Antibacterial, Immunomodulatory, and Lung Protective Effects of Boswellia dalzielii Oleoresin Ethanol Extract in Pulmonary Diseases: In Vitro and In Vivo Studies

Lung diseases such as asthma, chronic obstructive pulmonary diseases, and pneumonia are causing many global health problems. The COVID-19 pandemic has directed the scientific community’s attention toward performing more research to explore novel therapeutic drugs for pulmonary diseases. Herein, gas chromatography coupled with mass spectrometry tentatively identified 44 compounds in frankincense ethanol extract (FEE). We investigated the antibacterial and antibiofilm effects of FEE against Pseudomonas aeruginosa bacteria, isolated from patients with respiratory infections. In addition, its in vitro immunomodulatory activity was explored by the detection of the gene expression of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), nitric oxide synthase (iNOS), cycloxygenase-2 (COX-2), and nuclear factor kappa-B (NF-κB) in lipopolysaccharide (LPS)-induced peripheral blood mononuclear cells (PBMC). In addition, its anticancer activity against the A549 lung cancer cell line and human skin fibroblast (HSF) normal cell line was studied. Moreover, the in vivo lung protective potential of FEE was explored histologically and immunohistochemically in mice using a benzo(a)pyrene induced lung damage model. FEE exhibited antibacterial and antibiofilm activities besides the significant inhibition of gene expression of TNFα, IL-6, and NF-κB. FEE also exerted a cytotoxic effect against A549 cell line. Histological and immunohistochemical investigations with morphometric analysis of the mean area percentage and color intensity of positive TNF-α, COX-2, and NF-κB and Bcl-2 reactions revealed the lung protective activity of FEE. This study outlined the promising therapeutic activity of oleoresin obtained from B. dalzielii in the treatment of different pulmonary diseases.