Antitussive Activity of Extracts from Fallopia Sachalinensis

Giant knotweed (Fallopia sachalinensis) and related plants are commonly used in Chinese and Japanese folk medicine. Bioactive natural products derived from them are believed to possess a variety of biologic activities. We have analyzed two polysaccharide fractions from leaves of Fallopia sachalinensis. We have focused on its activities to experimentally induced cough reflex and the changes of specific airway resistance. We have compared the observed antitussive activity with cough suppressing activity of codeine ("positive" control) and effect acquired after application of water for injection ("negative" control) using conscious male guinea pigs individually placed in a double chambers bodyplethysmograph box. Peroral administration of both polysaccharides significantly inhibited the number of coughs induced by citric acid in guinea pigs and have not significantly changed the values of specific airway resistance. Moreover, the substances in experimental animals have not provoked any notable adverse events. The biological activity observed in derivatives of Fallopia sachalinensis provides a scientific basis for the use of the plant in traditional medicines.