Metallodrugs: Mechanisms of Action, Molecular Targets and Biological Activity

Non-Medical Applications of Inorganic Medicines. A Switch Based on Mechanistic Knowledge

Metals have been used in medicine for centuries. However, it was not until much later that the effects of inorganic drugs could be rationalized from a mechanistic point of view. Today, thanks to the technologies available, this approach has been functionally developed and implemented. It has been found that there is probably no single biological target for the pharmacological effects of most inorganic drugs. Herein, we present an overview of some integrated and multi-technique approaches to elucidate the molecular interactions underlying the biological effects of metallodrugs. On this premise, selected examples are used to illustrate how the information obtained on metal-based drugs and their respective mechanisms can become relevant for applications in fields other than medicine. For example, some well-known metallodrugs, which have been shown to bind specific amino acid residues of proteins, can be used to solve problems related to protein structure elucidation in crystallographic studies. Diruthenium tetraacetate can be used to catalyze the conversion of hydroxylamines to nitrones with a high selectivity when bound to lysozyme. Finally, a case study is presented in which an unprecedented palladium/arsenic-mediated catalytic cycle for nitrile hydration was discovered thanks to previous studies on the solution chemistry of the anticancer compound arsenoplatin-1 (AP-1).

Synchrotron nano-FTIR spectroscopy for probing anticancer drugs at subcellular scale

The cellular response to cisplatin was assessed in human osteosarcoma cells, using synchrotron-based (SR) Fourier Transform InfraRed nanospectroscopy (nano-FTIR) at the MIRIAM beamline B22 of Diamond Light Source (UK). This label-free mapping method delivered simultaneous morphological and biochemical information on a subcellular level (i.e. 100 s nanometer or better). Based on specific spectral biomarkers, the main biochemical constituents affected by the drug were identified at distinct locations within the cell´s inner body. Cisplatin was shown to have a noteworthy effect on proteins, mostly within the cytoplasm. A clear drug impact on cellular lipids was also observed. Within current literature on s-SNOM, this nanospectroscopy work represents a first successful application in life sciences providing full fingerprint nano-FTIR spectra across intact human cancer cells.

Resurgence and Repurposing of Antifungal Azoles by Transition Metal Coordination for Drug Discovery

Coordination compounds featuring one or more antifungal azole (AA) ligands constitute an interesting family of candidate molecules, given their medicinal polyvalence and the viability of drug complexation as a strategy to improve and repurpose available medications. This review reports the work performed in the field of coordination derivatives of AAs synthesized for medical purposes by discussing the corresponding publications and emphasizing the most promising compounds discovered so far. The resulting overview highlights the efficiency of AAs and their metallic species, as well as the potential still lying in this research area.

Designing a multitarget In(III) compound to overcome the resistance of lung cancer cells to cisplatin

Designing novel anticancer non-platinum metal agents is fully challenging. Herein, a series of little-known indium (In) 2-acetylpyridine thiosemicarbazone compounds as potential anticancer agents were designed, synthesized, and characterized. The hydrogen atoms at the N-4 position with the alkyl of the In compounds significantly increased cellular uptake and cytotoxicity. In(III) compounds showed significantly higher cytotoxicity toward cisplatin-resistant cell lines than cisplatin. More importantly, C4 greatly inhibited A549DDP tumor growth in a vaccinated mouse model. C4 exerted cytotoxic effects via a multitarget mechanism. First, it activated p53 and blocked the cell cycle at the S phase, which then led to weak expression levels of cyclin and related kinases and upregulation of the expression levels of cyclin-dependent kinase inhibitors. C4 also depolarized the mitochondrial membrane potential and regulated the expression of the Bcl-2 family, which then released cyt-c and activated caspase-3/8/9 to execute apoptotic pathways. Then, it inhibited telomerase through the inhibition of the expression of the c-Myc regulator gene and expression of the human telomerase reverse transcriptase. Furthermore, C4 showed excellent antimetastatic activity.