Herbal polysaccharides and cough reflex.

In the last decades plant substances have become a leading form of treatment of many respiratory symptoms, including cough. It has been shown that compounds purified form polysaccharides from Adhatoda vasica, Withania somnifera, and Glycyrrhiza glabra have various biological activities, such as antioxidant, anti-inflammatory, immunomodulating, antispasmodic action, or antiallergic properties, and they often act as cough suppressants. This work demonstrates new natural substitutes for synthetic antitussives whose application is associated with numerous adverse effects. We investigated pharmacodynamic characteristics of arabinogalacatan samples extracted from A. vasica, W. somnifera, and G. glabra. These extracts showed the ability to reduce citric acid-induced cough in awake guinea pigs after oral administration in a dose of 50mg/kg. The strongest antitussive effect (81%) was found after application of the extract from G. glabra. There was a 67% cough suppression with A. vasica and 61% with W. somnifera, which was comparable with the antitussive activity of codeine (62%).