The reduction of ruthenium(III) complexes with triazolopyrimidine ligands by ascorbic acid and mechanistic insight into their action in anticancer therapy

Pyrimidines-Based Heterocyclic Compounds: Synthesis, Cytoxicity Evaluation and Molecular Docking

A variety of structurally different pyrimidines were synthesized. Elemental analysis, FT-IR, ¹H NMR, and ¹³C NMR spectroscopy were used to confirm the chemical structures of all prepared compounds. The synthesized pyrimidines were screened against the growth of five human cancer cell lines (prostate carcinoma PC3, liver carcinoma HepG-2, human colon cancer HCT-116, human breast cancer MCF-7, human lung cancer A-549), and normal human lung fibroblasts (MRC-5) using MTT assay. Most of the screened pyrimidines have anti-proliferative activity on the growth of the PC3 cell line. Compounds 3b and 3d were more potent than the reference vinblastine sulfate (~2 to 3 × fold) and they can be considered promising leads for treating prostate cancer disease. Moreover, the screened compounds 3b, 3f, 3g, 3h, and 5 were assessed according to the values of their selectivity index (SI) and were found to be more selective and safer than vinblastine sulfate. Furthermore, using in silico computational tools, the physicochemical properties of all pyrimidine ligands were assessed, and the synthesized compounds fall within the criteria of RO5, thus having the potential to be orally bioavailable.

Safety and Efficacy Evaluation In Vivo of a Cationic Nucleolipid Nanosystem for the Nanodelivery of a Ruthenium(III) Complex with Superior Anticancer Bioactivity

Simple Summary

The availability of selective, effective, and safe anticancer agents is a major challenge in the field of cancer research. As part of a multidisciplinary research project, in recent years our group has proposed an original class of nanomaterials for the delivery of new anticancer drugs based on ruthenium(III) complexes. In cellular models, these nanosystems have been shown to be effective in counteracting growth and proliferation of human breast cancer cells. Compared to conventional metallochemotherapeutics such as platinum-based agents whose clinical practice is associated with serious undesirable effects, ruthenium complexes share improved biochemical profiles making them more selective towards cancer cells and less cytotoxic to healthy cells. Their combination with biocompatible nanocarriers further enhances these promising features, as here showcased by our research carried out in an animal model which underscores the efficacy and safety in vivo of one of our most promising ruthenium-based nanosystems.

Abstract

Selectivity and efficacy towards target cancer cells, as well as biocompatibility, are current challenges of advanced chemotherapy powering the discovery of unconventional metal-based drugs and the search for novel therapeutic approaches. Among second-generation metal-based chemotherapeutics, ruthenium complexes have demonstrated promising anticancer activity coupled to minimal toxicity profiles and peculiar biochemical features. In this context, our research group has recently focused on a bioactive Ru(III) complex—named AziRu—incorporated into a suite of ad hoc designed nucleolipid nanosystems to ensure its chemical stability and delivery. Indeed, we proved that the structure and properties of decorated nucleolipids can have a major impact on the anticancer activity of the ruthenium core. Moving in this direction, here we describe a preclinical study performed by a mouse xenograft model of human breast cancer to establish safety and efficacy in vivo of a cationic Ru(III)-based nucleolipid formulation, named HoThyRu/DOTAP, endowed with superior antiproliferative activity. The results show a remarkable reduction in tumour with no evidence of animal suffering. Blood diagnostics, as well as biochemical analysis in both acute and chronic treated animal groups, demonstrate a good tolerability profile at the therapeutic regimen, with 100% of mice survival and no indication of toxicity. In addition, ruthenium plasma concentration analysis and tissue bioaccumulation were determined via appropriate sampling and ICP-MS analysis. Overall, this study supports both the efficacy of our Ru-containing nanosystem versus a human breast cancer model and its safety in vivo through well-tolerated animal biological responses, envisaging a possible forthcoming use in clinical trials.

