RESUMEN
Chimonanthus nitens Oliv. leaf (CNOL), as a traditional Chinese medicine, has been widely used for the treatment of influenza and colds over a long history. However, the mechanism of colds related to the effects of CNOL have been little studied. In this study, the anticomplement and antitussive activities of different polarity extracts of CNOL were evaluated. Ethyl acetate extract (EAE) among different extracts not only significantly decreased cough times by 21-58% (P < 0.01), but also had anticomplement effects demonstrated by the CH50 values of 0.100 mg/ml. A total of 28 constituents (10 coumarins, 13 flavonoids and five phenolics) were identified in EAE based on the ultra-high-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry technique. Eight compounds in EAE were evaluated by an ammonia-induced cough model to reveal the antitussive mechanisms and classical anticomplement pathway. The results indicated that the antitussive effects of scopoletin, kaempferol-3-O-rutinoside and kaempferol may depend on central mechanisms and that flavonoids such as compounds of kaempferol-3-O-rutinoside and kaempferol have better anticomplementary activity than coumarins like compounds of scopolin, scopoletin and isofraxidin. Taken together, kaempferol-3-O-rutinoside and kaempferol could be important chemical markers in the present study that might be used to evaluate the quality and biological activity of CNOL.