Author:

Keywords:

Science & Technology, Life Sciences & Biomedicine, Microbiology, Pharmacology & Pharmacy, NS4B protein, SAR studies, Zika virus, cross resistance, dengue virus, indole alkaloids, mechanisms of action, NS4B PROTEIN, SEQUENCE, PATHOGENESIS, ALIGNMENT, AGENTS, Dengue, Humans, Indole Alkaloids, Viral Nonstructural Proteins, Virus Replication, Zika Virus, Zika Virus Infection, 0605 Microbiology, 1108 Medical Microbiology, 1115 Pharmacology and Pharmaceutical Sciences, 3107 Microbiology, 3207 Medical microbiology, 3214 Pharmacology and pharmaceutical sciences

Abstract:

Here, we identified a novel class of compounds which demonstrated good antiviral activity against dengue and Zika virus infection. These derivatives constitute intermediates in the synthesis of indole (ervatamine-silicine) alkaloids and share a tetracyclic structure, with an indole and a piperidine fused to a seven-membered carbocyclic ring. Structure-activity relationship studies indicated the importance of substituent at position C-6 and especially the presence of a benzyl ester for the activity and cytotoxicity of the molecules. In addition, the stereochemistry at C-7 and C-8, as well as the presence of an oxazolidine ring, influenced the potency of the compounds. Mechanism of action studies with two analogues of this family (compounds 22 and trans-14) showed that this class of molecules can suppress viral infection during the later stages of the replication cycle (RNA replication/assembly). Moreover, a cell-dependent antiviral profile of the compounds against several Zika strains was observed, possibly implying the involvement of a cellular factor(s) in the activity of the molecules. Sequencing of compound-resistant Zika mutants revealed a single nonsynonymous amino acid mutation (aspartic acid to histidine) at the beginning of the predicted transmembrane domain 1 of NS4B protein, which plays a vital role in the formation of the viral replication complex. To conclude, our study provides detailed information on a new class of NS4B-associated inhibitors and strengthens the importance of identifying host-virus interactions in order to tackle flavivirus infections.