Exploring the Antitumor Potential of Copper Complexes Based on Ester Derivatives of Bis(pyrazol-1-yl)acetate Ligands

Bis(pyrazol-1-yl)acetic acid (HC(pz)(2)COOH) and bis(3,5-dimethyl-pyrazol-1-yl)acetic acid (HC(pz(Me2))(2)COOH) were converted into the methyl ester derivatives 1 (L-OMe) and 2 (L-2OMe), respectively, and were used for the preparation of Cu(I) and Cu(II) complexes 3-10. The copper(II) complexes were prepared by the reaction of CuCl2 center dot 2H(2)O or CuBr2 with ligands 1 and 2 in methanol solution. The copper(I) complexes were prepared by the reaction of Cu[(CH3CN)(4)]PF6 and 1,3,5-triaza-7-phosphaadamantane (PTA) or triphenylphosphine with L-OMe and L-2OMe in acetonitrile solution. Synchrotron radiation-based complementary techniques (XPS, NEXAFS, and XAS) were used to investigate the electronic and molecular structures of the complexes and the local structure around copper ions in selected Cu(I) and Cu(II) coordination compounds. All Cu(I) and Cu(II) complexes showed a significant in vitro antitumor activity, proving to be more effective than the reference drug cisplatin in a panel of human cancer cell lines, and were able to overcome cisplatin resistance. Noticeably, Cu complexes appeared much more effective than cisplatin in 3D spheroid cultures. Mechanistic studies revealed that the antitumor potential did not correlate with cellular accumulation but was consistent with intracellular targeting of PDI, ER stress, and paraptotic cell death induction

Molecular analysis of hepatitis B virus (HBV) in an HIV co-infected patient with reactivation of occult HBV infection following discontinuation of lamivudine-including antiretroviral therapy

Abstract Background Occult hepatitis B virus (HBV) infection (OBI) is characterized by HBV DNA persistence even though the pattern of serological markers indicates an otherwise resolved HBV infection. Although OBI is usually clinically silent, immunocompromised patients may experience reactivation of the liver disease. Case presentation We report the case of an individual with human immunodeficiency virus (HIV) infection and anti-HBV core antibody positivity, who experienced severe HBV reactivation after discontinuation of lamivudine-including antiretroviral therapy (ART). HBV sequencing analysis showed a hepatitis B surface antigen escape mutant whose presence in an earlier sample excluded reinfection. Molecular sequencing showed some differences between two isolates collected at a 9-year interval, indicating HBV evolution. Resumption of ART containing an emtricitabine/tenofovir combination allowed control of plasma HBV DNA, which fell to undetectable levels. Conclusion This case stresses the ability of HBV to evolve continuously, even during occult infection, and the effectiveness of ART in controlling OBI reactivation in HIV-infected individuals.</p

A Prognostic Model for Estimating the Time to Virologic Failure in HIV-1 Infected Patients Undergoing a New Combination Antiretroviral Therapy Regimen

<p>Abstract</p> <p>Background</p> <p>HIV-1 genotypic susceptibility scores (GSSs) were proven to be significant prognostic factors of fixed time-point virologic outcomes after combination antiretroviral therapy (cART) switch/initiation. However, their relative-hazard for the time to virologic failure has not been thoroughly investigated, and an expert system that is able to predict how long a new cART regimen will remain effective has never been designed.</p> <p>Methods</p> <p>We analyzed patients of the Italian ARCA cohort starting a new cART from 1999 onwards either after virologic failure or as treatment-naïve. The time to virologic failure was the endpoint, from the 90^thday after treatment start, defined as the first HIV-1 RNA > 400 copies/ml, censoring at last available HIV-1 RNA before treatment discontinuation. We assessed the relative hazard/importance of GSSs according to distinct interpretation systems (Rega, ANRS and HIVdb) and other covariates by means of Cox regression and random survival forests (RSF). Prediction models were validated via the bootstrap and c-index measure.</p> <p>Results</p> <p>The dataset included 2337 regimens from 2182 patients, of which 733 were previously treatment-naïve. We observed 1067 virologic failures over 2820 persons-years. Multivariable analysis revealed that low GSSs of cART were independently associated with the hazard of a virologic failure, along with several other covariates. Evaluation of predictive performance yielded a modest ability of the Cox regression to predict the virologic endpoint (c-index≈0.70), while RSF showed a better performance (c-index≈0.73, p < 0.0001 vs. Cox regression). Variable importance according to RSF was concordant with the Cox hazards.</p> <p>Conclusions</p> <p>GSSs of cART and several other covariates were investigated using linear and non-linear survival analysis. RSF models are a promising approach for the development of a reliable system that predicts time to virologic failure better than Cox regression. Such models might represent a significant improvement over the current methods for monitoring and optimization of cART.</p

