Substituted sulfonamide bioisosteres of 8-hydroxyquinoline as zinc-dependent antibacterial compounds

Searching for "Greener" Bioequivalents of CF3 to Lower its Environmental Impact

Considering the broad use of the trifluoromethyl functional group (-CF3) in medicinal chemistry and taking into account the recent concerns on the negative environmental effects of CF3 containing compounds, we are searching for "greener" alternatives. Thus, different chemical groups (i. e. iodide, fluoride, cyclopropyl, isopropyl, cyclobutyl, 3-oxetyl, 2-oxetyl, methylsulfide, pentafluorosulfide, methylsulfonyl and sulfonamide) have been considered as potential bioequivalents of -CF3 aiming to use them in compounds with therapeutic interest instead of the polyfluoride functionality. Different structural (molecular surface and volume) and physicochemical (electronic and lipophilic) aspects of the bioequivalent functionalities proposed have been theoretically calculated and compared to those of -CF3. Additionally, the corresponding phenyl derivatives carrying these functionalities have been purchased or prepared and their experimental lipophilicity (i. e. LogP) measured using shake-flask experiments and UV-vis spectroscopy.

Developing Metal-Binding Isosteres of 8-Hydroxyquinoline as Metalloenzyme Inhibitor Scaffolds

The use of metal-binding pharmacophores (MBPs) in fragment-based drug discovery has proven effective for targeted metalloenzyme drug development. However, MBPs can still suffer from pharmacokinetic liabilities. Bioisostere replacement is an effective strategy utilized by medicinal chemists to navigate these issues during the drug development process. The quinoline pharmacophore and its bioisosteres, such as quinazoline, are important building blocks in the design of new therapeutics. More relevant to metalloenzyme inhibition, 8-hydroxyquinoline (8-HQ) and its derivatives can serve as MBPs for metalloenzyme inhibition. In this report, 8-HQ isosteres are designed and the coordination chemistry of the resulting metal-binding isosteres (MBIs) is explored using a bioinorganic model complex. In addition, the physicochemical properties and metalloenzyme inhibition activity of these MBIs were investigated to establish drug-like profiles. This report provides a new group of 8-HQ-derived MBIs that can serve as novel scaffolds for metalloenzyme inhibitor development with tunable, and potentially improved, physicochemical properties.

Zinc ionophores: chemistry and biological applications

Zinc can play a pathophysiological role in several diseases and can interfere in key processes of microbial growth. This evidence justifies the efforts in applying Zinc ionophores to restore Zinc homeostasis and treat bacterial/viral infections such as coronavirus diseases. Zinc ionophores increase the intracellular concentration of Zinc ions causing significant biological effects. This review provides, for the first time, an overview of the applications of the main Zinc ionophores in Zinc deficiency, infectious diseases, and in cancer, discussing the pharmacological and coordination properties of the Zinc ionophores.

Novel Antimicrobial 8-Hydroxyquinoline-Based Agents: Current Development, Structure-Activity Relationships, and Perspectives

The search for new antimicrobials is imperative due to the emergent resistance of new microorganism strains. In this context, revisiting known classes like 8-hydroxyquinolines could be an interesting strategy to discover new agents. The 8-hydroxyquinoline derivatives nitroxoline and clioquinol are used to treat microbial infections; however, these drugs are underused, being available in few countries or limited to topical use. After years of few advances, in the last two decades, the potent activity of clioquinol and nitroxoline against several targets and the privileged structure of 8-hydroxyquinoline nucleus have prompted an increased interest in the design of novel antimicrobial, anticancer, and anti-Alzheimer agents based on this class. Herein, we discuss the current development and antimicrobial structure-activity relationships of this class in the perspective of using the 8-hydroxyquinoline nucleus for the search for novel antimicrobial agents. Furthermore, the most investigated molecular targets concerning 8-hydroxyquinoline derivatives are explored in the final section.

The effectiveness of a nonalcoholic disinfectant containing metal ions, with broad antimicrobial activity

Disinfectants have different efficacies depending on their use and the target microorganism. This study aimed to evaluate the efficacy and safety of our new nonalcoholic disinfectant, which consists mainly of metal ions. According to the 17th revised Japanese Pharmacopoeia and ASTM international E1052 method, the bactericidal and virucidal efficacy of this new disinfectant against 13 microorganisms was evaluated by the in vitro quantitative suspension test. Additionally, the disinfectant cytotoxicity against multiple cell lines was examined. Then, a safety test using a human open patch test was performed with 26 healthy volunteers. This disinfectant showed strong bactericidal and virucidal activities: all microorganisms except enterovirus were inactivated very quickly. The infectivity of 12 microbial strains was eliminated within 5 min of disinfectant exposure. Additionally, this disinfectant showed little acute cytotoxicity in vitro. All volunteers were negative in the human open patch test. Our new disinfectant has a broad spectrum of microbial targets, is safe for human skin, and demonstrates no cytotoxicity. This disinfectant could prevent common microbial infections.

C-2 derivatized 8-sulfonamidoquinolines as antibacterial compounds

A series of C-2 derivatized 8-sulfonamidoquinolines were evaluated for their antibacterial activity against the common mastitis causative pathogens Streptococcus uberis, Staphylococcus aureus and Escherichia coli, both in the presence and absence of supplementary zinc (50 µM ZnSO₄). The vast majority of compounds tested were demonstrated to be significantly more active against S. uberis when in the presence of supplementary zinc (MICs as low as 0.125 µg/mL were observed in the presence of 50 µM ZnSO₄). Compounds 5, 34-36, 39, 58, 79, 82, 94 and 95 were shown to display the greatest antibacterial activity against S. aureus (MIC ≤ 8 µg/mL; both in the presence and absence of supplementary zinc), while compounds 56, 58 and 66 were demonstrated to also exhibit activity against E. coli (MIC ≤ 16 µg/mL; under all conditions). Compounds 56, 58 and 66 were subsequently confirmed to be bactericidal against all three mastitis pathogens studied, with MBCs (≥3log₁₀ CFU/mL reduction) of ≤ 32 µg/mL (in both the presence and absence of 50 µM ZnSO₄). To validate the sanitizing activity of compounds 56, 58 and 66, a quantitative suspension disinfection (sanitizer) test was performed. Sanitizing activity (>5log₁₀ CFU/mL reduction in 5 min) was observed against both S. uberis and E. coli at compound concentrations as low as 1 mg/mL (compounds 56, 58 and 66), and against S. aureus at 1 mg/mL (compound 58); thereby validating the potential of compounds 56, 58 and 66 to function as topical sanitizers designed explicitly for use in non-human applications.

Zinc(II)-The Overlooked Éminence Grise of Chloroquine's Fight against COVID-19?

Zn(II) is an inhibitor of SARS-CoV-2's RNA-dependent RNA polymerase, and chloroquine and hydroxychloroquine are Zn(II) ionophores-this statement gives a curious mind a lot to think about. We show results of the first clinical trials on chloroquine (CQ) and hydroxychloroquine (HCQ) in the treatment of COVID-19, as well as earlier reports on the anticoronaviral properties of these two compounds and of Zn(II) itself. Other FDA-approved Zn(II) ionophores are given a decent amount of attention and are thought of as possible COVID-19 therapeutics.