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Structure-activity relationships of HCV NS3 protease inhibitors evaluated on the drug-resistant variants A156T and D168V
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Biochemistry. (U Helena Danielson)
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Biochemistry.
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2010 (English)In: Antiviral Therapy, ISSN 1359-6535, Vol. 15, no 6, 841-852 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: HCV infections are a serious threat to public health. An important drug target is the NS3 protease, for which several inhibitors are in clinical trials. Because of the high mutation rate of the virus, resistance against any HCV-specific drug is likely to become a substantial problem. Structure-activity data for the major resistant variants are therefore needed to guide future designs of protease inhibitors. METHODS: The inhibitory potency of tripeptide NS3 protease inhibitors, with either a P2 proline or phenylglycine, in combination with different P3 and P1-P1' groups, was assessed in enzyme activity assays using the full-length NS3 protein with known resistance-conferring substitutions A156T or D168V. The results obtained from these variants were compared with the inhibition of the wild-type enzyme. Molecular modelling was used to rationalize the biochemical results. RESULTS: Inhibitors combining the P2 proline and P1 (1R,2S)-1-amino-2-vinylcyclopropyl-carboxylic acid (vinylACCA) lost much of their potency on the resistant variants. Exchange of the P2 proline for phenylglycine yielded inhibitors that were equipotent on the wild-type and on the A156T and D168V variants. The same result was obtained from the combination of either the P2 residue with a norvaline or an aromatic scaffold in the P1 position. CONCLUSIONS: The combination of a substituted P2 proline and P1 vinylACCA appears to be the main problem behind the observed resistance. Molecular modelling suggests an enforced change in binding conformation for the P2 proline-based inhibitors, whereas the phenylglycine-based inhibitors retained their wild-type binding conformation in the substituted forms of the enzyme.

Place, publisher, year, edition, pages
2010. Vol. 15, no 6, 841-852 p.
National Category
Pharmaceutical Sciences Chemical Sciences
URN: urn:nbn:se:uu:diva-131962DOI: 10.3851/IMP1655ISI: 000282390300004PubMedID: 20834096OAI: oai:DiVA.org:uu-131962DiVA: diva2:356269
Available from: 2010-10-12 Created: 2010-10-12 Last updated: 2014-10-01Bibliographically approved
In thesis
1. Novel Procedures for Identification and Characterization of Viral Proteases Inhibitors
Open this publication in new window or tab >>Novel Procedures for Identification and Characterization of Viral Proteases Inhibitors
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Viral proteases are often considered to be attractive drug targets because of their crucial function in the viral replication machinery. In order to increase our knowledge of these important targets and to contribute to the discovery and development of new antiviral drugs, the proteases from hepatitis C virus (HCV) and human cytomegalovirus (HCMV) have been produced and their interactions with inhibitors and fragments have been characterized, using enzyme inhibition and SPR biosensor based interaction assay.

The structure activity relationships and the resistance profiles of a series of HCV NS3 protease inhibitors based on either P2 proline or phenylglycine residues were analyzed using wild type genotype 1a and the major resistant variants A156T and D168V. The observed susceptibility to substitutions associated with these resistance variants was concluded to depend on the P2 and the P1 residue, and not only on the P2 residue as previously had been suggested. In order to be able to evaluate how the potency of inhibitors is affected by genetic variation, their effect was evaluated on wild type NS3 from genotype 1a, 1b and 3a as well as on the resistant variant R155K from genotype 1a. To enable a comparison of the inhibitory effect on the enzyme variants, the compounds were analyzed under conditions optimized for each variant. VX-950 was found to be the least susceptible compound to resistance and genetic variation. A more detailed analysis showed that the kinetic and mechanistic features of the inhibitors were significantly different for the different genotypes. The reversible non covalent macrocyclic inhibitor ITMN 191 was revealed to have favorable kinetics for all three genotypes. This is an advantage for the design of broad spectrum drugs.

A fragment based procedure for identifying and validating novel scaffolds for inhibitors of HCMV protease was established. It identified fragments that may serve as starting points for the discovery of effective inhibitors against this challenging target.  

The procedures developed for the evaluation and identification of novel HCV NS3 and HCMV protease inhibitors have contributed to a deeper understanding of protease-inhibitor interactions that is expected to have an impact on the design of novel antiviral drugs. 

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. 50 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1115
drug discovery, viral proteases, inhibitors, Hepatitis C, NS3, cytomegalovirus
National Category
Chemical Sciences
Research subject
urn:nbn:se:uu:diva-215700 (URN)978-91-554-8855-0 (ISBN)
Public defence
2014-02-28, B42, BMC, Uppsala Universitet, Husargatan 3, 751 23, Uppsala, 13:15 (English)
Available from: 2014-02-07 Created: 2014-01-15 Last updated: 2014-02-10

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