Synergistic Antiviral Effects of Combined Fractions from Eucalyptus camaldulensis Against SARS-CoV-2

GabAllah, Mohamed; Shaker, Kamel; Abulhamd, Ashraf T.; El-Shesheny, Rabeh

doi:10.21608/ejchem.2025.367126.11429

Synergistic Antiviral Effects of Combined Fractions from Eucalyptus camaldulensis Against SARS-CoV-2

Articles in Press

Document Type : Original Article

Authors

¹ Center of Scientific Excellence for Influenza Viruses, Water Pollution Research Department, Environment and Climate Change Research Institute, National Research Centre, Giza, Egypt.

² Botany and Microbiology Department, Faculty of Science (Boys), Al Azhar University, Cairo, Egypt.

³ Chemistry of Natural Compounds Department, Pharmaceutical and Drug Industries Research Institute, National Research Centre, Giza, Egypt.

10.21608/ejchem.2025.367126.11429

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused substantial global issues that significantly impacted public health. The emergence of SARS-CoV-2 variants poses a great challenge for pandemic control efforts, including developing vaccines and antiviral therapeutics. Natural remedies derived from various aromatic and medicinal plants have been used for centuries in traditional medicine systems for their potential antiviral properties. Here, we examined the in vitro antiviral activity of Eucalyptus camaldulensis extract and its different fractions of leaves and bark against SARS-CoV-2. The cytotoxicity concentration (CC50) for these fractions ranged between ~ 105.7 and 586 µg/mL. Methanol extract of eucalyptus and its fractions were shown to inhibit SARS-CoV-2 at half-maximal inhibitory concentrations (IC50) of ~ 3 to 134 µg/mL. The inhibitory effect of the dichloromethane fraction from the leaves and bark of the eucalyptus plant was moderate for each, reaching 61.1% and 56.3%, respectively. However, after combining both fractions, the inhibition percentage reached 73.7% using the highest safe concentration, indicating that the inhibitory effect changed from moderate to promising due to the synergy between the components of the monoterpenes and sesquiterpenes compounds. The major phytochemical constituents were analyzed using GC-MS analysis. The bark fraction showed the presence of monoterpenes and sesquiterpenes as major components, while the leaves showed sesquiterpenes only. GC-MS of the highly antiviral dichloromethane fraction for the combined leaves and bark revealed the presence of spathulenol and pinanediol as main components. These findings indicate that Eucalyptus camaldulensis compounds are potentially useful as highly effective antiviral agents against SARS-CoV-2, and further preclinical studies are recommended.

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