Mauro Ravera
University of Turin
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Featured researches published by Mauro Ravera.
Journal of Organometallic Chemistry | 1995
Domenico Osella; Luciano Milone; Carlo Nervi; Mauro Ravera
Abstract A simple electrochemical criterion is employed for an approximate evaluation of the electronic interaction between redox centres in π-conjugated organometallic dimers. This approach allows one to predict the results of the use of such organometallic complexes (and related polymers) as precursors of mixed-valence compounds (in solution) and low-dimensional conducting or non-linear optical materials (in the solid state). Chemical complications following the redox processes often alter the electrochemical response. In such cases, this approach is only useful if the experimental conditions (measurements at high scan rates or sub-ambient temperatures) are chosen carefully.
Metallomics | 2012
Luca Gaviglio; Annika Gross; Nils Metzler-Nolte; Mauro Ravera
The synthesis and characterization of four Pt(IV)-peptide conjugates, containing one or two peptides in the axial position, designed for the purpose of targeted drug delivery to tumor cells, are described. The precursor cis,cis,trans-diamminedichloridodisuccinatoplatinum(IV) was coupled in the last step of standard solid-phase peptide synthesis (SSPS) with an analogue of neurotensin (pseudo-neurotensin = Lys-Lys-Pro-Tyr-Ile-Leu) and with octreotate (D-Phe-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-OH), an analogue of somatostatin, respectively. For all peptides, the SSPS reactions afforded both mono- and diconjugated Pt-peptide species, which were separated and purified by RP-HPLC. The two couples of conjugates, together with the precursor, were tested as cytotoxic agents towards different cancer cell lines. In general all conjugates are good inhibitors of cellular proliferation when compared to a nontargeting platinum(IV) parent compound, so that its relatively low cytotoxicity is greatly improved by addition of the peptides.
Journal of Medicinal Chemistry | 2012
Nicola Margiotta; Cristina Marzano; Valentina Gandin; Domenico Osella; Mauro Ravera; Elisabetta Gabano; James Alexis Platts; Emanuele Petruzzella; James D. Hoeschele; Giovanni Natile
Although the encouraging antitumor activity of [PtCl(2)(cis-1,4-DACH)] (1; DACH = diaminocyclohexane) was shown in early studies almost 20 years ago, the compound has remained nearly neglected. In contrast, oxaliplatin, containing the isomeric 1(R),2(R)-DACH carrier ligand, enjoys worldwide clinic application as a most important therapeutic agent in the treatment of colorectal cancer. By extending the investigation to human chemotherapy-resistant cancer cells, we have demonstrated the real effectiveness of 1 in circumventing cisplatin and oxaliplatin resistance in LoVo colon cancer cells. The uptake of compound 1 by the latter cells was similar to that of sensitive LoVo cells. This is not the case for all other compounds considered in this investigation. Interaction with double-stranded DNA, investigated by a biosensor assay and by quantum mechanical/molecular mechanical geometry optimization of the 1,2-GG intrastrand cross-link, does not show significant differences between 1 and oxaliplatin. However, the DNA adducts of 1 are removed from repair systems with lower efficiency and are more effective in inhibiting DNA and RNA polymerase.
Biometals | 2006
Marco Mascini; Graziana Bagni; Maria Letizia Di Pietro; Mauro Ravera; Sara Baracco; Domenico Osella
Electrochemical techniques were used to study the interaction between a panel of antiproliferative metallo-drugs and double-stranded DNA immobilized on screen-printed electrodes as a model of the analogous interaction occurring in solution. The propensity of a given metal drug to interact with DNA was measured as a function of the decrease of guanine oxidation signal, which was detected by square wave voltammetry. Estimates of variations in experimental parameters, such as the concentration of complexes, time following dissolution (ageing time) and the presence of chloride, are provided.
Inorganic Chemistry Communications | 1998
Domenico Osella; Roberto Gobetto; Carlo Nervi; Mauro Ravera; Rosaria D'Amato; Maria Vittoria Russo
Abstract We describe herein the synthesis and the electrochemical behaviour of a series of bis(ferrocenylethynyl) complexes of platinum(II). In all complexes, the electronic interaction between the redox-active iron cores of the ferrocenyl termini is small, indicating a moderate electronic delocalisation over the bis(cyclopentadienyl-acetylide)Pt chain.
