Cough and Arabinogalactan Polysaccharide from the Bark of Terminalia Arjuna

In this work we investigated the antitussive activity of the medicinal tree Terminalia arjuna. We used the stem bark for extraction and preparation of water extracted isolate and its two fractions: acetone-soluble (TA-S) and acetone precipitated (TA-P) fraction. The presence of a pectic arabinogalactan was confirmed in TA-P fraction by chromatographic and spectroscopic analysis. The antitussive activity of samples was assessed after oral administration in a dose of 50 mg.kg(-1) in healthy guinea pigs, in which cough was elicited by inhalation of citric acid (0.3 mol/L) in body plethysmograph. The water extracted isolate showed a significant ability to decrease the number of cough efforts by 64.2 %; the antitussive activity on par with that of codeine phosphate. The TA-P fraction showed the antitussive activity of 54.8 %. In contrast, TA-S fraction had only a mild antitussive activity. No changes in in vivo airway resistance were noted. We conclude that arabinogalactan is an essential component of Terminalia arjuna that underlies its antitussive action.