Combined Effect of Caspase-Dependent and Caspase-Independent Apoptosis in the Anticancer Activity of Gold Complexes with Phosphine and Benzimidazole Derivatives.

Since the potential anticancer activity of auranofin was discovered, gold compounds have attracted interest with a view to developing anticancer agents that follow cytotoxic mechanisms other than cisplatin. Two benzimidazole gold(I) derivatives containing triphenylphosphine (Au(pben)(PPh3)) (1) or triethylphosphine (Au(pben)(PEt3)) (2) were prepared and characterized by standard techniques. X-ray crystal structures for 1 and 2 were solved. The cytotoxicity of 1 and 2 was tested in human neuroblastoma SH-SY5Y cells. Cells were incubated with compounds for 24 h with concentrations ranging from 10 µM to 1 nM, and the half-maximal inhibitory concentration (IC50) was determined. 1 and 2 showed an IC50 of 2.7 and 1.6 µM, respectively. In order to better understand the type of cell death induced by compounds, neuroblastoma cells were stained with Annexin-FITC and propidium iodide. The fluorescence analysis revealed that compounds were inducing apoptosis; however, pre-treatment with the caspase inhibitor Z-VAD did not reduce cell death. Analysis of compound effects on caspase-3 activity and reactive oxygen species (ROS) production in SH-SY5Y cells revealed an antiproliferative ability mediated through oxidative stress and both caspase-dependent and caspase-independent mechanisms.

Mono and dinuclear phosphinegold(I) sulfanylcarboxylates: influence of nuclearity and substitution of PPh3 for PEt3 on cytotoxicity.

Gold complexes of the type [Au(PEt3)(Hxspa)] were prepared by reacting triethylphosphinegold(I) chloride in ethanol/water (8:1) with the 3-(aryl)-2-sulfanylpropenoic acids H2xspa [x=p=3-phenyl-; f=3-(2-furyl)-; t=3-(2-thienyl)-; py=3-(2-pyridyl); Clp=3-(2-Chlorophenyl)-; -o-mp=3-(2-methoxyphenyl)-; -p-mp=3-(4-methoxyphenyl)-; -o-hp=3-(2-hydroxyphenyl)-; -p-hp=3-(4-hydroxyphenyl)-; -diBr-o-hp=3-(3,5-dibromo-2-hidroxyphenyl-); spa=2-sulfanylpropenoato] or 2-cyclopentylidene-2-sulfanylacetic acid (H2cpa) and KOH in a 1:1:1 mole ratio. The compounds were characterized by IR spectroscopy and FAB mass spectrometry and by (1)H, (13)C and (31)P NMR spectroscopy. The in vitro antitumor activity of these and of the previously described dinuclear [(AuPEt3)2(xspa)] complexes against the HeLa-229, A2780 and A2780cis cell lines was determined and compared with those of the analogous PPh3 complexes. The results show that the substitution of the PPh3 ligand by PEt3 is particularly effective in increasing the cytotoxicity of the dinuclear [(AuPR3)2(xspa)] complexes, giving rise to compounds that are significantly more active than cisplatin against the aforementioned cell lines. In addition, and as a preliminary test for nephrotoxicity, the cytotoxicity of the most active compounds against the normal renal LCC-PK1 cell line was evaluated and compared with that of cisplatin.

Dinuclear triphenylphosphinegold(I) sulfanylcarboxylates: Synthesis, structure and cytotoxic activity against cancer cell lines.

Compounds of the type [(AuPPh(3))(2)(xspa)]; H(2)xspa [x:p=3-phenyl-, f=3-(2-furyl)-, t=3-(2-thienyl)-, -o-py=3-(2-pyridyl)-, Clp=3-(2-chlorophenyl)-, -o-mp=3-(2-methoxyphenyl)-, -p-mp=3-(4-methoxyphenyl)-, -o-hp=3-(2-hydroxyphenyl)-, -p-hp=3-(4-hydroxyphenyl)-, -diBr-o-hp=3-(3,5-dibromo-2-hydroxyphenyl)-; spa=2-sulfanyl propenoato] were synthesized and characterized by IR and NMR ((1)H, (13)C and (31)P) spectroscopy and by FAB mass spectrometry. The structures of [(AuPPh(3))(2)(Clpspa)], [(AuPPh(3))(2)(o-hpspa)], [(AuPPh(3))(2)(p-hpspa)].MeOH and [(AuPPh(3))(2)(diBr-o-hpspa)].2Me(2)CO show the dinuclear nature of the complexes with the two gold atoms, one of which is also O-bonded to an O atom of the carboxylate group, bonded to the S atom. The in vitro antitumor activities against the HeLa-229, A2780 and A2780cis cell lines were determined and the compounds were found to be highly effective, in particular against the A2780cis cell line, with eight of the nine compounds having IC(50) values better than that of cisplatin. This behavior is indicative of a high ability to circumvent the cellular resistance to this drug.