New Cu(I) Complexes of Bis(pyrazol-1-yl)acetate Ligands Functionalized with an NMDA Receptor Antagonist with Cytotoxic Activity

Among transition metals, copper is one of the most versatile elements to obtain metal-based drugs, due to the wide structural variability, biologically accessible redox properties and bioavailability. In the attempt to find potential Cu-based antitumor agents, our efforts have been recently focused on the design and synthesis of copper compounds of bis(azolyl)acetate heteroscorpionate ligands of general formula [(az)2CH(COOH)], where az = pyrazole, 3,5-dimethylpyrazole and 1,2,4-triazole. Cu(I) compounds have been synthesized employing bis(pyrazol-1-yl)acetic acid (LH), bis(3,5-dimethylpyrazol-1-yl)acetic acid (L2H) and the same ligands conjugated with the NMDA receptor antagonist (6,6-diphenyl-1,4-dioxan-2-yl)methanamine (LNMDA and L2NMDA). The selection of an NMDA antagonist for the coupling with LH and L2H has been suggested by the observation that NMDA receptors are expressed and play a role in several types of cancer models. Phospanes as coligands (triphenylphosphine, PPh3, and 1,3,5-triaza-7-phosphaadamantane, PTA) have also been used in order to stabilize the Cu(I) centre in the +1 oxidation state. All the new complexes have showed a significant antitumor activity on a panel of human tumor cell lines of different histology, with cisplatin-sensitive, cisplatin-resistant or multi-drug-resistant phenotype. Their half maximal inhibitory concentration (IC50) values have been in the low- and sub-micromolar range and, in general, significantly lower than that of cisplatin. Interestingly, the fact that all the complexes have proved to be significantly more active than cisplatin even in three-dimensional (3D) spheroids of H157 and BxPC3 cancer cells has increased the relevance of the in vitro results

Water soluble coinage metal N-Heterocyclic Carbene complexes: synthesis and anticancer studies

N-heterocyclic carbenes (NHCs) are an interesting class of ligands with donor properties similar to phosphanes. Their chemical versatility not only implies a wide variety of structural diversity and coordination modes, but also a capability to form stable complexes with a large number of transition metals with different oxidation states. In particular, NHC complexes of coinage metals have recently showed to be good candidates as an alternative to cisplatin, exhibiting encouraging results in the field of anticancer drugs research. In the last years, we have developed several classes of coinage metal-NHC complexes obtained from the precursors {[HB(HImR)3]Br2} (R = Bn, Mes and t-Bu), {H2C(HTzR)2} and {H2C(HImR)2} (R = (CH2)3SO3 - or (CH2)2COO-). Recently we have focused the research work on 11th group metal-NHCs complexes obtained from hydrosoluble 1,3-symmetrically and 1,3-unsymmetrically substituted NHCs precursors based on imidazole and benzimidazole scaffolds. More recently we have synthesized and investigated the cytotoxic activity of the novel NHC ligand precursor [HTz(pNO2Bn)2]Br, and the corresponding metal complexes M[Tz(pNO2Bn)2]Br (M = Cu(I), Ag(I) or Au(I)). In addition, novel water-soluble bis(NHCSO3)CuCl complexes (NHCSO3 = HImBn,PrSO3, Na(4-Me)ImPrSO3 and NaBzimPrSO3), derived by the sulfonated N-heterocyclic carbene precursors HImBn,PrSO3 (3-(1-benzyl-1H-imidazol-3-ium-3-yl)propane-1-sulfonate), Na(4-Me)HImPrSO3 (sodium 3,3'-(4-methyl-1Himidazole- 3-ium-1,3-diyl)dipropane-1-sulfonate) and NaHBzimPrSO3 (sodium 3,3'-(1H-benzo[d]imidazole-3- ium-1,3-diyl)dipropane-1-sulfonate), have been synthesized. The in vitro antitumor effects of the complexes and the corresponding free ligands were evaluated on a panel of various human tumour cell lines. Their cytotoxic properties were also evaluated against non-transformed human cells and on a cellular model of cisplatin-resistance

Syntheses and Reactivity of New Zwitterionic Imidazolium Trihydridoborate and Triphenylborate Species

