Ruthenium(III) complexes are promising anticancer metallodrugs because of their antimetastatic (migrastatic) potential and significantly lower host toxicity than generally used platinum metallodrugs. On the other hand, the ruthenium(III) complexes generally show low solubility and stability in an aqueous environment but exhibit some toxicity associated with unspecific delivery. For these reasons, numerous ongoing studies deal with their encapsulation into various delivery systems to maximize their therapeutic efficacy. One of these systems can also be crystals of nontoxic metal-organic frameworks (MOFs). In this work, we studied incorporation of a bioactive ruthenium(III) complex (RuC) inside MOFs derived from γ-cyclodextrin (γ-CD) and biocompatible potassium ions, forming CD-MOF-1. Viability studies in vitro were carried out using spheroids of human hepatoblastoma cell line HepG2. These studies revealed that the RuC-CD-MOF-1 system provides effective cancer cell suppression through slow gradual release over a longer period (>10 days) while reducing acute cytotoxic effects associated with naked RuC. This combination was defined for further development and optimization as a drug-delivery platform for metallodrugs.

• MeSH
• buňky Hep G2 MeSH
• cyklodextriny * chemie   MeSH
• gama-cyklodextriny * chemie   MeSH
• komplexní sloučeniny * chemie   farmakologie   chemická syntéza   MeSH
• lidé MeSH
• molekulární struktura MeSH
• porézní koordinační polymery * chemie   farmakologie   chemická syntéza   MeSH
• proliferace buněk účinky léků   MeSH
• protinádorové látky * farmakologie   chemie   chemická syntéza   MeSH
• ruthenium * chemie   farmakologie   MeSH
• screeningové testy protinádorových léčiv MeSH
• viabilita buněk účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• cyklodextriny * MeSH
• gama-cyklodextriny * MeSH
• komplexní sloučeniny * MeSH
• porézní koordinační polymery * MeSH
• protinádorové látky * MeSH
• ruthenium * MeSH

ConspectusMagnetic resonance techniques represent a fundamental class of spectroscopic methods used in physics, chemistry, biology, and medicine. Electron paramagnetic resonance (EPR) is an extremely powerful technique for characterizing systems with an open-shell electronic nature, whereas nuclear magnetic resonance (NMR) has traditionally been used to investigate diamagnetic (closed-shell) systems. However, these two techniques are tightly connected by the electron-nucleus hyperfine interaction operating in paramagnetic (open-shell) systems. Hyperfine interaction of the nuclear spin with unpaired electron(s) induces large temperature-dependent shifts of nuclear resonance frequencies that are designated as hyperfine NMR shifts (δHF).Three fundamental physical mechanisms shape the total hyperfine interaction: Fermi-contact, paramagnetic spin-orbit, and spin-dipolar. The corresponding hyperfine NMR contributions can be interpreted in terms of through-bond and through-space effects. In this Account, we provide an elemental theory behind the hyperfine interaction and NMR shifts and describe recent progress in understanding the structural and electronic principles underlying individual hyperfine terms.The Fermi-contact (FC) mechanism reflects the propagation of electron-spin density throughout the molecule and is proportional to the spin density at the nuclear position. As the imbalance in spin density can be thought of as originating at the paramagnetic metal center and being propagated to the observed nucleus via chemical bonds, FC is an excellent indicator of the bond character. The paramagnetic spin-orbit (PSO) mechanism originates in the orbital current density generated by the spin-orbit coupling interaction at the metal center. The PSO mechanism of the ligand NMR shift then reflects the transmission of the spin polarization through bonds, similar to the FC mechanism, but it also makes a substantial through-space contribution in long-range situations. In contrast, the spin-dipolar (SD) mechanism is relatively unimportant at short-range with significant spin polarization on the spectator atom. The PSO and SD mechanisms combine at long-range to form the so-called pseudocontact shift, traditionally used as a structural and dynamics probe in paramagnetic NMR (pNMR). Note that the PSO and SD terms both contribute to the isotropic NMR shift only at the relativistic spin-orbit level of theory.We demonstrate the advantages of calculating and analyzing the NMR shifts at relativistic two- and four-component levels of theory and present analytical tools and approaches based on perturbation theory. We show that paramagnetic NMR effects can be interpreted by spin-delocalization and spin-polarization mechanisms related to chemical bond concepts of electron conjugation in π-space and hyperconjugation in σ-space in the framework of the molecular orbital (MO) theory. Further, we discuss the effects of environment (supramolecular interactions, solvent, and crystal packing) and demonstrate applications of hyperfine shifts in determining the structure of paramagnetic Ru(III) compounds and their supramolecular host-guest complexes with macrocycles.In conclusion, we provide a short overview of possible pNMR applications in the analysis of spectra and electronic structure and perspectives in this field for a general chemical audience.

• Publikační typ
• časopisecké články MeSH

Theoretical interpretation of hyperfine interactions was pioneered in the 1950s-1960s by the seminal works of McConnell, Karplus, and others for organic radicals and by Watson and Freeman for transition-metal (TM) complexes. In this work, we investigate a series of octahedral Ru(III) complexes with aromatic ligands to understand the mechanism of transmission of the spin density from the d-orbital of the metal to the s-orbitals of the ligand atoms. Spin densities and spin populations underlying ligand hyperfine couplings are analyzed in terms of π-conjugative or σ-hyperconjugative delocalization vs spin polarization based on symmetry considerations and restricted open-shell vs unrestricted wave function analysis. The transmission of spin density is shown to be most efficient in the case of symmetry-allowed π-conjugative delocalization, but when the π-conjugation is partially or fully symmetry-forbidden, it can be surpassed by σ-hyperconjugative delocalization. Despite a lower spin population of the ligand in σ-hyperconjugative transmission, the hyperfine couplings can be larger because of the direct involvement of the ligand s-orbitals in this delocalization pathway. We demonstrate a quantitative correlation between the hyperfine couplings of aromatic ligand atoms and the characteristics of the metal-ligand bond modulated by the trans substituent, a hyperfine trans effect.

• Publikační typ
• časopisecké články MeSH