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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. [ABSTRACT FROM AUTHOR]

This study evaluated the synergistic antifungal effects of vapor-phase natural agents against Aspergillus flavus with an aim to prevent fungal contamination in agricultural products. Screening different combinations of natural antifungal vapor agents using the checkerboard assay revealed that the cinnamaldehyde and nonanal (S CAN) blend could exert the strongest synergistic antifungal activities against A. flavus , with a minimum inhibitory concentration (MIC) of 0.03 μL/mL, which caused a 76 % decrease in fungal population compared to when each agent was used separately. Subsequent gas chromatography–mass spectrometry (GC/MS) analysis demonstrated that the cinnamaldehyde/nonanal combination was stable and no effects on their individual molecular structures. S CAN at 2 × MIC completely inhibited the fungal conidia production and mycelial growth. The calcofluor white (CFW) and dichloro-dihydro-fluorescein diacetate (DCFH-DA) staining assays showed that S CAN treatment could accelerate the destruction of cell wall integrity and accumulation of reactive oxygen species (ROS) in A. flavus. Moreover, pathogenicity assay indicated that in contrast to separate treatment with cinnamaldehyde or nonanal, S CAN could cause a decrease in the production of A. flavus asexual spores and AFB1 on peanuts, which verified its potential synergistic activity against fungal propagation. In addition, S CAN effectively preserves the organoleptic and nutritional properties of stored peanuts. Overall, our findings strongly indicated that the cinnamaldehyde/nonanal combination is a potentially significant antifungal agent against A. flavus contamination during the postharvest storage of peanuts. • Combined Cinnamaldehyde and nonanal (S CAN)vapors exert the strongest synergistic antifungal activities against A. flavus • The mechanism of S CAN against A. flavus is related to cell wall integrity destruction and ROS accumulation. • S CAN could reduce the pathogenicity of A. flavus infection, and preserve the sensory and nutritional properties of peanut. [ABSTRACT FROM AUTHOR]