Evaluation of the possible potential of essential oils present in emulsion or under vapour against Covid-19

已知精油(Eos)及其化学成分对多种病毒具有活性，如1型单纯疱疹病毒(HSV 1)(Astani等人，2010年)。精油中的活性化合物通常与萜类的存在有关，特别是单萜和酚类化合物，它们是精油中的挥发性成分。一些关于天然提取物和精油的报道表明，在乳胶相和气相中都有一定程度的抗冠状病毒活性(Mani等人，2020年)。由于新的冠状病毒株新冠肺炎仍未完全被了解，目前还不可能找到哪种Eos将提供最好的保护水平。然而，可以合理地假设，一些Eos和相关的萜烯可能提供可测量的防御水平，就像它们对其他已知病毒如HSV 1所做的一样。我们在几项研究中证明，在蒸汽或溶液中的Eos可以抑制细菌和真菌，甚至可以抑制病毒，即诺沃克病毒(柑橘提取物中的黄酮类化合物)(Gobeil等人，2020年)。该建议的主要目的是：(1)用肉汤微量稀释法和棋盘法评估乳化状态下Eos对新冠肺炎的最低抑菌浓度和分数抑制浓度(FIC计算：评价Eos之间的协同作用)；(2)使用一种新的肉汤挥发棋盘法评估蒸气状态Eos对新冠肺炎的MIC和FIC值；(3)开发可用于溶液或蒸气状态下新冠肺炎的Eos配方。这项研究的结果将有助于开发乳液形式的抗新冠肺炎配方或用于各种用途的蒸汽应用，如工作或食品表面，甚至用于空气净化。

The essential oils (EOs) and their chemical constituents are known to be active against a wide range of viruses like herpes simplex virus type 1 (HSV 1) (Astani et al., 2010). The active compounds in essential oils are normally related to the presence of terpenes, especially monoterpenes and phenolic compounds which are the volatiles part in essential oils. Some reports on natural extracts and essential oils have demonstrated antiviral activity against coronaviruses to some extent in both emulsion phase and vapor phase (Mani et al., 2020). Since the new strain of coronavirus, Covid-19, is still not completely understood, it is not yet possible to find which EOs will offer the best level of protection. However, it is plausible to assume that some of the EOs and related terpenes are likely to offer a measurable level of defense in the same way that they do with other known viruses such as HSV 1. We have demonstrated in several studies that EOs in vapor or in solution can inhibit bacteria and fungus, and even virus i.e. norovirus (flavonoids from citrus extract) (Gobeil et al., 2020). The main objectives of the proposal are: (1) Evaluate the minimum inhibitory concentrations (MIC) and fractional inhibitory concentrations (checkerboard method) of EOs (FIC calculation: evaluation of the synergy between EOs) under emulsion form against Covid-19 using broth microdilution and checkerboard method; (2) Evaluate the MIC and FIC of EOs in vapor form against Covid-19 using a new broth volatilization checkerboard method; (3) Develop EOs formulation that could be applied under solution or vapor form on Covid-19. The results of the study will permit to develop anti Covid-19 formulations under the form of emulsion or for vapor application for diverse applications such as working or food surface or even for air decontamination.