effects of viola tricolor flower hydroethanolic extract on lung inflammation in a mouse model of chronic asthma

Asthma is a chronic inflammatory disease of the lungs driven by t cell activation. viola tricolor l. as a traditional medical herb could suppress activated t lymphocytes and has been used empirically for asthma remedy. in the present study, we investigated the anti-inflammatory effect of viola tricolor and its underlying mechanism on asthma characteristics induced by ovalbumin (ova) in mice. balb/c mice were randomly divided into six groups: normal control, ovalbumin (ova) control, ova mice treated with viola tricolor (50, 100 and 200 mg/kg) and dexamethasone (3 mg/kg). all mice except normal controls were sensitized and challenged with ova. asthmatic mice were treated orally in the last 7 days of ova challenge. the total and differential leukocyte counts, interleukin (il)-4 and interferon (ifn)-γ levels in bronchoalveolar lavage fluid (balf) were determined. h&e staining for lung inflammation was performed. viola tricolor treatment at 200 mg/kg significantly decreased il-4 level but did not considerably affect the ifn-γ level. therefore, it effectively reduced asthma characteristics including infiltration of leukocytes particularly eosinophil and peribronchial inflammation as compared to dexamethasone. however, viola tricolor at 100 mg/kg had the most prominent inhibitory effect on the il-4 level and also markedly increased ifn-γ level. as result, it prevented further reduction of inflammatory parameters in this group compared to the viola tricolor-treated group at 200 mg/kg. our study demonstrated that viola tricolor has anti-inflammatory effects via inhibition of t-helper type 2 (th2) cytokine production and validated its empirical usage in traditional medicine.