Inhibitory effects of Picrasma quassioides (D.Don) Benn. on airway inflammation in a murine model of allergic asthma.

Picrasma quassioides (D.Don) Benn. (PQ) is used in traditional medicine for the treatment of inflammatory conditions, including gastritis. This study aimed to evaluate the inhibitory effects of PQ on the inflammatory responses in mice with allergic asthma induced by ovalbumin (OVA) and in lipopolysaccharide (LPS)‑stimulated RAW264.7 cells. To induce allergic asthma, the mice underwent OVA sensitization on days 0 and 14 and then were challenged with OVA from days 21‑23. The mice were administered 15 and 30 mg/kg doses of PQ 1 h prior to the OVA challenge. The PQ treatment decreased the inflammatory cell count in the bronchoalveolar lavage fluid of the mice and reduced the levels of interleukin (IL)‑4, IL‑5, IL‑13 and immunoglobulin (Ig)E when compared with those in the OVA group. The PQ treatment also reduced the airway hyperresponsiveness induced by the OVA challenge, attenuated the recruitment of inflammatory cells and the mucus production in the airways of the mice. In the LPS‑stimulated RAW264.7 cells, the PQ treatment reduced the overexpression of inducible nitric oxide synthase (iNOS). The results indicated that PQ inhibits inflammatory responses in mice with OVA‑sensitized/challenged allergic asthma and in LPS‑stimulated RAW264.7 cells. These effects were considered to be associated with the suppression of iNOS expression. Therefore, PQ may have the potential to treat airway inflammatory diseases, including allergic asthma.