Renata Baranauskienė

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

Background The 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. Objectives To 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. Methods The 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. Results Each 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. Conclusion The 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.

Essential oils (EOs), pressurized liquid extracts (PLE) and carbon dioxide supercritical fluid extracts (SFE-CO 2 ) from Algerian Thymus munbyanus as valuable sources of antioxidants to be used on an industrial level

The aim of this study was to demonstrate the potential of extracts from Algerian Thymus munbyanus as a valuable source of antioxidants for use on an industrial level. To this end, a study was conducted on the composition and antioxidant activities of essential oils (EOs), pressurized liquid extracts (PLE) and supercritical fluid extracts (SFE-CO2) obtained from Thymus munbyanus subsp. coloratus (TMC) and subsp. munbyanus (TMM). EOs and SFE-CO2 extracts were analysed by GC-FID and GC×GC-TOFMS revealing significant differences. A successive extraction of the solid SFE-CO2 residue by PLE extraction with solvents of increasing polarity such as acetone, ethanol and water, was carried out. The extracts were evaluated for total phenolic content by Folin-Ciocalteu assay, while the antioxidant power was assessed by DPPH, FRAP, and ORAC assays. SFE-CO2 extracts were also analysed for their tocopherol content. The antioxidant activity of PLE extracts was found to be higher than that of SFE-CO2 extracts, and this increased with solvent polarity (water > ethanol > acetone). Overall, these results support the use of T. munbyanus as a valuable source of substances to be used on an industrial level as preservative agents.

Supercritical CO2 extracts and essential oils from Teucrium polium L. growing in Algeria: chemical composition and antioxidant activity

ABSTRACT In this work, we studied the essential oils (EOs) obtained by hydrodistillation and lipophilic fractions extrated by carbon dioxide supercritical fluid extraction (SFE-CO2) from Teucrium polium (Lamiaceae). EOs and SFE-CO2 extracts were analyzed by GC and GC-TOFMS. EOs showed qualitative differences compared with SFE-CO2 extracts, though in both products germacrene D was the most abundant component. Notably a new EO chemotype, characterzed by germacrene D, β-eudesmol, shyobunol, and δ-cadinene, was reported. EOs along with SFE-CO2 extracts, plant powder, and solid residue after SFE were evaluated for total phenolic content (TPC) and antioxdiant activity by DPPH, FRAP, and ORAC assays. The raw plant material was the most active, followed by the solid residue after SFE-CO2 extraction. On the other hand, EO and SFE-CO2 extracts displayed weak activity. These results showed that the antioxidant compounds of T. polium are of hydrophilic nature and are not extracted or retained in the plant material after SFE-CO2 extraction.