The role of thymoquinone, a major constituent of Nigella sativa, in the treatment of inflammatory and infectious diseases

Nigella sativa (N. sativa) is an annual flowering plant that has been used as a traditional remedy for many centuries. The seed possesses a large variety of compounds with thymoquinone (TQ) considered its major but not sole bioactive constituent. Supercritical fluid extraction, geographical location, and oxidative status of N. sativa produces the highest yield of essential oil content including TQ. Thymoquinone is lipophilic, heat and light sensitive with low oral bioavailability and rapid elimination that have significantly inhibited its pharmacological development. Novel developments in nanoparticulate-based oral administration, nasal spray and transdermal delivery may allow the clinical development of N. sativa and TQ as therapeutic agents. Animal and human studies indicate a potential role of N. sativa seed oil and TQ for a diverse range of disease processes including hypertension, dyslipidaemia, type 2 diabetes mellitus, arthritis, asthma, bacterial and viral infections, neurological and dermatological disorders, as it belongs to the group of pan-assay interference compounds. This review outlines the pharmacological properties of N. sativa and TQ and their potential wide application for a large variety of human diseases. The paper will focus on recent studies of the anti-inflammatory and antiviral properties that make N. sativa and TQ promising therapeutic agents targeting contemporary inflammatory and infectious diseases including Covid 19.