In Vitro Assessment of a Natural Monoterpene as an Antiviral Compound against Low Pathogenic Human Coronavirus 229E

The emergence of novel viruses, including SARS-CoV-2, has highlighted the need for effective antiviral treatments. This study aimed to evaluate the antiviral potential of pine oil and α-terpineol against low pathogenic coronavirus 229E (HCoV-229E), which serves as an alternative model for COVID-19. The study investigated the virucidal, adsorption, and multiplication inhibitory effects of pine oil and α-terpineol on HCoV-229E, as well as their impact on proinflammatory gene expression in an infected human colorectal adenocarcinoma cell line. Pine oil and α-terpineol exhibited high CC50 values and moderate in vitro inhibitory activity against HCoV-229E, with selectivity indices of 8.23 and 7.7, respectively. Plaque reduction tests demonstrated that these compounds effectively suppressed HCoV-229E during the adsorption and replication stages, and they were found to reduce the expression of proinflammatory genes associated with the development of a cytokine storm. The findings of this study suggest that pine oil and α-terpineol possess significant antiviral properties against HCoV-229E and warrant further investigation as potential therapeutic agents for viral infections, including COVID-19.