Optimization of a fragment linking hit toward Dengue and Zika virus NS5 methyltransferases inhibitors

No antiviral drugs to treat or prevent life-threatening flavivirus infections such as those caused by mosquito-borne Dengue (DENV) and more recently Zika (ZIKV) viruses are yet available. We aim to develop, through a structure-based drug design approach, novel inhibitors targeting the NS5 AdoMet-dependent mRNA methyltransferase (MTase), a viral protein involved in the RNA capping process essential for flaviviruses replication. Herein, we describe the optimization of a hit (5) identified using fragment-based and structure-guided linking techniques, which binds to a proximal site of the AdoMet binding pocket. X-ray crystallographic structures and computational docking were used to guide our optimization process and lead to compounds 30 and 33 (DENV IC50 = 26 mu M and 23 mu M; ZIKV IC50 = 28 mu M and 19 mu M, respectively), two representatives of novel non-nucleoside inhibitors of flavivirus MTases. (C) 2018 Elsevier Masson SAS. All rights reserved.