Abstract
Allergic asthma is a complex disorder characterized by chronic airway inflammation. Patients with asthma often show poor adherence to corticosteroid therapy owing to prominent side effects, which provides a rationale to explore new drug classes with a better safety profile. In this study, we sought to discover natural products that inhibit the activity of phosphodiesterase 4, which is considered a potential molecular target for anti-inflammatory therapy. The screening of a plant extract library led to the identification of Distylium racemosum, which inhibited phosphodiesterase 4 activity in vitro and suppressed lipopolysaccharide-induced inflammatory signaling in cultured cells. In a mouse model of ovalbumin-induced allergic asthma, D. racemosum treatment significantly reduced inflammatory responses in the lung, as well as serum immunoglobulin E levels. Although the active constituents of D. racemosum extract and the exact mechanism underlying the in vivo action of D. racemosum remain to be elucidated, our results provide a basis for further investigation of D. racemosum extract as a novel anti-inflammatory agent for allergic asthma.
Key words
Distylium racemosum
- Hamamelidaceae - allergic asthma - phosphodiesterase 4 - inflammation
