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Studies of drug-cell interactions in cancer model systems are essential in the preclinical stage of rational drug design, which relies on a thorough understanding of the mechanisms underlying cytotoxic activity and biological effects, at a molecular level. This study aimed at applying complementary vibrational spectroscopy methods to evaluate the cellular impact of two Pt(ii) and Pd(ii) dinuclear chelates with spermine (Pt2Spm and Pd2Spm), using cisplatin (cis-Pt(NH3)2Cl2) as a reference compound. Their effects on cellular metabolism were monitored in a human triple-negative metastatic breast cancer cell line (MDA-MB-231) by Raman and synchrotron-radiation infrared microspectroscopies, for different drug concentrations (2-8 μM) at 48 h exposure. Multivariate data analysis was applied (unsupervised PCA), unveiling drug- and concentration-dependent effects: apart from discrimination between control and drug-treated cells, a clear separation was obtained for the different agents studied - mononuclear vs. polynuclear, and Pt(ii) vs. Pd(ii). Spectral biomarkers of drug action were identified, as well as the cellular response to the chemotherapeutic insult. The main effect of the tested compounds was found to be on DNA, lipids and proteins, the Pd(ii) agent having a more significant impact on proteins while its Pt(ii) homologue affected the cellular lipid content at lower concentrations, which suggests the occurrence of distinct and unconventional pathways of cytotoxicity for these dinuclear polyamine complexes. Raman and FTIR microspectroscopies were confirmed as powerful non-invasive techniques to obtain unique spectral signatures of the biochemical impact and physiological reaction of cells to anticancer agents.

The interaction of the widely used anticancer drug cisplatin with DNA bases was studied by EXAFS and vibrational spectroscopy (FTIR, Raman and INS), coupled with DFT/plane-wave calculations. Detailed information was obtained on the local atomic structure around the Pt(ii) centre, both in the cisplatin-purine (adenine and guanine) and cisplatin-glutathione adducts. Simultaneous neutron and Raman scattering experiments allowed us to obtain a reliable and definite picture of this cisplatin interplay with its main pharmacological target (DNA), at the molecular level. The vibrational experimental spectra were fully assigned in the light of the calculated pattern for the most favoured geometry of each drug-purine adduct, and cisplatin's preference for guanine (G) relative to adenine (A) within the DNA double helix was experimentally verified: a complete N by S substitution in the metal coordination sphere was only observed for [cDDP-A2], reflecting a somewhat weaker Pt-A binding relative to Pt-G. The role of glutathione on the drug's pharmacokinetics, as well as on the stability of platinated DNA adducts, was evaluated as this is the basis for glutathione-mediated intracellular drug scavenging and in vivo resistance to Pt-based anticancer drugs. Spectroscopic evidence of the metal's preference for glutathione's sulfur over purine's nitrogen binding sites was gathered, at least two sulfur atoms being detected in platinum's first coordination sphere.

This study reports a combined experimental and theoretical study of the solid-state polymorphism of the anticancer agent cisplatin. A complete assignment was performed for the inelastic neutron scattering (INS) and Raman spectra collected simultaneously for cisplatin, at different temperatures, with a view to obtain reliable and definitive evidence of the relative thermal stability of its α and β polymorphic species. A marked temperature-dependent hysteresis was observed, as previously reported in the literature. Theoretical calculations were carried out at the density functional theory level, using a plane-wave basis set approach and pseudopotentials. A detailed comparison with the experimental Raman and INS data showed that the α polymorph is present at the lowest temperatures, whereas the β form occurs near room temperature. Furthermore, regions of coexistence of both forms are identified, which depend on the working mode (heating or cooling). These findings imply that Raman spectroscopy allows clear identification of the α and β polymorphs at a given temperature and can unambiguously discriminate between them. Elucidation of the polymorphic equilibrium of this widely used anticancer drug is paramount for its pharmaceutical preparation and storage conditions.

The well-known platinum(II) chemotherapeutic drugs cisplatin [cis-(NH(3))(2)PtCl(2)] and carboplatin [Pt(NH(3))(2)C(6)O(4)H(6)], as well as the analogous transplatin [trans-(NH(3))(2)PtCl(2)], were studied by inelastic neutron scattering (INS) spectroscopy, coupled to quantum mechanical methods, and some ancillary work with X-ray diffraction on powders. An assignment of the experimental spectra was carried out based on the calculated INS transition frequencies and intensities (at the DFT level), thereby achieving a good correspondence between the calculated and observed data. Unusually good-quality INS spectra were obtained from about 250 mg, which is the smallest sample of a hydrogenous compound for which a successful INS interpretation has been reported. The knowledge of the local configuration of this kind of complexes is essential for an accurate understanding of their activity, which will pave the way for the rational design of novel third-generation drugs comprising cisplatin- and carboplatin-like moieties., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A conformational and vibrational analysis of cis-diamminedichloropalladium(ii) (cDDPd) is reported. Several theoretical methods (from Hartree-Fock to Møller-Plesset and Density Functional Theory) combined with different all-electron basis-sets are evaluated, in view of determining the best suited strategy for accurately representing this molecule. This choice is based on the best compromise between accuracy and computational requirements. Different scaling models were tested for obtaining the best scaling schemes of the vibrational modes to be used in this type of inorganic systems. The structural parameters and vibrational results predicted by the calculations are compared with the corresponding experimental data, namely X-ray structure and vibrational spectra. Finally, a complete assignment of the cDDPd vibrational spectra is presented.

In the light of the recognized anticancer properties of cisplatin-type inorganic systems, the exact knowledge of their conformational preferences is of the utmost importance for understanding their biological activity. The present study reports the use of theoretical (quantum mechanical) calculations for achieving this goal. An alternative calculation method to the use of the AE basis sets, both accurate and computationally feasible, was presently tested for the conformational and vibrational study of cis-diamminedichloroplatinum(II). Effective core potentials (ECPs) were used, within the HF methodology and, within the B3LYP and mPW1PW DFT protocols. The DFT methods (particularly mPW1PW) were found to be the best choice for describing cDDP (as compared to the HF methodology).

A conformational and vibrational analysis of cisplatin [cis-diamminedichloro-platinum(II)] (cDDP) is reported. Several theory methods (from Hartree-Fock to Moller-Plesset and density functional theory) combined with different all-electron basis sets are evaluated, in view of determining the best suited strategy for accurately representing this molecule. This choice is based on the best compromise between accuracy and computational requirements. Different scaling models of the cDDP vibrational modes were tested for obtaining the best scaling factors to be used in this type of inorganic systems. The structural parameters and vibrational results predicted by the calculations are compared with the corresponding experimental data, namely, x-ray structure, and Raman and inelastic neutron scattering spectra. Finally, a complete assignment of the cDDP vibrational spectra is presented.