NMR based metabolomic comparison of the antitussive and expectorant effect of Farfarae Flos collected at different stages.

Farfarae Flos (FF) is widely used for the treatment of cough, bronchitis, and asthmatic disorders in the Traditional Chinese Medicine (TCM). According to the experience of TCM, only the flower bud can be used as herbal drug, and its medicinal quality becomes lower after blooming. However, the underlying scientific basis for this phenomenon is not fully understood. In this study, the chemical components and the bioactivities of the FF collected at three different development stages were compared systematically. NMR based fingerprint coupled with multivariate analysis showed that the flower buds differed greatly from the fully opened flower both on the secondary and primary metabolites, and the animal experiments showed that the fully opened flower exhibited no antitussive or expectorant effect. In addition, the endogenous metabolites correlated with the antitussive and expectorant effect of FF were also identified. These findings are useful for understanding the rationality of the traditional use of FF, and also suggested the components responsible for the antitussive and expectorant effect of FF.