Protective Effect of 1,8-Cineole (Eucalyptol) on Respiratory System: A Systematic Review and Meta-analysis from Animal Studies

Background 1,8-Cineole is used in traditional folk medicine to treat various diseases. This study evaluates the protective effects of 1,8-cineole on the respiratory system by investigating its impact on inflammatory factors in animal studies. Materials and Methods We conducted searches in PubMed, Medline, Embase, Cochrane, and the Web of Science databases until December 2023. This study utilized Get Data Graph Digitizer 2.26, EndNote, and RevMan 5.4. The random effects model and standard mean difference (SMD) were applied for data analysis. Results The results showed tumor necrosis factor-alpha (TNF-α) (SMD: −8.19, 95% CI: −11.30 to −5.08, p < 0.00001), interleukin (IL)-6 (SMD: −7.38, 95% CI: −10.61 to −4.15, p < 0.00001), IL-1β (SMD: −19.18, 95% CI: −32.57 to −5.79, p = 0.005), NF-κB (SMD: −6.26, 95% CI: −7.88 to −4.65, p < 0.00001), neutrophils (SMD: −8.16, 95% CI: −11.65 to −4.67, p < 0.00001), and macrophages (SMD: −5.06, 95% CI: −8.06 to −2.05, p = 0.001). Conclusion The study suggests that 1,8-cineole significantly inhibits the expression of inflammatory factors, indicating its potential for further study and development.