Juan Carlos García-Ramos

Intercalation processes of copper complexes in DNA

The family of anticancer complexes that include the transition metal copper known as Casiopeínas® shows promising results. Two of these complexes are currently in clinical trials. The interaction of these compounds with DNA has been observed experimentally and several hypotheses regarding the mechanism of action have been developed, and these include the generation of reactive oxygen species, phosphate hydrolysis and/or base-pair intercalation. To advance in the understanding on how these ligands interact with DNA, we present a molecular dynamics study of 21 Casiopeínas with a DNA dodecamer using 10 μs of simulation time for each compound. All the complexes were manually inserted into the minor groove as the starting point of the simulations. The binding energy of each complex and the observed representative type of interaction between the ligand and the DNA is reported. With this extended sampling time, we found that four of the compounds spontaneously flipped open a base pair and moved inside the resulting cavity and four compounds formed stacking interactions with the terminal base pairs. The complexes that formed the intercalation pocket led to more stable interactions.

Analysis of the DNA Interaction of Copper Compounds Belonging to the Casiopeínas® Antitumoral Series

Casiopeínas® are mixed-chelate copper complexes with antitumor tested potential. Their activity, both in vitro and in vivo, as antiproliferative, cytotoxic, and genotoxic drugs has been assessed. Biological results of these copper compounds have deserved some of them entering clinical trials. Significant efforts have been devoted to the in-depth identification of their mechanism of action. Using gel electrophoresis analysis, we have previously shown that the interaction of the Casiopeínas® Cas II-gly, [Cu(4,7-dimethyl-1,10-phenanthroline)(glycinate)]NO3 with DNA, triggers the cleavage of the biomolecule by a free radical mechanism. In this work, we further study the behavior of different complexes of the same Casiopeínas® series also including glycinate as co-ligand {Cas VI-gly (5,6 dimethyl-1,10-phenanthroline glycinato copper(II) nitrate), Cas VII-gly (1,10-phenanthroline glycinato copper(II) nitrate), and Cas IX-gly (2,2′-bipyridine glycinato copper(II) nitrate)} and of a Casiopeínas® with a different co-ligand (Cas III-Cs; 4,7-dimethyl-1,10-phenanthroline salicylaldehydato-copper(II) nitrate). While all of them produce DNA degradation, the performance in the presence of a radical scavenger suggests the existence of differences in their mechanism of interaction with DNA.

Potential Amoebicidal Activity of Hydrazone Derivatives: Synthesis, Characterization, Electrochemical Behavior, Theoretical Study and Evaluation of the Biological Activity

Four new hydrazones were synthesized by the condensation of the selected hydrazine and the appropriate nitrobenzaldehyde. A complete characterization was done employing 1H- and 13C-NMR, electrochemical techniques and theoretical studies. After the characterization and electrochemical analysis of each compound, amoebicidal activity was tested in vitro against the HM1:IMSS strain of Entamoeba histolytica. The results showed the influence of the nitrobenzene group and the hydrazone linkage on the amoebicidal activity. meta-Nitro substituted compound 2 presents a promising amoebicidal activity with an IC50 = 0.84 μM, which represents a 7-fold increase in cell growth inhibition potency with respect to metronidazole (IC50 = 6.3 μM). Compounds 1, 3, and 4 show decreased amoebicidal activity, with IC50 values of 7, 75 and 23 µM, respectively, as a function of the nitro group position on the aromatic ring. The observed differences in the biological activity could be explained not only by the redox potential of the molecules, but also by their capacity to participate in the formation of intra- and intermolecular hydrogen bonds. Redox potentials as well as the amoebicidal activity can be described with parameters obtained from the DFT analysis.

Synthesis, characterization and evaluation of the substituent effect on the amoebicide activity of new hydrazone derivatives

A series of 10 hydrazones were synthesized by condensation of the selected hydrazine and the appropriate aldehyde. After the characterization and electrochemical analysis of each compound, amoebicidal activity was evaluated in vitro against the HM1:IMSS strain of Entamoeba histolytica. The results showed the influence of the nitrobenzene group and the hydrazone linkage over the amoebicidal activity. Compound 1 presents a promising amoebicidal activity with an IC50 = 0.98 μM, which represents a 7-fold increase in the potency of cell growth inhibition with respect to metronidazole (IC50= 6.8 μM). Moreover, compounds 2 and 4 present an amoebicidal activity comparable to the reference compound. These results show that the electronic environment of hydrazone derivatives reflected in redox potential values of the hydrazone linkage and the nitro group plays a fundamental role in the amoebicidal activity. The molecular structure of compound 1 was reported.

