Piperazine amides with desirable solubility, physicochemical and drug-like properties: Synthesis and evaluation of the anti-Trypanosoma cruzi activity

Design, Synthesis, and Structure-Activity Relationship of 2-(Piperazin-1-yl)quinazolin-4(3H)-one Derivatives as Active Agents against Toxoplasma gondii

A novel series of quinazolin-4(3H)-one derivatives were synthesized using a hybridization strategy that combined the quinazolin-4(3H)-one scaffold, the diarylether fragment, and the piperazine ring. The in vitro activity evaluation of these compounds against Toxoplasma gondii demonstrated that most of this series of compounds showed moderate to good effectiveness, with IC50 values ranging from 5.94 to 102.2 μM. Among the synthesized derivatives, compounds 11 and 18 emerged as the most potent inhibitors, significantly reducing the replication rate of T. gondii with IC50 values of 6.33 and 5.94 μM, as well as demonstrated low cytotoxicity with CC50 values of 285 and 59.2 μM, respectively. The structure-activity relationship investigation indicates that the substituent at the N-3 position of the quinazolin-4(3H)-one is important for anti-T. gondii activity while the replacements at the phenyl moiety of the quinazolin-4(3H)-one and at the diarylether fragment cannot improve activity. The invasion and proliferation assay demonstrated that compound 11 could inhibit both parasite invasion and replication ability. Further investigation of the in vitro efficacy revealed irreversible action of compound 11 against T. gondii. In vivo investigations conducted within a murine model of acute infection revealed that compounds 11 and 18 exhibited a remarkable capacity to significantly diminish the parasitic load in comparison to the control group while also extending the survival duration of the subjects. These results underscore the potential of compound 11 as a candidate for further exploration in the development of antitoxoplasmosis therapies.

Nanomolar activity of coumarin-3-thiosemicarbazones targeting Trypanosoma cruzi cruzain and the T. brucei cathepsin L-like protease

Trypanosoma cruzi (T. cruzi) and Trypanosoma brucei (T. brucei) urgently demand innovative drug development due to their impact on public health worldwide. Their cysteine proteases, Cruzain (CRZ) and the T. brucei Cathepsin L-like protease (TbrCATL) are established drug targets for these parasites. In this study, our coumarin-3-thiosemicarbazones demonstrated nanomolar IC50 values (22-698 nM) toward these proteases. Against T. cruzi amastigotes and T. brucei trypomastigotes, LASF-01 displayed a promising result. Herein, MCG-02, the most potent TbrCATL inhibitor, underwent comprehensive analyses, including cytotoxicity assessments and in vitro tests. Molecular dynamics (MD) simulations and a multiscale Quantum Mechanics/Quantum Mechanics (QM/QM) approach were used to generate insights into their binding modes. These suggested that MCG-02 could be a reversible, competitive covalent inhibitor. Further, confirmatory assays were experimentally performed changing different parameters to prove its efficacy. Additionally, the predicted pharmacokinetic profile showed that there is no violation of the Lipinski rule of five. Notably, coumarin-3-thiosemicarbazone hybrids emerged as promising candidates for designing highly active inhibitors against CRZ and TbrCATL. Overall, the integration of in silico and experimental approaches enhanced our understanding regarding the binding modes of MCG-02, which were experimentally corroborated, providing valuable insights for future drug development.

Development of a Two-Photon-Responsive Chromophore, 2-(p-Aminophenyl)-5,6-dimethoxy-1-(hydroxyinden-3-yl)methyl Derivative, as a Photoremovable Protecting Group

Photoremovable protecting groups (PPGs) are powerful tools that are widely used to investigate biological events in cells. An important requirement for PPGs is the efficient release of bioactive molecules by using visible to near-infrared light in the biological window (650-1350 nm). In this study, we report a new two-photon (2P)-responsive PPG, 2-(p-aminophenyl)-5,6-dimethoxy-1-(hydroxyinden-3-yl)methyl, with a donor-π-donor cyclic stilbene structure. The 2P cross section was approximately 40-50 GM at ∼700 nm. The quantum yield of the uncaging process of caged benzoate was greater than 0.7, demonstrating that the 2P uncaging efficiency was approximately 30 GM at around 700 nm. This newly developed 2P-responsive chromophore can be used in future biological experiments. The mechanism of the photo-uncaging reaction via the carbocation intermediate was elucidated using transient absorption spectroscopy and product analysis.