Study on the application of intestinal absorption in vitro coupled with bioactivity assessment in Yuanhu Zhitong preparation

Abstract

Generally, crude herbal extracts contain hundreds of components, and only the absorbed constituents among them may produce possible pharmacological effects. In previous studies, researchers directly utilized crude herbal extracts into cells or organs culture system for pharmacological test, which might easily result in false positive or false negative results. Therefore, reasonable pharmacological methods for investigation of crude herbal drugs in vitro were greatly needed. The objective of this research is to study the feasibility of combination of two simple biological methods, intestinal absorption test and vasorelaxation assay in the pharmacological research of Yuanhu Zhitong preparation (YZP). The intestinal absorption test was carried out to investigate the accounts of seventeen constituents in YZP and prepare the intestinal absorbed samples for vasorelaxation assay. The 17 absorbed constituents in three concentrations of YZP (0.16, 0.08, 0.04 g/ml) were detected by rapid resolution liquid chromatography coupled with a triple quadruple electrospray tandem mass spectrometry. The vasorelaxation of absorbed YZP solutions were determined by isolated aorta test and a mixture containing 7 main detected constituents was chosen for bioassay. The accounts of 17 constituents in YZP significantly varied. The good vasorelaxation of YZP was first found on the endothelium-intact aorta precontracted by KCl (60 mmol/L), with the relaxation rate of 81.53 ± 3.98, 66.85 ± 10.01 and 43.64 ± 17.83% at three different concentrations (0.16, 0.08 and 0.04 g/ml). However, the bioassay results of the mixture showed that it had lower bioactivity than that of the preparation. Based on adequate biopharmaceutical properties, the combinative methods may be more reasonable than conventional method in pharmacological research, and the intestinal absorption test coupled with vasorelaxation evaluation can be used together to investigate vasoactive effects of Traditional Chinese Medicine (TCM) in vitro. Key words: Intestinal absorption, vasorelaxation, Yuanhu Zhitong preparation, aortic rings, Traditional Chinese medicine.