ABSTRACT
Nigella sativa L. has been used in folk medicine for treatment of many diseases. The oil and seed constituents, in particular thymoquinone (TQ), have shown promising medicinal properties in the treatment and prevention of various diseases. The present study aims to investigate the potential effect of TQ on airway-induced hypersensitivity. Ovalbumin (OVA) sensitization and challenge in guinea pig tracheal muscle preparation were used in order to investigate the anti-asthmatic activity of TQ. To study the effect of TQ on acute lung injury, lipopolysaccharide (LPS) induced lung injury method was used. In addition, rat peritoneal mast cells (RPMCs) were collected to investigate the histamine release from the mast cells. Furthermore, to study the anti-allergic activity of TQ, the systemic anaphylactic shock technique induced by compound 48/80 was performed. Pretreatment with TQ (3 mg/kg, i.p.) for 5 days prior to ovalbumin sensitization showed a marked decrease in the response of the tracheal spirals to acetylcholine and histamine, as spasmogens in a cumulative dose response–curve. TQ (8mg/kg, i.p.) prevented most of the pathological detrimental changes that occurred in response to the endotoxin LPS as the inflammatory cells infiltration, lipid peroxidation (LP), glutathione depletion (GSH), tumor necrosis factor-alpha (TNF- α) and interlukin-1 beta (IL-1β) levels in both boronchoalevolar lavage fluid (BALF) and lung tissue homogenates. Sensitization of rats induced a significant increase in the histamine release from RPMCs which is inhibited by pretreatment with TQ (8 mg/kg, i.p.). Similarly, pretreatment of mice with TQ (50 and 100 mg/kg), 1hr prior to injection of compound 48/80 (8mg/kg, i.p.) significantly inhibited the % of mortality of mice following the systemic anaphylactic reaction. Considering the anti-asthmatic, anti-inflammatory, antioxidant and anti-allergic activities of TQ reported in this study, one can conclude that TQ could be of therapeutic potentials in treating various diseases associated with airway-induced hypersensitivity.