Study on Spectrum-Effect Relationship of Rhizoma Rhei, Cortex Magnoliae Officinalis, Fructus Aurantii Immaturus and their Formula

Rhizoma Rhei, Cortex Magnoliae Officinalis and Fructus Aurantii Immaturus compose DaChengQi Tang (DCQT), a classical formula of traditional Chinese medicine (TCM) that is used for acute intestinal obstruction and has been proven to be effective and economic. However, the ingredients of TCM are complicated, and it is unclear which ingredients are the most important for its effects. In this paper, the relationship between the spectra and effects is discussed to provide a powerful method and some insights into the quality control of the herbs and their formula. High-performance liquid chromatographic (HPLC) fingerprint analysis was performed to investigate the chemical structures in different batches of Rhizoma Rhei, Cortex Magnoliae Officinalis, Fructus Aurantii Immaturus and DCQT. Hierarchical clustering analysis was employed to evaluate the similarities between fingerprints. Animal model of small intestinal propulsion was established to study the purgative functions of the herbs and DCQT. The relationship between the chemical ingredients and the effects was explored by regression analysis. HPLC fingerprint analysis results demonstrated variations between ingredients in different batches of Rhizoma Rhei, Cortex Magnoliae Officinalis, Fructus Aurantii Immaturus and DCQT. The origin, collection time and preparation process may have contributed to these differences. Small intestinal propulsion results showed that, compared with the control group, the positive and therapeutic groups including single herbs and formula were significantly effective (P < 0.05). Spectrum-effect relationship results indicated that seven peak ingredients, hesperidin, aloe-emodin, honokiol, rhein, magnolol, emodin and sennoside A, were inducted in the regression equation, among which, the influence of sennoside A was the largest and most positively associated with the effects. The data analysis results indicated that many ingredients contributed to the purgative effects, among which, sennoside A might be the most important effective component; therefore, sennoside A should be determined for quality control. Furthermore, the spectrum-effect relationship is simple, operative and suitable for the quality evaluation of TCM.