Possible therapeutic effects of Nigella sativa and its thymoquinone on COVID-19.

CONTEXT: COVID-19 is a novel coronavirus that causes a severe infection in the respiratory system. Nigella sativa L. (Ranunculaceae) is an annual flowering plant used traditionally as a natural food supplement and multipurpose medicinal agent. OBJECTIVE: The possible beneficial effects of N. sativa, and its constituent, thymoquinone (TQ) on COVID-19 were reviewed. METHODS: The key words including, COVID-19, N. sativa, thymoquinone, antiviral effects, anti-inflammatory and immunomodulatory effects in different databases such as Web of Science (ISI), PubMed, Scopus, and Google Scholar were searched from 1990 up to February 2021. RESULTS: The current literature review showed that N. sativa and TQ reduced the level of pro-inflammatory mediators including, IL-2, IL-4, IL-6, and IL-12, while enhancing IFN-γ. Nigella sativa and TQ increased the serum levels of IgG1 and IgG2a, and improved pulmonary function tests in restrictive respiratory disorders. DISCUSSION AND CONCLUSIONS: These preliminary data of molecular docking, animal, and clinical studies propose N. sativa and TQ might have beneficial effects on the treatment or control of COVID-19 due to antiviral, anti-inflammatory and immunomodulatory properties as well as bronchodilatory effects. The efficacy of N. sativa and TQ on infected patients with COVID-19 in randomize clinical trials will be suggested.