Complex network spectral moments for ATCUN motif DNA cleavage: first predictive study on proteins of human pathogen parasites.

The development of methods that can predict the metal-mediated biological activity based only on the 3D structure of metal-unbound proteins has become a goal of major importance. This work is dedicated to the amino terminal Cu(II)- and Ni(II)-binding (ATCUN) motifs that participate in the DNA cleavage and have antitumor activity. We have calculated herein, for the first time, the 3D electrostatic spectral moments for 415 different proteins, including 133 potential ATCUN antitumor proteins. Using these parameters as input for Linear Discriminant Analysis, we have found a model that discriminates between ATCUN-DNA cleavage proteins and nonactive proteins with 91.32% Accuracy (379 out of 415 of proteins including both training and external validation series). Finally, the model has predicted for the first time the DNA cleavage function of proteins from the pathogen parasites. We have predicted possible ATCUN-like proteins with a probability higher than 99% in nine parasite families such as Trypanosoma, Plasmodium, Leishmania, or Toxoplasma. The distribution by biological function of the ATCUN proteins predicted has been the following: oxidoreductases 70.5%, signaling proteins 62.5%, lyases 58.2%, membrane proteins 45.5%, ligases 44.4%, hydrolases 41.3%, transferases 39.2%, cell adhesion proteins 34.5%, metal binders 33.5%, translation proteins 25.0%, transporters 16.7%, structural proteins 9.1%, and isomerases 8.2%. The model is implemented at http://miaja.tic.udc.es/Bio-AIMS/ATCUNPred.php.

Synthesis, structure and cytotoxicity studies of diisopropylammonium and triethylammonium salts of triphenylphosphinegold(I) sulfanylcarboxylates.

Compounds of the type [HQ][Au(PPh(3))(xspa)] and [HP][Au(PPh(3))(xspa)] {HQ=diisopropylammonium; HP=triethylammonium; H(2)xspa=3-aryl-2-sulfanylpropenoic acids [x: p=3-phenyl-, f=3-(2-furyl)-, t=3-(2-thienyl)-, -o-py=3-(2-pyridyl)-, Clp=3-(2-chlorophenyl)-, -o-mp=3-(2-methoxyphenyl)-, -p-mp=3-(4-methoxyphenyl)-, -o-hp=3-(2-hydroxyphenyl)-, -p-hp=3-(4-hydroxyphenyl)-, diBr-o-hp=3-(3,5-dibromo-2-hydroxyphenyl]} were synthesized and characterized by IR and NMR ((1)H, (13)C and (31)P) spectroscopy and by FAB mass spectrometry. The structures of [HQ][Au(PPh(3))(Clpspa)] and [HQ][Au(PPh(3))(-o-mpspa)] show that the crystal contains hydrogen-bonded diisopropylammonium cations and [Au(PPh(3))(xspa)](-) anions. The anions in the two compounds have different structures, with the carboxylate group either coordinated or not coordinated to the gold atom, respectively. The in vitro antitumour activities against the HeLa-229, A2780 and A2780cis cell lines were determined for all complexes. The diisopropylammonium derivatives were generally found to be more active, in particular against the A2780cis cell line, and showed a high ability to circumvent the cellular resistance to cisplatin.

New Pd(II) and Pt(II) complexes with N,S-chelated pyrazolonate ligands: molecular and supramolecular structure and preliminary study of their in vitro antitumoral activity.

New Pd(II) and Pt(II) complexes [ML2] (HL=a substituted 2,5-dihydro-5-oxo-1H-pyrazolone-1-carbothioamide) have been synthesized by reacting K2MCl4 (M=Pd, Pt) or Pd(OAc)2 with beta-ketoester thiosemicarbazones. The structures of seven of these complexes were determined by X-ray diffraction. Although all exhibit a distorted square-planar coordination with trans- or (in one case) cis-[MN2S2] kernels, their supramolecular arrangements vary widely from isolated molecules to 3D-networks. The in vitro antitumoral assays performed with two HL ligands and their metal complexes showed significant cytostatic activity for the latter, with the most active [ML2] derivative (a palladium complex) being about sixteen times more active than cis-DDP against the cisplatinum-resistant cell line A2780cisR.

Synthesis, structure and cytotoxicity of triphenylphosphinegold(I) sulfanylpropenoates.

