Quality evaluation of Pterocephali Herba through simultaneously quantifying 18 bioactive components by UPLC-TQ-MS/MS analysis

Pterocephali Herba (PH), the dried whole plant of Pterocephalus hookeri, is a Tibetan medicine commonly used to treat rheumatoid arthritis (RA). Iridoids, triterpenoids, flavonoids and phenylpropanoids are the major groups of bioactive constituents from PH. However, only ursolic acid and oleanolic acid, two unspecific triterpenoid components, are used as markers for the quality control of PH in Chinese Pharmacopoeia. Herein, an UPLC-TQ-MS/MS integrating SIR and MRM mode method for simultaneously quantifying 18 components, i.e., 9 iridoids, 3 triterpenoids, 3 phenylpropanoids, 2 flavonoids and quinic acid, in PH was developed and validated, and was used to evaluate 10 batches of PH samples from different origins. Hierarchical cluster analysis (HCA) was used to show the clustering of PH samples, while spearman correlation analysis was adopted to evaluate the correlation between ursolic acid/oleanolic acid and other quantified components. It was found that the established method was sensitive, precise, and accurate enough for the simultaneous quantification of 18 analytes in PH samples. Significant differences were found among the contents of 18 components in PH samples, no apparent clustering of the quality of PH samples was found to be related to its origins, and the contents of ursolic acid/oleanolic acid were only significantly correlated to the content of sylvestroside I, dipsanoside B, dipsanoside A in PH. Our results suggested that the newly established multi-components quantitative method is an improved approach for quality evaluation of PH samples. Furthermore, the holistic quality was inconsistent among PH samples, and ursolic acid/oleanolic acid alone could not indicate the holistic quality variation trend of PH.