title: New pyrazolobenzothiazine derivatives as hepatitis C virus NS5B polymerase palm site I inhibitors.
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.
authors.affiliation: Dipartimento di Scienze Farmaceutiche, Università degli Studi di Perugia , Via A. Fabretti 48, 06123 Perugia, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Manfroni
authors.forename: Dinesh
authors.initials: D
authors.lastname: Manvar
authors.forename: Maria Letizia
authors.initials: ML
authors.lastname: Barreca
authors.forename: Neerja
authors.initials: N
authors.lastname: Kaushik-Basu
authors.forename: Pieter
authors.initials: P
authors.lastname: Leyssen
authors.forename: Jan
authors.initials: J
authors.lastname: Paeshuyse
authors.forename: Rolando
authors.initials: R
authors.lastname: Cannalire
authors.forename: Nunzio
authors.initials: N
authors.lastname: Iraci
authors.forename: Amartya
authors.initials: A
authors.lastname: Basu
authors.forename: Maxim
authors.initials: M
authors.lastname: Chudaev
authors.forename: Claudio
authors.initials: C
authors.lastname: Zamperini
authors.forename: Elena
authors.initials: E
authors.lastname: Dreassi
authors.forename: Stefano
authors.initials: S
authors.lastname: Sabatini
authors.forename: Oriana
authors.initials: O
authors.lastname: Tabarrini
authors.forename: Johan
authors.initials: J
authors.lastname: Neyts
authors.forename: Violetta
authors.initials: V
authors.lastname: Cecchetti
mesh_terms: D000998:Antiviral Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D001665:Binding Sites; D015195:Drug Design; D016174:Hepacivirus / Q000187:drug effects; D006801:Humans; D011720:Pyrazoles / Q000138:chemical synthesis* / Q000494:pharmacology; D013329:Structure-Activity Relationship; D017361:Viral Nonstructural Proteins / Q000037:antagonists & inhibitors*; D012324:RNA-Dependent RNA Polymerase
chemical_list: D000998:Antiviral Agents; D011720:Pyrazoles; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase