In vitro Potential Antiviral SARS-CoV-2 activity of Thymoquinone, the main Nigella sativa component

COVID-19 pandemic has been an unprecedented challenge to global public health, intensifying the need for effective antiviral treatments against SARS-CoV-2 and its variants. Among the myriad of compounds explored, thymoquinone (TQ), a natural constituent of Nigella sativa (black seed), has garnered interest for its potential therapeutic properties. This study aims to investigate the antiviral efficacy of thymoquinone against the Omicron variant of SARS-CoV-2 through comprehensive in vitro experiments. The research utilizes two distinct protocols to assess thymoquinone’s capacity to inhibit viral replication at different stages, both as a prophylactic agent and as a post-infection treatment. Various concentrations of TQ were tested, and dose/response curves were generated to assess the half-maximal effective concentration (EC50) in both protocols. Additionally, MTT assay was used to assess the cytotoxicity due to each TQ concentration. The results demonstrate a significant inhibition of viral replication, with comparable efficacy observed between the preventive and therapeutic applications of TQ. The obtained EC50 (46,19 µM and 54,161 µM respectively for preventive and treatment approaches) suggest that TQ has a broad spectrum of action, and when comparing both EC50 to the CC50 (65,68 µM), it is evident that TQ has a favorable therapeutic index, making it a potential safe and versatile candidate for both preventive and therapeutic purposes against SARS-CoV-2