Abstract
The authors previously found that codeine was rather ineffective against coughing and aggravation of coughing due to angiotensin-converting enzyme inhibitors in the presence of airway inflammation and that Bakumondo-to had a marked antitussive effect. In this study, the effects of Bakumondo-to and ophiopogonin isolated/extracted from Bakumondo (ophiopogonin tubes) on airway inflammatory mediators, in particular tachykinin and its cleavage enzyme neutral endopeptidase (NEP), were investigated.
In animals with bronchitis, airway NEP activity decreased to 1/8-1/9 of that in healthy animals, and Bakumondo-to prevented the reduction in NEP activity. Bakumondo-to and ophiopogonin also suppressed tachykinin-and phosphoramidon (an NEP inhibitor) -induced coughing while codeine was almost ineffective.
These results clarified part of the physiology of airway clearance as well as the pathophysiology and the mechanism of repair which have not been well understood. The results suggest that Chinese medicines and their crude drug constituents are useful resources for the development of the next generation of pharmaceuticals contributing to the radical cure of diseases.
