Effects of the root of Platycodon grandiflorum on airway mucin hypersecretion in vivo and platycodin D(3) and deapi-platycodin on production and secretion of airway mucin in vitro.

We investigated whether aqueous extract of the root of Platycodon grandiflorum A. de Candolle (APG), platycodinD(3) and deapi-platycodin significantly affect the production and secretion of airway mucin using in vivo and in vitro experimental models. Effect of APG was checked on hypersecretion of pulmonary mucin in sulfur dioxide-induced bronchitis in rats. Confluent NCI-H292 cells were pretreated with platycodinD(3) or deapi-platycodin for 30min and then stimulated with PMA (phorbol 12-myristate 13-acetate) for 24h. The MUC5AC mucin production and secretion were measured by ELISA. The results were as follows: (1) APG stimulated the secretion of airway mucin in sulfur dioxide-induced bronchitis rat model; (2) platycodinD(3) and deapi-platycodin inhibited the production of MUC5AC mucin induced by PMA from NCI-H292 cells, respectively; (3) however, platycodinD(3) and deapi-platycodin did not inhibit but stimulated the secretion of MUC5AC mucin induced by PMA from NCI-H292 cells, respectively. This result suggests that aqueous extract of P. grandiflorum A. de Candolle and the two natural products derived from it, platycodinD(3) and deapi-platycodin, can regulate the production and secretion of airway mucin and, at least in part, explains the traditional use of aqueous extract of P. grandiflorum A. de Candolle as expectorants in diverse inflammatory pulmonary diseases.