Extracted polysaccharide from Nyctanthes arbor-tristis leaves: chemical and antitussive properties.

The prevalence of cough is reflected in antitussives being one of the most widely used therapies in the world; however no new class of drugs has been introduced into the market for many years. Water decoction of the leaves of Nyctanthes arbor-tristis L. is used in Indian Ayurvedic system to alleviate a wide range of diseases including cough. Herein, we have isolated a carbohydrate polymer (CP) containing fraction from its leaves by aqueous extraction method. CP is a branched polysaccharide containing, amongst others, 1,3-/1,3,6-linked galactopyranosyl, 1,5-/1,3,5-linked arabinofuranosyl and 1,2-/1,2,4-linked rhamnopyranosyl residues. Oral administration of CP fraction in doses of 25 and 50 mg kg(-1) body weight significantly inhibited the number of citric acid-induced cough efforts in guinea pigs in a dose dependent manner. Remarkably, CP did not altered specific airway resistance of animals significantly. Consequently, aqueous extraction method provided a molecular entity, which exhibited the cough suppressive activity: this could symbolize an attractive approach in phytotherapeutic treatment.