Testing Essential Oils' Ability to Kill Common Cold Viruses

Jenn Hoskins
8th May, 2024

Testing Essential Oils' Ability to Kill Common Cold Viruses

The study found that among four essential oils tested for their ability to kill a norovirus surrogate, only lemon balm (Melissa officinalis) demonstrated significant virucidal activity.

Photo adapted from: Daniel Cahen / CC BY (Source)

Key Findings

  • In a University of Bari Aldo Moro study, only lemon balm essential oil reduced a norovirus surrogate's viral load
  • Thyme, rosemary, and sage essential oils did not significantly lower the virus levels under tested conditions
  • Lemon balm oil achieved more than a 50% reduction in infectious virus particles after 10 minutes of exposure
Norovirus (NoV) is a notorious culprit behind many cases of acute gastroenteritis (AGE), an intestinal infection marked by symptoms like diarrhea, vomiting, and stomach pain. It's a significant health concern globally and is especially problematic in settings like hospitals and nursing homes, where it can cause severe outbreaks[2]. Despite its prevalence, studying NoV has been challenging due to difficulties in cultivating the human strains of the virus in laboratory conditions. This has led researchers to use surrogate viruses, such as feline calicivirus (FCV) and murine NoV, to test the effectiveness of potential antiviral agents[1]. Essential oils (EOs) are concentrated plant extracts that have been recognized for their antimicrobial properties. Given the need for effective antivirals against NoV and the potential of EOs, the University of Bari Aldo Moro conducted a study to evaluate the virucidal efficacy of four specific EOs against FCV, a stand-in for human NoV. The oils tested included Melissa officinalis L. (lemon balm), Thymus vulgaris L. (thyme), Rosmarinus officinalis L. (rosemary), and Salvia officinalis L. (sage). The study aimed to determine whether these EOs could significantly reduce the viral load of FCV. Viral load refers to the number of virus particles present in a given volume, an important measure of the virus's ability to cause infection. The researchers exposed the virus to various concentrations of each EO for different lengths of time, ranging from 10 minutes to 8 hours, to assess the speed and extent of the virucidal action. The results revealed that, with the exception of Melissa officinalis L. EO (MEO), none of the EOs at any concentration or contact time led to a significant decrease in FCV viral titers. This finding suggests that thyme, rosemary, and sage EOs may not be effective against FCV under the conditions tested. However, MEO showed promise; at a high concentration, it was capable of reducing the FCV viral load by 0.75 log10 Tissue Culture Infectious Dose (TCID50)/50 μl after just 10 minutes of contact. To clarify, TCID50 is a measure of infectious virus particles, and a 0.75 log10 reduction indicates that the number of infectious units was reduced by more than half. This study is significant because it provides insights into natural compounds that could potentially be used to combat NoV, which, as earlier studies have shown, is a leading cause of viral AGE in the U.S. and other parts of the world[3]. The high incidence of norovirus, particularly among children and the elderly, underscores the need for effective preventive measures and treatments[3]. Although the surrogate virus FCV was used in this study, the findings could have implications for the development of antiviral strategies against human NoV, provided that the observed effects translate to the human strains of the virus. The research also builds on prior knowledge about the transmission and management of norovirus outbreaks[2]. Given that norovirus can spread through contaminated food, and considering the optimization of methods for detecting NoV in food[4], the potential use of EOs as a disinfectant or a food additive to reduce viral contamination deserves further investigation. In summary, the University of Bari Aldo Moro's research contributes to the ongoing search for effective antiviral agents against norovirus. While three of the tested EOs did not exhibit significant virucidal activity against FCV, lemon balm EO showed potential. These findings could pave the way for more in-depth studies on the use of MEO against NoV and its possible applications in preventing or managing norovirus outbreaks, especially in vulnerable populations.

MedicineBiochemPlant Science

References

Main Study

1) Assessing the virucidal activity of essential oils against feline calicivirus, a non-enveloped virus used as surrogate of norovirus.

Published 15th May, 2024 (future Journal edition)

https://doi.org/10.1016/j.heliyon.2024.e30492

Related Studies

2) Norovirus gastroenteritis.

Journal: Current infectious disease reports, Issue: Vol 9, Issue 2, Mar 2007

3) Incidence of Norovirus and Other Viral Pathogens That Cause Acute Gastroenteritis (AGE) among Kaiser Permanente Member Populations in the United States, 2012-2013.

https://doi.org/10.1371/journal.pone.0148395

4) Optimization of methods for detecting norovirus on various fruit.

https://doi.org/10.1016/j.jviromet.2008.07.022


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