Study on the bioactive components of Banxia Xiexin Decoction with different decocting methods and its effects on ulcerative colitis rats from the perspective of phase states

Banxia Xiexin Decoction (BXD) is one of the seven classic prescriptions of the special decoction method (SDM) of "removing dregs and decocting again", which has been widely used in inflammatory bowel diseases such as ulcerative colitis (UC). However, the impacts of SDM have not been fully investigated, either on the components or on the biological effects. This study aimed to investigate the rational of SDM traditionally recorded about BXD, re-decoction after dreg-removal, by comparing with the contemporary general decoction method (GDM) from the perspective of phase states, in the bioactive components from the perspective of phase states, and their corresponding pharmacodynamic effects on a particular UC rat model. The BXD decoctions were respectively obtained by SDM and GDM, together with the different samples with different decocting time. The phase state samples (true solution, colloidal phase, and precipitated phase), were also obtained after a series of separation process and characterized. The multi-components in the in-process decoctions, original decoctions and phase state samples were quantitatively determined. HPLC fingerprint spectrum of the samples were also detected and compared with chemometrics analysis. A rat model of ulcerative colitis with cold-heat complex syndrome was established, on which the pharmacodynamic effects of different phases of SDM-made BXD were investigated. The results showed that the contents of eight marker components in SDM-made decoction were significantly higher than those in GDM-made decoction. Compared with the precipitated phases and true solutions, the colloidal phase was confirmed to obtain absolutely higher contents of the components (except berberine). The analysis on HPLC fingerprints also revealed that the profiles of colloidal phase showed the majority of the characteristics of original decoctions, when compared with the other phases. The results showed the BXD group, precipitated phase group and colloidal phase group had certain therapeutic effects on the ulcerative colitis rats with cold-heat complex syndrome, among which the original decoction group showed optimal effects, followed by the colloidal phase. The study has provided the experimental evidence of the bioactive components and pharmacodynamic effects on the rational of SDM, as originally recorded about the classic prescription, which might provide useful idea for the interpretation on medicinal properties of TCM compound prescriptions, and contemporary TCM innovative drug developments.