In vitro comparison of three common essential oils mosquito repellents as inhibitors of the Ross River virus

Abstract

BackgroundThe essential oils of Cymbopogon citratus (CC), Pelargonium graveolens (PG) and Vetiveria zizanioides (VZ) are commonly used topically to prevent mosquito bites and thus the risk of infection by their vectored pathogens such as arboviruses. However, since mosquito bites are not fully prevented, the effect of these products on the level of viral infection remains unknown.ObjectivesTo evaluate in vitro the essentials oils from Reunion Island against one archetypal arbovirus, the Ross River virus (RRV), and investigate the viral cycle step that was impaired by these oils.MethodsThe essential oils were extracted by hydrodistillation and analyzed by a combination of GC-FID and GC×GC-TOF MS techniques. In vitro studies were performed on HEK293T cells to determine their cytotoxicity, their cytoprotective and virucidal capacities on RRV-T48 strain, and the level of their inhibitory effect on the viral replication and residual infectivity prior, during or following viral adsorption using the reporter virus RRV-renLuc.ResultsEach essential oil was characterized by an accurate quantification of their terpenoid content. PG yielded the least-toxic extract (CC50 > 1000 μg.mL-1). For the RRV-T48 strain, the monoterpene-rich CC and PG essential oils reduced the cytopathic effect but did not display virucidal activity. The time-of-addition assay using the gene reporter RRV-renLuc showed that the CC and PG essential oils significantly reduced viral replication and infectivity when applied prior, during and early after viral adsorption. Overall, no significant effect was observed for the low monoterpene-containing VZ essential oil.ConclusionThe inhibitory profiles of the three essential oils suggest the high value of the monoterpene-rich essential oils from CC and PG against RRV infection. Combined with their repellent activity, the antiviral activity of the essential oils of CC and PG may provide a new option to control arboviral infection.

Antiviral Effects of Plant-Derived Essential Oils and Their Components: An Updated Review

“…Also, EOs may target genome related sites as revealed by genetic approaches [31]. Towards a certain type of virus, mechanisms of action may be EO dependent [32], possibly owing to the constitutional variations of the EOs. Summing up, the direct interaction of EOs with free viruses tends to be the most common mode of action.…”

“…Ralambondrainy et al [32] reported that monoterpene-rich Cymbopogon citratus and Pelargonium graveolens EOs exhibited higher antiviral effect on the Ross River Virus, while the sesquiterpene-rich Vetiveria zizanioides EO showed an insignificant effect. However, it seems arbitrary for the author to draw an inference that the antiviral competency was ascribed to the monoterpenes without further experimental proofs.…”

Doratoxylon apetalum, an Indigenous Medicinal Plant from Mascarene Islands, Is a Potent Inhibitor of Zika and Dengue Virus Infection in Human Cells

“…To further characterize the antiviral mechanism and the stage of ZIKV infection affected by D. apetalum extract, we examined the impact of the plant extract on various stages of the dissected virus replication cycle (pre-entry, entry and post-entry). In addition, wash steps were included to ensure the specificity of the treatment on the distinct stage examined [22,33]. In order to study pre-entry—more specifically, the ability of D. apetalum to induce host cell innate immunity prior virus addition [34]—A549 cells were pretreated with D. apetalum (200 µg·mL −1 ) for 6h (Figure 4A: pre-treatment).…”

Essential Oils as Repellents against Arthropods

“…Peppermint and lavender were effective as potential repellents in cotton with inclusion complexes of β -cyclodextrin [ 68 ]. Currently, eco-friendly and cost-effective EOs with antiviral capacity against arboviruses such as Ross River virus (RRV) are being studied [ 69 ]. Three EOs from Cymbopogon citratus (CC), Pelargonium graveolens (PG), and Vetiveria zizanioides (VZ) with repellent activities were evaluated for antiviral effects, in terms of prevention of viral entry, using a wild-type RRV-T48 strain, and viral replication, using a recombinant RRV expressing Ren luciferase.…”