Interfacial reaction between organic acids and iron-containing clay minerals: Hydroxyl radical generation and phenolic compounds degradation

Reactive oxygen species, especially hydroxyl radicals (OH), exert a distinguished role in the transformation of contaminants, and their in-situ generation attracts wide attentions in environmental and geochemical areas. The present work explored the potential formation of OH during the interactions between iron-containing clay minerals and environmentally prevalent organic acids in dark environments. The results demonstrated that the accumulative OH concentrations were related to the solution pH, the types of clay minerals, and the nature of organic acid species. At pH 5.5, 1.2- 15.2 times of OH were generated from the reduction of Na-nontronite-2 (Na-NAu-2) compared with other clay minerals in the presence of ascorbic acid (AA) at 144 h. X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) analyses indicated that Fe(III) was reduced to Fe(II) by AA during OH formation. Meanwhile, chemical probe tests coupled with quenching experiments confirmed the generation of H₂O₂ and superoxide radical (O₂^-), which participated in the formation of OH. The produced OH/O₂^- can transform 68.4%, 86.4%, and 50.1% of phenol, p-nitrophenol, and 2,4-dichlorophenol within 168 h in AA-Na-NAu-2 suspension, respectively. This work provides valuable insights into OH production in the mutual interaction between organic acids and iron-bearing clays, which is helpful for the development of a new method for removing organic pollutants from contaminated water and soil environments.

Ruthenium Complexes: An Alternative to Platinum Drugs in Colorectal Cancer Treatment

Colorectal cancer (CRC) is one of the intimidating causes of death around the world. CRC originated from mutations of tumor suppressor genes, proto-oncogenes and DNA repair genes. Though platinum (Pt)-based anticancer drugs have been widely used in the treatment of cancer, their toxicity and CRC cells' resistance to Pt drugs has piqued interest in the search for alternative metal-based drugs. Ruthenium (Ru)-based compounds displayed promising anticancer activity due to their unique chemical properties. Ru-complexes are reported to exert their anticancer activities in CRC cells by regulating different cell signaling pathways that are either directly or indirectly associated with cell growth, division, proliferation, and migration. Additionally, some Ru-based drug candidates showed higher potency compared to commercially available Pt-based anticancer drugs in CRC cell line models. Meanwhile Ru nanoparticles coupled with photosensitizers or anticancer agents have also shown theranostic potential towards CRC. Ru-nanoformulations improve drug efficacy, targeted drug delivery, immune activation, and biocompatibility, and therefore may be capable of overcoming some of the existing chemotherapeutic limitations. Among the potential Ru-based compounds, only Ru (III)-based drug NKP-1339 has undergone phase-Ib clinical trials in CRC treatment.

Diacetoxy iodobenzene mediated regioselective synthesis and characterization of novel [1,2,4]triazolo[4,3-a]pyrimidines: apoptosis inducer, antiproliferative activities and molecular docking studies

Prompt and regioselective synthesis of eleven novel [1,2,4]triazolo[4,3-a]pyrimidines 2a-2k, via intramolecular oxidative-cyclization of 2-(2-arylidenehydrazinyl)-4-methyl-6-phenylpyrimidine derivatives 1a-1k has been demonstrated here using diacetoxy iodobenzene (DIB) as inexpensive and ecofriendly hypervalent iodine(III) reagent in CH₂Cl₂ at room temperature. Regiochemistry of final product has been established by developing single crystal and studied X-ray crystallographic data for two derivatives 2c and 2h without any ambiguity. These prominent [1,2,4]triazolo[4,3-a]pyrimidines were evaluated for human osteosarcoma bone cancer (MG-63) and breast cancer (MCF-7) cell lines using MTT assay to find potent antiproliferative agent and also on testicular germ cells to find potent apoptotic inducing activities. All compounds show significant cytotoxicity, particularly 3-(2,4-dichlorophenyl)-5-methyl-7-phenyl-[1,2,4]triazolo[4,3-a]pyrimidine (2g) was found significant apoptotic inducing molecule, as well as the most potent cytotoxic agent against bone cancer (MG-63) and breast cancer (MCF-7) cell lines with GI₅₀ value 148.96 µM and 114.3 µM respectively. Molecular docking studies has been carried out to see the molecular interactions of synthesized compounds with the protein thymidylate synthase (PBD ID: 2G8D).Communicated by Ramaswamy H. Sarma.

Designing Ruthenium Anticancer Drugs: What Have We Learnt from the Key Drug Candidates?

After nearly 20 years of research on the use of ruthenium in the fight against cancer, only two Ru(III) coordination complexes have advanced to clinical trials. During this time, the field has produced excellent candidate drugs with outstanding in vivo and in vitro activity; however, we have yet to find a ruthenium complex that would be a viable alternative to platinum drugs currently used in the clinic. We aimed to explore what we have learned from the most prominent complexes in the area, and to challenge new concepts in chemical design. Particularly relevant are studies involving NKP1339, NAMI-A, RM175, and RAPTA-C, which have paved the way for current research. We explored the development of the ruthenium anticancer field considering that the mechanism of action of complexes no longer focuses solely on DNA interactions, but explores a diverse range of cellular targets involving multiple chemical strategies.