In this study, four new N-(alkyl/aryl)imidazolium-borates were prepared, and their deprotonation reactions were investigated. Addition of BH3•THF to N-benzylimidazoles and N-mesitylimidazoles leads to imidazolium-trihydridoborate adducts. Ammonium tetraphenylborate reacts with benzyl- or mesityl-imidazoles with the loss of one of the phenyl groups yielding the corresponding imidazolium-triphenylborates. Their authenticity was confirmed by CHN analysis, 1H-NMR, 13C-NMR, 11B-NMR, FT-IR spectroscopy, and electrospray ionization mass spectrometry (ESI-MS). 3-Benzyl-imidazolium-1-yl)trihydridoborate, (HImBn)BH3, and (3-mesityl-imidazolium-1-yl)trihydridoborate, (HImMes)BH3, were also characterized by X-ray crystallography. The reactivity of these new compounds as carbene precursors in an effort to obtain borate-NHC complexes was investigated and a new carbene-borate adduct (which dimerizes) was obtained via a microwave-assisted procedure

Syntheses and Biological Studies of Cu(II) Complexes Bearing Bis(pyrazol-1-yl)- and Bis(triazol-1-yl)-acetato Heteroscorpionate Ligands

Copper(II) complexes of bis(pyrazol-1-yl)- and bis(triazol-1-yl)-acetate heteroscorpionate ligands have been synthesized. The copper(II) complexes [HC(COOH)(pzMe2)2]Cu[HC(COO)(pzMe2)2]&#183;ClO4, [HC(COOH)(pz)2]2Cu(ClO4)2 (pzMe2 = 3,5-dimethylpyrazole; pz = pyrazole) were prepared by the reaction of Cu(ClO4)2&#183;6H2O with bis(3,5-dimethylpyrazol-1-yl)acetic acid (HC(COOH)(pzMe2)2) and bis(pyrazol-1-yl)acetic acid (HC(COOH)(pz)2) ligands in ethanol solution. The copper(II) complex [HC(COOH)(tz)2]2Cu(ClO4)2&#183;CH3OH (tz = 1,2,4-triazole) was prepared by the reaction of Cu(ClO4)2&#183;6H2O with bis(1,2,4-triazol-1-yl)acetic acid (HC(COOH)(tz)2) ligand in methanol solution. The synthesized Cu(II) complexes, as well as the corresponding uncoordinated ligands, were evaluated for their cytotoxic activity in monolayer and 3D spheroid cancer cell cultures with different Pt(II)-sensitivity. The results showed that [HC(COOH)(pzMe2)2]Cu[HC(COO)(pzMe2)2]&#183;ClO4 was active against cancer cell lines derived from solid tumors at low IC50 and this effect was retained in the spheroid model. Structure and ultra-structure changes of treated cancer cells analyzed by Transmission Electron Microscopy (TEM) highlighted the induction of a cytoplasmic vacuolization, thus suggesting paraptotic-like cancer cell death triggering

Design, Synthesis and Reactivity of New Zwitterionic Imidazolium-based Species

N-Heterocyclic Carbenes (NHCs) are an interesting family of ligands with donor properties comparable to phosphane ones. They can form complexes with transition elements and, among them, the coinage metals belonging to the 11th group of the periodic table. Metal-NHCs compounds have obtained a lot of interest in the last years because of their potential applications in catalysis, carbene transfer reactions and medicinal inorganic chemistry. In this study, the rational design and synthesis of novel N-(alkyl/aryl)imidazolium-borates compounds and the corresponding reactions towards the deprotonation have been studied. The imidazolium-trihydridoborate adducts have been obtained by the addition of BH3·THF to the starting materials N-benzyl- or N-mesityl-imidazole. The related imidazolium-triphenylborate species have been prepared by the reaction of ammonium tetraphenylborate with benzylimidazole or mesitylimidazole with the loss of one of the phenyl groups. All these new species have been fully characterized, both analytically and spectroscopically, to confirm their structures by means of CHN elemental analysis, 1H-NMR, 13C-NMR, 11B-NMR, FT-IR spectroscopy and electrospray ionization mass spectrometry (ESI-MS). Regarding the compounds (3-benzylimidazolium-1-yl)trihydridoborate, (HImBn)BH3, and (3-mesitylimidazolium-1-yl)trihydridoborate, (HImMes)BH3, single crystals suitable for the X-ray diffraction crystallography have been obtained by slow evaporation of CHCl3 and CHCl3/THF solutions, respectively. The reactivity of all novel compounds as carbene precursors has been evaluated with the aim to produce borate-NHC complexes and a new carbene-borate species has been synthesized via a microwaves-assisted method