n-nonyl-1-deoxynojirimycin and Dengue

The dengue virus and related flaviviruses are an increasing global health threat. In this perspective, we comment on and review medicinal chemistry efforts aimed at the prevention or treatment of dengue infections. We include target-based approaches aimed at viral or host factors and results from phenotypic screenings in cellular assay systems for viral replication. This perspective is limited to the discussion of results that provide explicit chemistry or structure-activity relationship (SAR), or appear to be of particular interest to the medicinal chemist for other reasons. The discovery and development efforts discussed here may at least partially be extrapolated toward other emerging flaviviral infections, such as West Nile virus. Therefore, this perspective, although not aimed at flaviviruses in general, should also be able to provide an overview of the medicinal chemistry of these closely related infectious agents.

Topics: Antiviral Agents; Chemistry, Pharmaceutical; Dengue; Dengue Virus; Humans; Molecular Conformation; Structure-Activity Relationship

We recently described the discovery of oxygenated N-alkyl deoxynojirimycin (DNJ) derivative 7 (CM-10-18) with antiviral activity against dengue virus (DENV) infection both in vitro and in vivo. This imino sugar was promising but had an EC(50) against DENV in BHK cells of 6.5 μM, which limited its use in in vivo. Compound 7 presented structural opportunities for activity relationship analysis, which we exploited and report here. These structure-activity relationship studies led to analogues 2h, 2l, 3j, 3l, 3v, and 4b-4c with nanomolar antiviral activity (EC(50) = 0.3-0.5 μM) against DENV infection, while maintaining low cytotoxicity (CC(50) > 500 μM, SI > 1000). In male Sprague-Dawley rats, compound 3l was well tolerated at a dose up to 200 mg/kg and displayed desirable PK profiles, with significantly improved bioavailability (F = 92 ± 4%).

Topics: 1-Deoxynojirimycin; alpha-Glucosidases; Animals; Antiviral Agents; Biological Availability; Cattle; Cell Line; Cricetinae; Dengue; Dengue Virus; Diarrhea Viruses, Bovine Viral; Glycoside Hydrolase Inhibitors; Humans; Male; Microbial Sensitivity Tests; Rats; Rats, Sprague-Dawley; Structure-Activity Relationship; Viral Envelope Proteins; Virus Replication

Dengue fever is an emerging arboviral disease for which no vaccine or antiviral treatment exists and that causes thousands of fatalities each year. To develop an in vivo test system for antidengue drugs, AG129 mice, which are deficient for the interferon- alpha / beta and - gamma receptors, were injected with unadapted dengue virus, resulting in a dose-dependent transient viremia lasting several days and peaking on day 3 after infection. Additionally, nonstructural protein 1, increased levels of proinflammatory cytokines, and neutralizing IgM and IgG antibodies were found, and mice had splenomegaly. Oral administration of the antiviral compounds 7-deaza-2'-C-methyl-adenosine, N-nonyl-deoxynojirimycin, or 6-O-butanoyl castanospermine significantly reduced viremia in a dose-dependent manner, even after delayed treatment, leading to a reduction of splenomegaly and proinflammatory cytokine levels. The results validate this dengue viremia mouse model as a suitable system for testing antidengue drugs and indicate that antiviral treatment during the acute phase of dengue fever can reduce the severity of the disease.

Topics: 1-Deoxynojirimycin; Animals; Antiviral Agents; Dengue; Disease Models, Animal; Dose-Response Relationship, Drug; Indolizines; Mice; Ribavirin; Time Factors; Tubercidin; Viremia; Virus Replication

Endoplasmic reticulum (ER) alpha-glucosidase inhibitors, which block the trimming step of N-linked glycosylation, have been shown to eliminate the production of several ER-budding viruses. Here we investigated the effects of one such inhibitor, N-nonyl-deoxynojirimycin (NN-DNJ), a 9-carbon alkyl iminosugar derivative, on infection by Japanese encephalitis virus (JEV) and dengue virus serotype 2 (DEN-2). In the presence of NN-DNJ, JEV and DEN-2 infections were suppressed in a dose-dependent manner. This inhibitory effect appeared to influence DEN-2 infection more than JEV infection, since lower concentrations of NN-DNJ substantially blocked DEN-2 replication. Secretion of the flaviviral glycoproteins E and NS1 was greatly reduced, and levels of DEN-2 viral RNA replication measured by fluorogenic reverse transcription-PCR were also decreased, by NN-DNJ. Notably, the viral glycoproteins, prM, E, and NS1 were found to associate transiently with the ER chaperone calnexin, and this interaction was affected by NN-DNJ, suggesting a potential role of calnexin in the folding of flaviviral glycoproteins. Additionally, in a mouse model of lethal challenge by JEV infection, oral delivery of NN-DNJ reduced the mortality rate. These findings show that NN-DNJ has an antiviral effect on flavivirus infection, likely through interference with virus replication at the posttranslational modification level, occurring mainly in the ER.

Topics: 1-Deoxynojirimycin; Animals; Antiviral Agents; Cell Line; Cricetinae; Dengue; Dengue Virus; Encephalitis Virus, Japanese; Encephalitis, Japanese; Female; Glycoside Hydrolase Inhibitors; Mice; Mice, Inbred ICR