Discovery of Imidazole-Based Inhibitors of Plasmodium falciparum cGMP-Dependent Protein Kinase

Development of di-arylated 1,2,4-triazole-based derivatives as therapeutic agents against breast cancer: synthesis and biological evaluation

The synthesis, anticancer activity, and metabolic stability of di-arylated 1,2,4-triazole molecules have been reported. Utilizing an efficient programmed arylation technique which starts from commercially available 3-bromo-1H-1,2,4-triazole, a series of therapeutic agents have been synthesized and screened against three human breast cancer cell lines, MDA-MB-231, MCF-7, and ZR-75-1, via an in vitro growth inhibition assay. At 10 μM concentration, 4k, 4m, 4q, and 4t have displayed good anticancer potency in the MCF-7 cell line, among which 4q has shown the best efficacy (IC50 = 4.8 μM). Mechanistic investigations of 4q have indicated the elevation of the pro-apoptotic BAX protein in the malignant cells along with mitochondrial outer membrane permeabilization which are hallmarks of apoptosis. Further metabolic stability studies in diverse liver microsomes have provided insights into the favorable pharmacokinetic properties of 4q in humans, establishing it as a promising lead compound of this series that deserves further investigation.

Structure-Activity Relationship of a Pyrrole Based Series of PfPKG Inhibitors as Anti-Malarials

Controlling malaria requires new drugs against Plasmodium falciparum. The P. falciparum cGMP-dependent protein kinase (PfPKG) is a validated target whose inhibitors could block multiple steps of the parasite's life cycle. We defined the structure-activity relationship (SAR) of a pyrrole series for PfPKG inhibition. Key pharmacophores were modified to enable full exploration of chemical diversity and to gain knowledge about an ideal core scaffold. In vitro potency against recombinant PfPKG and human PKG were used to determine compound selectivity for the parasite enzyme. P. berghei sporozoites and P. falciparum asexual blood stages were used to assay multistage antiparasitic activity. Cellular specificity of compounds was evaluated using transgenic parasites expressing PfPKG carrying a substituted "gatekeeper" residue. The structure of PfPKG bound to an inhibitor was solved, and modeling using this structure together with computational tools was utilized to understand SAR and establish a rational strategy for subsequent lead optimization.

Parasite and host kinases as targets for antimalarials

INTRODUCTION

The deployment of Artemisinin-based combination therapies and transmission control measures led to a decrease in the global malaria burden over the recent decades. Unfortunately, this trend is now reversing, in part due to resistance against available treatments, calling for the development of new drugs against untapped targets to prevent cross-resistance.

AREAS COVERED

In view of their demonstrated druggability in noninfectious diseases, protein kinases represent attractive targets. Kinase-focussed antimalarial drug discovery is facilitated by the availability of kinase-targeting scaffolds and large libraries of inhibitors, as well as high-throughput phenotypic and biochemical assays. We present an overview of validated Plasmodium kinase targets and their inhibitors, and briefly discuss the potential of host cell kinases as targets for host-directed therapy.

EXPERT OPINION

We propose priority research areas, including (i) diversification of Plasmodium kinase targets (at present most efforts focus on a very small number of targets); (ii) polypharmacology as an avenue to limit resistance (kinase inhibitors are highly suitable in this respect); and (iii) preemptive limitation of resistance through host-directed therapy (targeting host cell kinases that are required for parasite survival) and transmission-blocking through targeting sexual stage-specific kinases as a strategy to protect curative drugs from the spread of resistance.