Ultrastructural Damages to H1N1 Influenza Virus Caused by Vapor Essential Oils

Abstract

Influenza viruses are transmitted from human to human via airborne droplets and can be transferred through contaminated environmental surfaces. Some works have demonstrated the efficacy of essential oils (EOs) as antimicrobial and antiviral agents, but most of them examined the liquid phases, which are generally toxic for oral applications. In our study, we describe the antiviral activity of Citrus bergamia, Melaleuca alternifolia, Illicium verum and Eucalyptus globulus vapor EOs against influenza virus type A. In the vapor phase, C. bergamia and M. alternifolia strongly reduced viral cytopathic effect without exerting any cytotoxicity. The E. globulus vapor EO reduced viral infection by 78% with no cytotoxicity, while I. verum was not effective. Furthermore, we characterized the EOs and their vapor phase by the head-space gas chromatography–mass spectrometry technique, observing that the major component found in each liquid EO is the same one of the corresponding vapor phases, with the exception of M. alternifolia. To deepen the mechanism of action, the morphological integrity of virus particles was checked by negative staining transmission electron microscopy, showing that they interfere with the lipid bilayer of the viral envelope, leading to the decomposition of membranes. We speculated that the most abundant components of the vapor EOs might directly interfere with influenza virus envelope structures or mask viral structures important for early steps of viral infection.

Thyme essential oil inhibits intracellular replication of CyHV‐3 and inactivates extracellular virus. An in vitro study

“…Electron microscopy revealed that thymol disrupted the envelope of HSV‐1 (Lai et al, 2012). Furthermore, an envelope of H1N1 influenza virus was partially decomposed after exposure to vapours of bergamot essential oil and destroyed after exposure to tea tree essential oil (Madia et al, 2022). It is, therefore, very likely that the destruction of the CyHV‐3 envelope might be the mechanism for virucidal activity of TEO.…”

Essential Oils from Mediterranean Plants Inhibit In Vitro Monocyte Adhesion to Endothelial Cells from Umbilical Cords of Females with Gestational Diabetes Mellitus

“…Much evidence from in vitro and animal studies proves that EOs have multiple biological activities, such as anticancer [ 4 , 5 ], antiviral [ 6 , 7 , 8 , 9 ], antibacterial [ 10 , 11 , 12 , 13 ], antifungal [ 14 , 15 ], antibiofilm [ 16 , 17 , 18 ], anti-inflammatory [ 19 , 20 , 21 ], and antioxidant [ 19 , 22 , 23 , 24 , 25 ] effects, which constitute the starting point for the in vivo assessment of those properties in various therapeutic and cosmetic fields [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. Nevertheless, since great consideration has been given to the effective use of EOs in clinical procedures, further systematic animal studies and clinical investigations are needed.…”