Potential therapeutic effects of Nigella sativa and its constituents,
thymoquinone on COVID-19 based on immunomodulatory effects
Abstract
The novel coronavirus (COVID-19) is a kind of viral pneumonia and
emerging pathogen that causes a severe respiratory infection in humans.
The research on COVID-19 is still in the primary stage and international
attention has raised to develop treatment option. The main death cause
of COVID-19 is acute respiratory distress syndrome (ARDS). The main
mechanisms for ARDS is the cytokine storm that release the large amounts
of pro-inflammatory cytokines. The other corona virus such as, severe
acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cause to reduction
of CD4+ and CD8+ T cells in the peripheral blood of infected patients.
Some medicinal plants produce essential oils that are used in
traditional and modern medicine, and in the food, cosmetics, and
pharmaceutical industry. We aimed to summarize the possible therapeutic
effects of Nigella sativa and its constituents, thymoquinone based on
immunomodulatory effects on COVID-19. The databases including; Web of
Science (ISI), PubMed, Scopus and google scholar were used to search for
keywords such as, COVID-19, Nigella sativa, thymoquinone, Antivirus, and
Immunomodulatory effects. N. sativa extract and thymoquinone (TQ)
reduced the level of cytokines including; IL-2, IL-4, IL-6, and IL-12,
while enhanced IFN-γ in the bronchoalveolar lavage fluid and serum. They
also increased the serum levels of IgG1 and IgG2a. N. sativa and TQ
decreased T helper 2 (Th2)/Th1 and Th2/ Regulatory T cells (Tregs)
ratios due to elevation of IL-10 but suppression of IL-4. Then this
medicinal plant and its constituents might be beneficial effects in
control and treatment of COVID-19.