The reaction of triphenylphosphinegold(I) chloride in ethanol in a 1:1 molar ratio with the 3-(aryl)-2-sulfanylpropenoic acids H(2)xspa [x: p=3-phenyl-, Clp=3-(2-chlorophenyl)-, -o-mp=3-(2-methoxyphenyl)-, -p-mp=3-(4-methoxyphenyl)-, -o-hp=3-(2-hydroxyphenyl)-, -p-hp=3-(4-hydroxyphenyl)-, diBr-o-hp=3-(3,5-dibromo-2-hydroxyphenyl)-, f=3-(2-furyl)-, t=3-(2-thienyl)-, -o-py=3-(2-pyridyl)-; spa=2-sulfanylpropenoato] gave compounds of the type [Au(PPh(3))(Hxspa)], which were isolated and characterized as solids by elemental analysis, IR spectroscopy and FAB mass spectrometry and in solution by (1)H, (13)C and (31)P NMR spectroscopy. The structures of the complexes [Au(PPh(3))(HClpspa)], [Au(PPh(3))(H-o-mpspa)] and [Au(PPh(3))(H-p-mpspa)].2/3C(3)H(6)O were determined by X-ray diffractometry. Hydrogen bonding was found along with Au-S and Au-P bonds in all cases and weak pi-pi stacking was found in the H-p-mpspa derivative. The in vitro antitumour activities against the HeLa-229, A2780 and A2780cis cell lines were determined for all complexes.

Computational chemistry approach to protein kinase recognition using 3D stochastic van der Waals spectral moments.

Three-dimensional (3D) protein structures now frequently lack functional annotations because of the increase in the rate at which chemical structures are solved with respect to experimental knowledge of biological activity. As a result, predicting structure-function relationships for proteins is an active research field in computational chemistry and has implications in medicinal chemistry, biochemistry and proteomics. In previous studies stochastic spectral moments were used to predict protein stability or function (González-Díaz, H. et al. Bioorg Med Chem 2005, 13, 323; Biopolymers 2005, 77, 296). Nevertheless, these moments take into consideration only electrostatic interactions and ignore other important factors such as van der Waals interactions. The present study introduces a new class of 3D structure molecular descriptors for folded proteins named the stochastic van der Waals spectral moments ((o)beta(k)). Among many possible applications, recognition of kinases was selected due to the fact that previous computational chemistry studies in this area have not been reported, despite the widespread distribution of kinases. The best linear model found was Kact = -9.44 degrees beta(0)(c) +10.94 degrees beta(5)(c) -2.40 degrees beta(0)(i) + 2.45 degrees beta(5)(m) + 0.73, where core (c), inner (i) and middle (m) refer to specific spatial protein regions. The model with a high Matthew's regression coefficient (0.79) correctly classified 206 out of 230 proteins (89.6%) including both training and predicting series. An area under the ROC curve of 0.94 differentiates our model from a random classifier. A subsequent principal components analysis of 152 heterogeneous proteins demonstrated that beta(k) codifies information different to other descriptors used in protein computational chemistry studies. Finally, the model recognizes 110 out of 125 kinases (88.0%) in a virtual screening experiment and this can be considered as an additional validation study (these proteins were not used in training or predicting series).

3D-QSAR study for DNA cleavage proteins with a potential anti-tumor ATCUN-like motif.

Genomics projects have elucidated several genes that encode protein sequences. Subsequently, the advent of the proteomics age has enabled the synthesis and 3D structure determination for these protein sequences. Some of these proteins incorporate metal atoms but it is often not known whether they are metal-binding proteins and the nature of the biological activity is not understood. Consequently, the development of methods to predict metal-mediated biological activity of proteins from the 3D structure of metal-unbound proteins is a goal of major importance. More specifically, the amino terminal Cu(II)- and Ni(II)-binding (ATCUN) motif is a small metal-binding site found in the N-terminus of many naturally occurring proteins. The ATCUN motif participates in DNA cleavage and has anti-tumor activity. In this study, we calculated average 3D electrostatic potentials (xi(k)) for 265 different proteins including 133 potential ATCUN anti-tumor proteins. We also calculated xi(k) values for the total protein or for the following specific protein regions: the core, inner, middle, and outer orbits. A linear discriminant analysis model was subsequently developed to assign proteins into two groups called ATCUN DNA-cleavage proteins and non-active proteins. The best model found was: ATCUN=1.15.xi(1)(inner)+2.18.xi(5)(middle)+27.57.xi(0)(outer)-27.57.xi(0)(total)+0.09. The model correctly classified 182 out of 197 (91.4%) and 61 out of 66 (92.4%) proteins in training and external predicting series', respectively. Finally, desirability analysis was used to predict the values for the electrostatic potential in one single region and the combined values in two regions that are desirable for ATCUN-like proteins. To the best of our knowledge, the present work is the first study in which desirability analysis has been used in protein quantitative-structure-activity-relationship (QSAR).