Structural features and antitussive activity of water extracted polysaccharide from Adhatoda vasica

Antitussive drugs are amongst the most widely used medications worldwide; however no new class of drugs has been introduced into the market for many years. Natural compounds offer interesting pharmacological perspectives for antitussive drug development. In this study, we have analyzed a pectic arabinogalactan isolated from Adhatoda vasica by aqueous extraction and precipitation with ethanol. This polysaccharide is branched and consisted mainly of 1,3-/1,3,6-linked galactopyranosyl and 1,5-/1,3,5-linked arabinofuranosyl residues. Peroral administration of this arabinogalactan (50 mg kg−1 body weight) inhibited the number of coughs induced by citric acid in guinea pigs and slightly decreased the values of specific airway resistance.