Berberine Inhibits Dengue Virus through Dual Mechanisms

Abstract

Mosquito transmitted viruses, particularly those of the genus Flavivirus, are a significant healthcare burden worldwide, especially in tropical and sub-tropical areas. However, effective medicines for these viral infections remains lacking. Berberine (BBR) is an alkaloid found in some plants used in traditional medicines in Southeast Asia and elsewhere, and BBR has been shown to possess anti-viral activities. During a screen for potential application to mosquito transmitted viruses, BBR was shown to have virucidal activity against dengue virus (DENV; IC50 42.87 µM) as well as against Zika virus (IC50 11.42 µM) and chikungunya virus (IC50 14.21 µM). BBR was shown to have cellular effects that lead to an increase in cellular DENV E protein without a concomitant effect on DENV nonstructural proteins, suggesting an effect on viral particle formation or egress. While BBR was shown to have an effect of ERK1/2 activation this did not result in defects in viral egress mechanisms. The primary effect of BBR on viral production was likely to be through BBR acting through AMPK activation and disruption of lipid metabolism. Combined these results suggest that BBR has a dual effect on DENV infection, and BBR may have the potential for development as an anti-DENV antiviral.

Oroxylin A shows limited antiviral activity towards dengue virus

“…Assessment of virucidal activity was undertaken as previously described [ 5 , 7 , 14 ] and was performed by direct incubation of stock DENV 2 with OA (10, 50 or 100 µM) or DMSO (0.01, 0.05, 0.1%) or DMEM for 1 h at 37 °C. Viral titer was then determined by plaque assay as described elsewhere [ 13 ].…”

“…The treatment conditions were essentially previously described [ 7 ]. Briefly BHK-21 cells were treated with selected concentrations of OA (or vehicle control) in three different treatment conditions.…”

“…In pre-treatment, cells were treated with OA for 2 h prior to DENV 2 (MOI 2) or mock infection and after 2 h incubation cells were washed with PBS and then maintained in complete media under standard conditions for 24 h. In post-treatment, cells were infected with DENV 2 or mock infected for 2 h before washing with PBS and adding complete media containing OA or vehicle control before incubation under standard conditions for 24 h. In the combined pre- and post-infection treatment, cells were both pre-incubated and post infection incubated with compound or vehicle control, but the infection was undertaken in the absence of the compound or vehicle control. At 24 h post-infection, cell pellets were collected for flow cytometry analysis of viral infectivity as previously described [ 7 ], and the supernatants of the same conditions were also collected for standard plaque assays to determine infectious viral titer.…”

“…Flow cytometry was undertaken as previously described [ 7 ]. Briefly, cells were collected by trypsinization followed by centrifugation, blocked with 10% goat serum (Thermo Fisher Scientific, Waltham, MA) before fixing with 4% paraformaldehyde (Merck KGaA, Darmstadt, Germany) and subsequently permeabilizing with 0.2% Triton X-100.…”

“…Thailand, as with many countries in Asia has a long history of natural medicine usage, with a number of plants being identified as having antipyretic properties. Based on the identification of compounds from plants that have antipyretic use in Thai medicine we have previously shown that the flavonoid kaempferol, a constituent of Moringa oleifera and Coccinia grandis amongst a number of other sources, berberine a bioactive constituent of Tinospora crispa and Berberis vulgaris and andrographolide from Andrographis paniculata possess anti-flaviviral activities [ 5 – 7 ]. As part of our ongoing work in identifying antiviral agents from Thai natural medicines we screened oroxylin A (OA), an O-methylated flavone that is found in several parts of Oroxylum indicum [ 8 ].…”