Japanese Loquat (Eriobotrya Japonica) Seed Extract, a Rich Source of Beta-Sitosterol Inhibits Airway Hyperresponsiveness in BALB/C Mice

Seed extract of Loquat fruit (Eriobotrya japonica) is abundant in anti-oxidant components, such as beta sitosterol, which may have beneficial effects on asthmatic inflammation. We investigated preventative effects of diluted loquat seed extract (DLSE) on mouse asthmatic airway inflammation. BALB/c mice sensitized by exposure to Dermatophagoides farinae (Der f) with diesel exhaust particles (DEPs) were given DLSE ad libitum. Serum Der f -specific IgG1 titers and cytokine profiles in bronchoalveolar lavage fluids (BALF) were analyzed. We found that DLSE suppressed Der f-specific IgG1 serum levels and airway hyperresponsiveness (AHR) in allergen-induced mice. DLSE-treated mice had significantly decreased secretions of IL-5, IL-13, TGFβ1 and MCP-1 and up-regulated IFN-γ secretion. The number of inflammatory cells in BALF was considerably reduced in DLSE-treated Der f + DEP induced (DD) group as compared with asthmatic group (Tap water/ Der f + DEP (TD)). Regarding inflammatory cells in BALF, a significant reduction of eosinophils was observed in DD group as compared with TD group (p<0.05). In TD group, the intensity of airway resistance increased simultaneously with the increase in acetylcholine concentration in a dose-dependent way. AHR was significantly inhibited in DD groups as compared with the TD group (p<0.05). Regarding serum specific-IgG1, significantly lower levels of this antibody were observed in DD groups as compared with the TD group (p<0.05). DLSE treatment attenuated Th2 cytokines production and AHR in Der f + DEP -induced asthmatic mice. Our results strongly suggest that DLSE may have significant therapeutic benefits for the control of allergic airway disorders.