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High-throughput Antiviral Assays to Screen for Inhibitors of Zika Virus Replication
Published on: October 30, 2021
New pyrazolobenzothiazine derivatives as hepatitis C virus NS5B polymerase palm site I inhibitors
Giuseppe Manfroni1, Dinesh Manvar, Maria Letizia Barreca
1Dipartimento di Scienze Farmaceutiche, Università degli Studi di Perugia , Via A. Fabretti 48, 06123 Perugia, Italy.
Abstract:
We have previously identified the pyrazolobenzothiazine scaffold as a promising chemotype against hepatitis C virus (HCV) NS5B polymerase, a validated and promising anti-HCV target. Herein we describe the design, synthesis, enzymatic, and cellular characterization of new pyrazolobenzothiazines as anti-HCV inhibitors. The binding site for a representative derivative was mapped to NS5B palm site I employing a mutant counterscreen assay, thus validating our previous in silico predictions. Derivative 2b proved to be the best selective anti-HCV derivative within the new series, exhibiting a IC50 of 7.9 μM against NS5B polymerase and antiviral effect (EC50 = 8.1 μM; EC90 = 23.3 μM) coupled with the absence of any antimetabolic effect (CC50 > 224 μM; SI > 28) in a cell based HCV replicon system assay. Significantly, microscopic analysis showed that, unlike the parent compounds, derivative 2b did not show any significant cell morphological alterations. Furthermore, since most of the pyrazolobenzothiazines tested altered cell morphology, this undesired aspect was further investigated by exploring possible perturbation of lipid metabolism during compound treatment.
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