Platycodin D and D3 increase airway mucin release in vivo and in vitro in rats and hamsters.

The root of Platycodon grandiflorum has been widely used for the treatment of various chronic inflammatory diseases including airway disease in oriental medicine. The root extract of the plant has been known to be effective in the expectoration of sputum or mucus, thereby improving airway respiratory function and preventing secondary airway inflammation. In this study, we investigated the effect of platycodin D and D3, the saponin components that are anti-inflammatory components in Platycodon grandiflorum. Platycodin D and D3 increased mucin release from rat and hamster tracheal surface epithelial cell culture and also from intact rat trachea upon nebulization. The effect of platycodin D3 was stronger than that of ATP, a potent mucin secretagogue and also of ambroxole, a mucolytic drug. The results from the present study suggest that platycodin D and D3 are useful as expectorant agents in the treatment of various airway diseases.