Effects of Nigella sativa and its constituents on total white blood cells count and airway responsiveness value in ovalbumin-induced asthma models: A preclinical systematic review and meta-analysis.

Objective: Evidence indicates that Nigella sativa (NS) and its key compounds such as carvacrol, thymoquinone, thymol, and α-hederin exhibit properties that reduce inflammation, act as antioxidants, and modulate the immune system. This meta-analysis investigated the preclinical evidence of NS reported in animal models of ovalbumin (OVA)-induced asthma. Materials and Methods: Studies done on NS and its components in animal models of OVA-induced asthma in all published articles up to July 2024 were searched in Scopus, PubMed, and Web of Science databases. The studies underwent assessment of methodological quality utilizing the 15-point CAMARADES checklist. MedCalc software was utilized for performing the data analysis. Results: Sixteen studies involving a total of 486 animals, with 243 in the intervention group and 243 in the ovalbumin-induced group were analyzed. In the meta-analysis results, it was shown that NS and its components notably decreased total white blood cells (WBC), eosinophils, lymphocytes, and neutrophils. Additionally, NS caused a shift in the half of the maximum effective concentration (EC50) curve to the right and decreased the maximum response rates and tracheal OVA-response in experimental animals. Conclusion: NS, and its components, could potentially influence asthma induced by OVA in animals by improving airway responsiveness and exhibiting anti-inflammatory and anti-oxidant properties. Consequently, it is recommended that NS be evaluated in additional clinical trials for patients with asthma.