Ethanol extracts of Saururus chinensis suppress ovalbumin-sensitization airway inflammation

Aim of the study: The aerial part of Saururus chinensis has been used in folk medicine to treat several inflammatory diseases in China and Korea. Previously, our group reported that anti-asthmatic activity of an ethanol extract of Saururus chinensis (ESC) might occur, in part, via the inhibition of prostaglandin D2 (PGD2) and leukotriene C4 (LTC4) production, and degranulation reaction in vitro, as well as through the down-regulation of interleukin (IL)-4 and eotaxin mRNA expression in an in vivo ovalbumin-sensitization animal model. However, the effects of Saururus chinensis on eicosanoid generation, as well as Th2 cytokines and eotaxin production in an in vivo asthma model, have not been fully investigated. Moreover, it has not been determined whether ESC can ameliorate airway inflammation in vivo. In the present study, we investigated the therapeutic activity of Saururus chinensis on ovalbumin (OVA)-sensitized airway inflammation and its major phytochemical compositions. Materials and methods: Asthma was induced in BALB/c mice by ovalbumin-sensitization and inhalation. ESC (10–100mg/kg) or dexamethasone (5mg/kg), a positive control, was administered 7 times orally every 12h from one day before the first challenge to 1h before the second challenge. The recruitment of inflammatory cells and hyperplasia of goblet cells were evaluated by H&E and PAS staining. Levels of Th2 cytokines, eotaxin, PGD2 and LTC4 were measured to evaluate the anti-inflammatory activity of ESC in OVA-sensitized mice. Contents of major components were analyzed by HPLC using a reversed-phase C18 column. Results: ESC (10mg/kg) suppressed allergic airway inflammation by inhibition of the production of IL-4 (P <0.001), IL-5 (P <0.05), IL-13 (P <0.001), eotaxin (P <0.001), PGE2 (P <0.001), LTC4 (P <0.001) in lung extract and IgE level (P <0.001) in the serum. In addition, ESC (50mg/kg) reduced the infiltration of inflammatory cells and hyperplasia of goblet cells in the lung tissues. The anti-inflammatory effect of ESC was comparable to that of the positive control drug, dexamethasone. Its major phytochemical composition includes manassantin A, B and sauchinone. Conclusions: These results suggest that ESC decreased inflammation and mucus secretion in the OVA-induced bronchial asthma model, and its anti-asthmatic activity may occur in part via the inhibition of Th2 cytokines and eotaxin protein expression, as well as through prostaglandin E2 (PGE2) and leukotriene C4 (LTC4) generation. This effects may be attributed particularly to the presence of manassantin A, B and sauchinone major component evidenced by a HPLC analysis. [Copyright &y& Elsevier]