4. Conclusions
A HPLC-UV chromatographic fingerprint analysis of P. nodiflora was established. The antioxidant assay and the chromatogram profile of this plant could provide information about the main significant secondary metabolites represented by onopordin (4) and eupafolin (7). The results indicated that the contents of active constituents varied greatly among the PNM samples collected in different periods, with the total contents of active constituents being higher in PNM collected in the summer. This could be helpful for further evaluation of the quality of PNM.