Abstract CT408: Phase I study of one mixed chelates copper(II) compound, Casiopeína CasIIIia with antitumor activity and its mechanism of action

Metal complexes have gained a growing interest as pharmaceuticals for their use as diagnostic agents or as chemotherapeutic drugs[1]. In our group some efforts have been done in the development of anticancer agents employing essential metals such as the family of copper (II) compounds known as Casiopeinas®, with a general formula [Cu (N-N) (X-Y) H2O] NO3 where N-N is a diimine (phen or bipy) and X-Y is a bidentate ligand (acac, salal, aminoacidate, peptide, benzimidazol). These compounds have shown cytostatic, cytotoxic and antineoplastic activity in vitro and in vivo[2]. Also albumin/Casiopeinas interaction is discussed. Among those one have selected that is CasIII-ia as the most adequate to go into clinical trial Phase I. Although the mechanism of action is still not completely elucidated, experimental evidence suggests the interaction of coordination compounds with DNA (nuclear or mitochondrial) and their components and the generation of reactive oxygen species (ROS) as the main action pathways. Induction of apoptosis has been proved to be the main death tumoral cell pathway. DNA cleavage capacity, compared with the 4, 4´-diimine analogs, then is suggested an intercalation process as the first step for the DNA damage. Also calculations have been done in order to modeling the interaction between Casiopeinas and DNA [3, 4]. The clinical protocol phase I of the dimethyl bpy derivative with acac Cas IIIia is presented and the selection criteria of the drug. [1] S. H. van Rijt, P. J. Sadler, Drug Discov. Today, 14 (2009) 1089-1097. [2] L. Ruiz-Azuara, M.E. Bravo-Gomez, Curr. Med. Chem., 17 (2010) 3606-3615. [3] R. Galindo-Murillo, J. Hernandez-Lima, M. Gonzalez-Rendon, F. Cortes-Guzman, L. Ruiz-Azuara, R. Moreno-Esparza Phys. Chem. Chem. Phys., 13 (2011) 14511-14516. [4] R. Galindo-Murillo, L. Ruiz-Azuara, R. Moreno-Esparza, F. Cortes-Guzman Phys. Chem. Chem. Phys., 14 (2012) 15539-15546. Citation Format: Lena Ruiz-Azuara, Gerard Bastian, Maria Elena Bravo-Gomez, Roberto Carlos Canas, Marcos Flores-Alamo, Ines Fuentes, Carmen Mejia, Juan Carlos Garcia-Ramos, Alberto Serrano. Phase I study of one mixed chelates copper(II) compound, Casiopeina CasIIIia with antitumor activity and its mechanism of action. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr CT408. doi:10.1158/1538-7445.AM2014-CT408

Cytotoxic, Genotoxic, and Polymorphism Effects on Vanilla planifolia Jacks ex Andrews after Long-Term Exposure to Argovit® Silver Nanoparticles

Worldwide demands of Vanilla planifolia lead to finding new options to produce large-scale and contaminant-free crops. Particularly, the Mexican Government has classified Vanilla planifolia at risk and it subject to protection programs since wild species are in danger of extinction and no more than 30 clones have been found. Nanotechnology could help to solve both demands and genetic variability, but toxicological concerns must be solved. In this work, we present the first study of the cytotoxic and genotoxic effects promoted by AgNPs in Vanilla planifolia plantlets after a very long exposure time of six weeks. Our results show that Vanilla planifolia plantlets growth with doses of 25 and 50 mg/L is favored with a small decrease in the mitotic index. A dose-dependency in the frequency of cells with chromosomal aberrations and micronuclei was found. However, genotoxic effects could be considered as minimum due to with the highest concentration employed (200 mg/L), the total percentage of chromatic aberrations is lower than 5% with only three micronuclei in 3000 cells, despite the long-time exposure to AgNP. Therefore, 25 and 50 mg/L (1.5 and 3 mg/L of metallic silver) were identified as safe concentrations for Vanilla planifolia growth on in vitro conditions. Exposure of plantlets to AgNPs increase the polymorphism registered by inter-simple sequence repeat method (ISSR), which could be useful to promote the genetic variability of this species.

