Exploring chromone sulfonamides and sulfonylhydrazones as highly selective ectonucleotidase inhibitors: Synthesis, biological evaluation and in silico study.

Ectonucleotidases, a well-known superfamily of plasma membrane located metalloenzymes plays a central role in mediating the process of purinergic cell signaling. Major functions performed by these enzymes include the hydrolysis of extracellular nucleosides and nucleotides which are considered as important cell-signaling molecules. Any (patho)-physiologically induced disruption in this purinergic cell signaling leads to several disorders, hence these enzymes are important drug targets for therapeutic purposes. Among the major challenges faced in the design of inhibitors of ectonucleotidases, an important one is the lack of selective inhibitors. Access to highly selective inhibitors via a facile synthetic route will not only be beneficial therapeutically, but will also lead to an increase in our understanding of intricate interplay between members of ectonucleotidase enzymes in relation to their selective activation and/or inhibition in different cells and tissues. Herein we describe synthesis of highly selective inhibitors of human intestinal alkaline phosphatase (h-IAP) and human tissue non-specific alkaline phosphatase (h-TNAP), containing chromone sulfonamide and sulfonylhydrazone scaffolds. Compound 1c exhibited highest (and most selective) h-IAP inhibition activity (h-IAP IC50 = 0.51 ± 0.20 µM; h-TNAP = 36.5%) and compound 3k showed highest activity and selective inhibition against h-TNAP (h-TNAP IC50 = 1.41 ± 0.10 µM; h-IAP = 43.1%). These compounds were also evaluated against another member of ectonucleotidase family, that is rat and human ecto-5'-nucleotidase (r-e5'NT and h-e5'NT). Some of the compounds exhibited excellent inhibitory activity against ecto-5'-nucleotidase. Compound 2 g exhibited highest inhibition against h-e5'NT (IC50 = 0.18 ± 0.02 µM). To rationalize the interactions with the binding site, molecular docking studies were carried out.

Design, Synthesis, and Biological Evaluation of Novel Dihydropyridine and Pyridine Analogs as Potent Human Tissue Nonspecific Alkaline Phosphatase Inhibitors with Anticancer Activity: ROS and DNA Damage-Induced Apoptosis.

Small molecules with nitrogen-containing scaffolds have gained much attention due to their biological importance in the development of new anticancer agents. The present paper reports the synthesis of a library of new dihydropyridine and pyridine analogs with diverse pharmacophores. All compounds were tested against the human tissue nonspecific alkaline phosphatase (h-TNAP) enzyme. Most of the compounds showed excellent enzyme inhibition against h-TNAP, having IC50 values ranging from 0.49 ± 0.025 to 8.8 ± 0.53 µM, which is multi-fold higher than that of the standard inhibitor (levamisole = 22.65 ± 1.60 µM) of the h-TNAP enzyme. Furthermore, an MTT assay was carried out to evaluate cytotoxicity against the HeLa and MCF-7 cancer cell lines. Among the analogs, the most potent dihydropyridine-based compound 4d was selected to investigate pro-apoptotic behavior. The further analysis demonstrated that compound 4d played a significant role in inducing apoptosis through multiple mechanisms, including overproduction of reactive oxygen species, mitochondrial dysfunction, DNA damaging, and arrest of the cell cycle at the G1 phase by inhibiting CDK4/6. The apoptosis-inducing effect of compound 4d was studied through staining agents, microscopic, and flow cytometry techniques. Detailed structure-activity relationship (SAR) and molecular docking studies were carried out to identify the core structural features responsible for inhibiting the enzymatic activity of the h-TNAP enzyme. Moreover, fluorescence emission studies corroborated the binding interaction of compound 4d with DNA through a fluorescence titration experiment.