Journal of Biological Inorganic Chemistry | 2011
James Alexis Platts; Giuseppe Ermondi; Giulia Caron; Mauro Ravera; Elisabetta Gabano; Luca Gaviglio; Georgio Pelosi; Domenico Osella
We report the results of the quantitative structure–property relationship analysis of 31 Pt(IV) complexes, for three of which the synthesis is reported for the first time. The X-ray structural analysis of one complex of the series was performed to demonstrate that the PM6 semiempirical method satisfactorily reproduces key features of the geometry of the complexes investigated. Molecular properties extracted from such calculations were then used to construct models of experimental data such as electrochemical peak potentials (evaluated by cyclic voltammetry) and the octanol–water partition coefficient (evaluated by a reversed-phase high performance liquid chromatography method), which are key aspects in the design of such Pt(IV) complexes as potential anticancer prodrugs. Statistically accurate models for both properties were found using combinations of surface areas, orbital energies, dipole moments, and atomic partial charges. These models could form the basis of virtual screening of potential drug molecules, allowing the prediction of properties, closely related to the antiproliferative activity of Pt(IV) complexes, directly from calculated data.
Inorganica Chimica Acta | 1996
Noel W. Duffy; John McAdam; Carlo Nervi; Domenico Osella; Mauro Ravera; Brian H. Robinson; Jim Simpson
Abstract Electrochemical criteria are used to evaluate the electronic interaction between redox centres in the π-conjugated diyne complexes {RCC[Co 2 (CO) 6 ]CC[Co 2 (CO) 6 ]R} and {RCC[Co 2 (CO) 6 ](S)C[Co 2 (CO) 6 ]} (RPh, Fc) where the aromatic spacer S is phenyl, napthalene or anthracene. Voltammetry at microelectrode, differential pulse techniques and low temperature measurements are used to obviate the chemical complications following the primary redox process. A mechanism is proposed which successfully simulates the electrochemical data.
Chemosphere | 2009
Mauro Ravera; Alessandra Buico; Fabio Gosetti; Claudio Cassino; Davide Musso; Domenico Osella
Sulfonated aromatic pollutants such as Armstrongs acid, or 1,5-naphthalenedisulfonic acid (NDS), are recalcitrant to environmental breakdown and microbial treatment. This study investigated the effects of H(2)O(2) concentration, pH, microwave (MW) power and irradiation time on the oxidative degradation of NDS in aqueous solutions. The formation of hydroxyl radicals as the active oxidant was confirmed by electron paramagnetic resonance spin trapping. A combination of both H(2)O(2) and MW heating proved essential for NDS degradation. Degradation factors of f70% were obtained after about 20min of irradiation at [H(2)O(2)]:[NDS] ratios=10. Acidic conditions were found to be more favorable to the degradation of NDS, and the process follows pseudo-first-order kinetics. Attempts to scale-up the process using a conventional MW reactor provided less striking results.
Journal of Inorganic Biochemistry | 2013
Manuela Alessio; Ilaria Zanellato; Ilaria Bonarrigo; Elisabetta Gabano; Mauro Ravera; Domenico Osella
The bifunctional Pt(IV) conjugate cis,cis,trans-diamminedichloridobis(valproato)platinum(IV), based on the cisplatin square-plane with two axial valproato (2-propylpentanoate, VPA) ligands, has been re-synthesized with a modified procedure and its biological activity was compared with that of its isomer cis,cis,trans-diamminedichloridobis(n-octanoato)platinum(IV). Both complexes showed a striking cytotoxic effect (in the micro or sub-micromolar range) on various human carcinoma cell lines (namely ovarian, colon, breast and lung cancer), and, in particular, on cells derived from malignant pleural mesothelioma. This remarkable activity is due to the action of the cisplatin metabolite only, generated by the intracellular Pt(IV)→Pt(II) reduction, which concentration is greatly increased by the enhanced cellular accumulation of the original, highly lipophilic Pt(IV)-bis(carboxylato) complexes. The two axial VPA ligands are released in a too low concentration to act as histone deacetylase inhibitor (HDACI), as VPA works in the millimolar range, so that no synergism can be claimed. Moreover, n-octanoic acid is substantially deprived of any HDACI propensity.
Inorganica Chimica Acta | 1993
Domenico Osella; O. Gambino; Carlo Nevi; Mauro Ravera; Davide Bertolino
An electrochemical study on the electronic interactions occurring between the two ‘CCo3(CO)9’ redox cores in the dimers Co3(CO)9(CC)Co3(CO)9 and Co3(CO)9(CCCC)Co3(CO)9 is reported. In both derivatives, two well resolved peaks/waves are observed in several solvents by cyclic, square wave voltammetry and d.c. polarography, respectively, for the (0,0)/(0,1−) and (0,1−)/(1−,1−) reduction processes. The differences in electrode potentials of the two first reductions, ΔE°′, indicate a moderate electronic interaction between the redox centres in both compounds, which mainly occurs via the carbon chains.