Virucidal activity of Colombian Lippia essential oils on dengue virus replication in vitro

The inhibitory effect of Lippia alba and Lippia citriodora essential oils on dengue virus serotypes replication in vitro was investigated. The cytotoxicity (CC50) was evaluated by the MTT assay and the mode of viral inhibitory effect was investigated with a plaque reduction assay. The virus was treated with the essential oil for 2 h at 37ºC before cell adsorption and experiments were conducted to evaluate inhibition of untreated-virus replication in the presence of oil. Antiviral activity was defined as the concentration of essential oil that caused 50% reduction of the virus plaque number (IC50). L. alba oil resulted in less cytotoxicity than L. citriodora oil (CC50: 139.5 vs. 57.6 μg/mL). Virus plaque reduction for all four dengue serotypes was observed by treatment of the virus before adsorption on cell. The IC50 values for L. alba oil were between 0.4-32.6 μg/mL and between 1.9-33.7 μg/mL for L. citriodora oil. No viral inhibitory effect was observed by addition of the essential oil after virus adsorption. The inhibitory effect of the essential oil seems to cause direct virus inactivation before adsorption on host cell.

Antiviral activity of the green marine alga Ulva fasciata on the replication of human metapneumovirus

We evaluated the antiviral activity of the marine alga, Ulva fasciata, collected from Rasa beach and Forno beach, Búzios, Rio de Janeiro, Brazil on the replication of human metapneumovirus (HMPV). The algae extracts were prepared using three different methodologies to compare the activity of different groups of chemical composites obtained through these different methodologies. Four out of the six extracts inhibited nearly 100% of viral replication. The results demonstrated that the majority of the extracts (five out of six) possess virucidal activity and therefore have the ability to interact with the extracellular viral particles and prevent the infection. On the other hand, only two extracts (from Forno beach, obtained by maceration and maceration of the decoction) were able to interact with cell receptors, hindering the viral entry. Finally, only the extract of algae collected at Forno beach, obtained by maceration presented intracellular activity. To our knowledge, this is a pioneer study on antiviral activity of marine algae against HMPV. It is also the first on antiviral activity against HMPV ever done in Brazil. The study also shows the effect of different environment factors and different chemical procedures used to obtain the extract on its biological properties.

Anti-HSV-1 and anti-HIV-1 activity of gallic acid and pentyl gallate

The synthetic n-alkyl esters of gallic acid (GA), also known as gallates, especially propyl, octyl and dodecyl gallates, are widely employed as antioxidants by food and pharmaceutical industries. The inhibitory effects of GA and 15 gallates on Herpes Simplex Virus type 1 (HSV-1) and Human Immunodeficiency Virus (HIV-1) replication were investigated here. After a preliminary screening of these compounds, GA and pentyl gallate (PG) seemed to be the most active compounds against HSV-1 replication and their mode of action was characterized through a set of assays, which attempted to localize the step of the viral multiplication cycle where impairment occurred. The detected anti-HSV-1 activity was mediated by the inhibition of virus attachment to and penetration into cells, and by virucidal properties. Furthermore, an anti-HIV-1 activity was also found, to different degrees. In summary, our results suggest that both compounds could be regarded as promising candidates for the development of topical anti-HSV-1 agents, and further studies concerning the anti-HIV-1 activity of this group of molecules are merited.