Complexes [Au(III)X(2)(dtc-Sar-AA-O(t-Bu))] (AA = Gly, X = Br (1)/Cl (2); AA = Aib, X = Br (3)/Cl (4); AA = l-Phe, X = Br (5)/Cl (6)) were designed on purpose in order to obtain gold(III)-based anticancer peptidomimetics that might specifically target two peptide transporters (namely, PEPT1 and PEPT2) upregulated in several tumor cells. All the compounds were characterized by means of FT-IR and mono- and multidimensional NMR spectroscopy, and the crystal structure of [Au(III)Br(2)(dtc-Sar-Aib-O(t-Bu))] (3) was solved and refined. According to in vitro cytotoxicity studies, the Aib-containing complexes 3 and 4 turned out to be the most effective toward all the human tumor cell lines evaluated (PC3, DU145, 2008, C13, and L540), reporting IC(50) values much lower than that of cisplatin. Remarkably, they showed no cross-resistance with cisplatin itself and were proved to inhibit tumor cell proliferation by inducing either apoptosis or late apoptosis/necrosis depending on the cell lines. Biological results are here reported and discussed in terms of the structure-activity relationship.
Indomethacin (INM), a well-known non-steroidal anti-inflammatory drug, has recently gained attention for its antiviral activity demonstrated in drug repurposing studies against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Although the mechanism of action of INM is not yet fully understood, recent studies have indicated that it acts at an early stage of the coronaviruses (CoVs) replication cycle. In addition, a proteomic study reported that the anti-SARS-CoV-2 activity of INM could be also ascribed to its ability to inhibit human prostaglandin E synthase type 2 (PGES-2), a host protein which interacts with the SARS-CoV-2 NSP7 protein. Although INM does not potently inhibit SARS-CoV-2 replication in infected Vero E6 cells, here we have explored for the first time the application of the Proteolysis Targeting Chimeras (PROTACs) technology in order to develop more potent INM-derived PROTACs with anti-CoV activity. In this study, we report the design, synthesis, and biological evaluation of a series of INM-based PROTACs endowed with antiviral activity against a panel of human CoVs, including different SARS-CoV-2 strains. Two PROTACs showed a strong improvement in antiviral potency compared to INM. Molecular modelling studies support human PGES-2 as a potential target of INM-based antiviral PROTACs, thus paving the way toward the development of host-directed anti-CoVs strategies. To the best of our knowledge, these PROTACs represent the first-in-class INM-based PROTACs with antiviral activity and also the first example of the application of PROTACs to develop pan-coronavirus agents.
We synthesized, characterized and tested in a panel of cancer cell lines, nine new bipyridine gold(III) dithiocarbamate-containing complexes. In vitro studies demonstrated that compounds 1, 2, 4, 5, 7 and 8 were the most cytotoxic in prostate, breast, ovarian cancer cell lines and in Hodgkin lymphoma cells with IC50 values lower than the reference drug cisplatin. The most active compound 1 was more active than cisplatin in ovarian (A2780cis and 2780CP-16) and breast cancer cisplatin-resistant cells. Compound 1 determined an alteration of the cellular redox homeostasis leading to increased ROS levels, a decrease in the mitochondrial membrane potential, cytochrome-c release from the mitochondria and activation of caspases 9 and 3. The ROS scavenger NAC suppressed ROS generation and rescued cells from damage. Compound 1 resulted more active in tumor cells than in normal human Mesenchymal stromal cells. Gold compounds were active independent of p53 status: exerted cytotoxic effects on a panel of non-small cell lung cancer cell lines with different p53 status and in the ovarian A2780 model where the p53 was knocked out. In conclusion, these promising results strongly indicate the need for further preclinical evaluation to test the clinical potential of these new gold(III) complexes.
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