Polycyclic ferrocenyl(dihydro)thiazepine derivatives: Diastereo-selective synthesis, characterization, electrochemical behavior, theoretical and biological investigation

The reaction of E-2-ferrocenylmethylidenetetralones and E,E-2,6-bis-(ferrocenylmethylidene)-cyclohexanone with 2-aminothiophenol proceed with high diastereoselectivity, forming the ~4.5:1 mixture of trans- and cis-isomers of polycyclic ferrocenylthiazepines, respectively. The reactions of E,E-2,5-bis-(ferrocenylmethylidene)cyclopentanone and E,E-3,5-bis-(ferrocenylmethylidene)-1-methyl-4-piperidone with 2-aminothiophenol take place stereo specifically to form the diastereomeric tricyclic thiazepines of cis- and trans-configuration, respectively. The structures of the obtained compounds were established by IR, 1H and 13C NMR spectroscopy and mass-spectrometry. The structures of the trans-tetralino[1,2a]-, trans-5,7-dimethyltetralino[1,2a]-2-ferrocenyl [1,5]benzo-2,3-dihydrothiazepines and cis-5-ferrocenyl-methylidenecyclopentano[1,2a]-2-ferrocenyl- [1,5]benzo-2,3-dihydrothiazepine were confirmed by X-ray diffraction analysis. An electrochemical study reveals that the diferrocenyl derivatives belong to a Class I compounds of the Robin-Day classification. This behavior is explained by the analysis of frontier orbitals as calculated by density functional theory, showing that only one ferrocenyl unit participates in the generation of HOMO and LUMO orbitals. Compounds 4a and 4c showed similar capacity to inhibit the proliferation of HM1: IMSS trophozoite cultures than the first choice drug for human amoebiasis treatment, metronidazole. Morphological changes induced in the trophozoites after drug exposure suggest a redox in balance as the probable mechanism of the parasite death.

Effect of tunable redox behavior of bis chelate substituted 1,10-phenantroline Cu(II) complexes on its reaction with superoxide anion in DMSO. Toward a simple criterion to identify a SOD-like mechanism

In this work we report a series of Cu(II) complexes [Cu(N-N)2(X)]+, (N-N=substituted 1,10-phenanthroline derivatives and X=Cl- or NO3-), with tunable E1/2 for electrochemical reduction [CuII(N-N)2(X)]++1e-⇌[CuI(N-N)2]+X-. The disproportion of O2•- was explored in presence of the electro-generated species [CuI(N-N)2]+ using cyclic voltammetry in a non-aqueous media, arising a new simple method to propose a SOD-like mechanism, which can be used as a quick guide test for a compound, before being proven in biological assays. It was found that complexes with high negative half wave potential values (E1/2) for Cu(II)/Cu(I) couple shown a current increment for oxygen reduction, related to the capability of the disproportion of this reactive oxygen species.

Intercalation process of anticancer copper (II) complexes in DNA

Ternary Copper (II) Complexes (TCC) have shown cytotoxic, genotoxic, and antineoplastic activity in vitro and in vivo. There are evidences that these compounds interact directly with DNA but it is not clear how deep TCC penetrates into the DNA double helix and their specific interactions have not been established. Recently, our group found that the deoxyribose-phosphate group is the specific recognition site of TCC in DNA. Here we report a crystallographic and theoretical study to determine each step of intercalation process of TCC in DNA with the recognition site as starting point. On the basis of crystal structures, Molecular Dynamics, DFT calculations and Electron Density Analysis we found that the family of analyzed TCC prefers the sequence Thymine-Adenine-Thymine to start the insertion. The intercalation process consists of an opening of a base pair as the complex intercalates within a succession of axial ligand exchange. The copper center migrates from phosphate to ribose then to thymine and finally to adenine. It is possible that the biological activity of TCC is related to its capability to evert base pairs and perform the necessary migrations from the recognition site to the complete intercalation