Expectorant, antitussive, anti-inflammatory activities and compositional analysis of Aster tataricus

The root of Aster tataricus L. f., recorded in all versions of Chinese Pharmacopoeia, is a traditional Chinese medicine with the function of dispelling phlegm and relieving cough for more than 2000 years. This study was designed to evaluate the expectorant, antitussive, and anti-inflammatory activities of the root of A. tataricus and to explore the chemical substances responsible for these activities.

The 70% ethanol extract of the root of A. tataricus (RA-70) was divided into three fractions, Fr-0, Fr-50 and Fr-95. They were all orally administrated to the mice to investigate their potential expectorant activities by a tracheal phenol red secretion method. The most effective fraction, together with shionone, was evaluated the expectorant, antitussive and anti-inflammatory activities by the mouse models of phenol red secretion, ammonia-induced cough, and xylene-induced ear swelling. Furthermore, the chemical components of the effective fraction were analyzed and identified by an HPLC-Q-TOF/MS method.

Treatment with RA-70, Fr-0 and Fr-50 increased the amount of phenol red secretion by 65.3%, 56.5%, and 76.9%, respectively. Fr-50 was chosen for the further investigation and the results showed that Fr-50 at 40, 80 mg/kg significantly enhanced the phenol red secretion of tracheas, increased the latent period and decreased the frequency of cough and inhibited the ear edema in mice. Shionone at 80 mg/kg showed the trend of enhancing sputum secreting, but had no effect on ammonia-induced cough and xylene-induced ear edema. HPLC-Q-TOF/MS analysis indicated that Fr-50 was mainly composed of 12 caffeoylquinic acids (40.8%, in relative peak area), 7 astersaponins (12.0%) and 13 astins/asterinins (pentapeptides, 26.5%).

The root of A. tataricus has significant expectorant, antitussive and anti-inflammatory effects. Caffeoylquinic acids, astersaponins, and aster peptides, rather than shionone, may be the main constituents responsible for the expectorant and antitussive activities of A. tataricus and act in a synergistic way.