Efficacy Confirmation Test of Immature Asian Pear (Pyrus pyrifolia Nakai) Extract on Ovalbumin-Induced Asthma in Mice

Abstract

Allergic asthma is a chronic inflammatory disease characterized by the infiltration of leukocytes, particularly eosinophils, into the airways, resulting in respiratory dysfunction. To develop new asthma treatment materials with minimal side effects and excellent bioactivities, we evaluated the efficacy of immature Asian pear extract (IAP extract; 400–100 mg/kg) in alleviating ovalbumin (OVA)-induced asthma in female C57BL/6J mice. This study assesses various parameters associated with OVA-induced allergic asthma including lung weight, macroscopic necropsy findings, the total cell count in bronchoalveolar lavage fluid (BALF), the total leukocyte count and leukocyte differential count, serum ovalbumin-specific Ig E (OVA-sIg E) levels, interleukin (IL)-4 and IL-5 contents in BALF, histopathological changes in the lungs, and alterations in oxidative stress and inflammation-related mRNA expressions. The results of this study demonstrate clear asthma-related findings in the OVA control group. However, the oral administration of IAP extract (at doses ranging from 400 to 100 mg/kg) significantly suppressed the anti-inflammatory and antioxidant activities by regulating the expressions of phosphoinositide 3-kinase/protein kinase B/phosphatase and TENsin homolog deleted on chromosome 10 (PI3K/Akt/PTEN), p38 mitogen-activated protein kinase (p38 MAPK), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in a dose-dependent manner. These effects are comparable to those observed with dexamethasone at a concentration of 0.75 mg/kg. As a result, the oral administration of an appropriate dose of IAP extract holds promise as a potential natural drug or health-functional food material for improving respiratory function.