LAUSR

This work explored the compositions of a crude extract of peels of Citrus x aurantium using a gas chromatography-mass spectrometry (GC-MS) technique. The crude extract of peels of C. × aurantium was analyzed by GC-MS revealing the presence of limonene as the major compound, accounting for 93.7% of the total. Virucidal activity of the oil of C. x aurantium peels against influenza A virus H1N1 was evaluated by the ASTM E1053-20 method. Moreover, the virucidal activity was also investigated of D-limonene, the major terpene in essential oils of C. x aurantium, and its enantiomer L-limonene. The essential oil of the C. x aurantium peels produced a log reduction of 1.9 to 2.0, accounting for 99% reduction of the virus, while D- and L-limonene exhibited virucidal activity with a log reduction of 3.70 to 4.32 at concentrations of 125 and 250.0 µg/mL, thus reducing the virus by 99.99%. Previous work found that D-limonene exhibited antiviral activity against herpes simplex virus, but L-limonene, an enantiomer of D-limonene, has never been reported for antiviral activity. This work demonstrates the antiviral activity of L-limonene for the first time. Moreover, this work suggests that concentrations of 0.0125% to 0.025% of either D- or L-limonene can possibly be used as a disinfectant against viruses, probably in the form of essential oil sprays, which may be useful disinfectants against the airborne transmission of viruses, such as influenza and COVID-19.