apox)] (4) with N,N'-bis(3-aminopropyl)ethanediamide, were synthesized. Exhaustive synthetic, solution and structural studies of the two Pd(ii) complexes are reported. The binary and ternary systems of the Pd(ii) ion with H2apox or H3obap as primary ligands and nucleosides (Ado or Cyt) as secondary ligands, are investigated in order to better understand their equilibrium chemistry. The relative stabilities of the ternary complexes are determined and compared with those of the corresponding binary complexes in terms of their Δlog K values. The species distribution of all complexes in solution is evaluated. Fluorescence spectroscopy data shows that the fluorescence quenching of HSA is a result of the formation of the [PdL]-HSA complex. The structure of complex 3 is confirmed using X-ray crystallography. The results are compared to those obtained for palladium complexes of similar structures. Density functional theory (DFT) has been applied for modelling and energetic analysis purposes. The nature of the Pd-N(O) bond interaction is analyzed using NBO. We report here docking simulation experiments in order to predict the most probable mechanism of pro-drug-action. The next free binding energy order of the best scores from the [PdL]-DNA docking simulations, cis-[Pt(NH3)2(H2O)2](2+) > [Pd(obap)] > [Pd(mda)], has been observed in the case of DNA alteration. For the ER and cytosolic stress mechanisms the results of the docking simulations to the chaperons Grp78 and Hsc70 are promising for possible applications as potent protein inhibitors (Ki of [Pd(mda)]/GRP78 being ∼66 µM and Ki for [Pd(obap)]/HSC70 being 14.39 µM).

17(E)-picolinylidene androstane derivatives as potential inhibitors of prostate cancer cell growth: antiproliferative activity and molecular docking studies.

We report a rapid and efficient synthesis of A-ring modified 17α-picolyl and 17(E)-picolinylidene androstane derivatives from dehydroepiandrosterone. Compounds were validated spectroscopically and structurally characterized by X-ray crystallography. Virtual screening by molecular docking against clinical targets of steroidal anticancer drugs (ERα, AR, Aromatase and CYP17A1) suggests that 17(E)-picolinylidene, but not 17α-picolyl androstanes could specifically interact with CYP17A1 (17α-hydroxylase) with similar geometry and affinity as Abiraterone, a 17-pyridinyl androstane drug clinically used in the treatment of prostate cancer. In addition, several 17(E)-picolinylidene androstanes demonstrated selective antiproliferative activity against PC3 prostate cancer cells, which correlates with Abiraterone antiproliferative activity and predicted CYP17A1 binding affinities. Based on these preliminary results, 17(E)-picolinylidene androstane derivatives could be a promising starting point for the development of new compounds for the treatment of prostate cancer.

Synthesis and biological evaluation of some new A,B-ring modified steroidal D-lactones.

Starting from the D-homo lactones of androst-4-en-3-one 3 and 4, prepared from 1 and 2, the new 17a homolactones 5-12, 14 and 15, were synthesized. The 4-hydroxy compounds 9 and 10 were obtained through the reaction of 4alpha,5alpha- (5 and 7) and 4beta,5beta- (6 and 8) epoxides with formic acid. The epoxides 5 and 6 were prepared from compound 3, and epoxides 7 and 8 from compound 4 by oxidation with H(2)O(2) under basic conditions. Compound 1 served as a starting substance for obtaining lactones 11-13. Oxidation of compound 1 with m-chloroperbenzoic acid yielded 11 and 12, but compound 13 gave 14. Compound 15 was obtained from 13 by oxidation with H(2)O(2) under basic conditions. The structures of epoxides 6 and 14 were confirmed by X-ray structural analysis. Cytotoxic activity against three tumor cell lines (human breast adenocarcinoma ER+, MCF-7, human breast adenocarcinoma ER-, MDA-MB-231, and prostate cancer PC3) was evaluated. Compounds 6 and 14 showed strong activity against PC3, the IC(50) being 10.6 and 2.2 microM, respectively, whereas compounds 3 and 8 showed strong activity against MDA-MB-231 (IC(50) is 9.3 and 3.6 microM, respectively). Aromatase inhibition assay showed that the tested compounds 9, 10, and 14 possess lower activity compared to formestane.

Synthesis and anti-aromatase activity of some new steroidal D-lactones.

Starting from D-seco derivatives of 5-androstene 1-3, the D-homo lactones, 4 and 5, were synthesized. By the Oppenauer oxidation and/or by dehydration of 4 and 5 with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil), the corresponding D-lactones 6-12 were obtained. The structures of 6 and 10 were unambiguously proved by the appropriate X-ray structural analysis. Anti-aromatase assay showed that tested compounds possess inhibition potency, however, two to four times smaller (IC50 from 0.2 to 0.7 microM, respectively) in comparison to aminoglutethimide (AG).